TECH AND TUNING TIPS

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These tips are a compilation of facts from VHP and Crane Cams Engineers.
We sincerely hope you can benefit from this information.

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Tech Tips

Why Crane Cams Measures “Advertised Duration” at .004” Lifter Rise
From Mark Campbell
V.P. Market & Product Development...Crane Cams

 We are frequently asked why Crane Cams measures the “Advertised Duration” of hydraulic lifter camshafts at .004” lifter rise (on the cam lobe) when several competitors measure their advertised duration at .006” lifter rise.  The answer is that we attempt to comply with the SAE (Society of Automotive Engineers) J604 standard.  This standard states that automotive camshafts should have their duration measured at .006” lift at the valve.  On pushrod engines, lift at the valve is the product of (“cam lobe lift” x “rocker arm ratio”).  Most popular pushrod engines use rocker ratios of 1.5, 1.6 or 1.7.  When you divide .006” lift at the valve by any of the popular ratios, you come up with .004” when the answer is rounded to three decimal places.  Using .006” lift at the lobe results in at least .009”lift at the valve.  That is quite a difference from the SAE standard of .006” lift at the valve.

This difference in measurement of advertised duration does make the “intensity” of Crane Cams lobes appear to be “less aggressive” when compared to the competition.   “Camshaft Lobe Intensity” is frequently defined as the difference between the “advertised duration” and the “duration @ .050” lifter rise”.  It is generally accepted that the lower the number of degrees of difference between these two figures relates to the greater the amount of “Camshaft Lobe Intensity” (or aggressiveness in the lobe design).  “Camshaft Lobe Intensity” is only valid, however, when the advertised duration of two camshafts is measured at the same point. At first glance, it would not appear the .002” of lifter rise measurement would make much difference in the perceived “Lobe Intensity”.  The fact, however, is this is the first part of the lift curve where any clearance in the valve train is “taken up”; and the lift rate at this initial point is at its slowest point.  Consequently, .002” lifter rise difference can create a significant misrepresentation of actual “Camshaft Intensity”.  When comparing lobe profiles, it is best to compare cam lobes at exactly the same points. 

 Keep in mind that the discussion above is about hydraulic lifter camshafts in pushrod engines.  For overhead cam engines (OHC) where there is no rocker ratio, Crane Cams measures duration at .006” valve lift.  That creates different issues when comparing duration (and related power ranges) of camshafts used in pushrod engines as compared with OHC engines.  See Crane Cams Enginebuilder Newsletter #31 dated February 22, 2007 @ www.cranecams.com. 

So who is right and who is wrong here?  At Crane Cams, we are only claiming to comply with the SAE J604 standard.  That way, Crane Cams can be evaluated with other cams that comply with the accepted world standard.

Vinci Hi-Performance subscribes to this same practice and supports Crane Cams efforts to comply with  SAE standards. We think everyone should comply with these standards to keep the playing field fair and properly inform our clients.
  

How To Compare Duration Specs Between Pushrod Cams and OHC!

 Years ago, the method of comparing cams by their duration at .050” of lifter rise was developed.  This has become an industry standard, and the term “duration at fifty” implies the duration of the camshaft lobe between .050” of lifter rise on the opening ramp and .050” distance of the lifter from returning to the base circle on the closing ramp.  Engine builders familiar with various cams have come to recognize that a cam that is 204 degrees at .050” is a mild street cam, and one that is 244 at .050” is a serious street/bracket race cam.  This same description has a distorted meaning, however, when used to describe overhead cams.

 Overhead cams may not have conventional lifters that ride on the lobes.  They either work directly on the valve through a mating component (bucket follower) or operate through a follower that acts much like a rocker arm.  With OHC engines, “duration at .050” means duration of the lobe measured at the time that the valve is open .050”.  This is distinctly different than duration at .050” with the pushrod.  Consider a small-block Chevy with the lifter at .050” rise on the lobe.  The 1.5:1 rocker ratio would cause the valve to be at .075” lift.  Working backwards, .050” lift of the valve would only be .033” of lifter rise.  Comparing the duration of the same lobe measured at .033” lifter rise and at .050” lifter rise will result in a larger duration number with the .033” lifter rise measurement than with the .050” lifter rise measuring point.  Since OHC durations are figured at the valve (not a lifter rise point), we must subtract approximately 15 degrees of duration from the OHC duration at .050” figures to get a comparable “pushrod” duration at .050” figure pushrod.  That is why some of our mild street cams for OHC engines seem so big.  An OHC with a “duration at .050” of 220 degrees has the performance characteristics of a pushrod cam with approximately 205 degrees at .050”.

 Keep in mind that this is an approximation for comparison. OHC cams are much more complex in design than traditional pushrod cams.  This is especially true of cams with finger followers because the effective rocker ratio is constantly changing as the cam rotates through its opening and closing cycle.  Different diameters of bucket followers also have an effect on cam design and performance. For this an other reasons a cam that works well in a Mod Ford, for instance, will not work well in an LSX engine. Also, reverse duration specs can create havoc when used in the wrong application. We have these types of grinds available for very specialized applications.

 

 

·         Rocker Arm Geometry  -  If you’re looking for the most out of your valvetrain, you’ll need to look at your rocker arm geometry (Stud Mount Rockers).  To fine tune your valvetrain, you are looking for a pushrod length that leaves the roller tip of the rocker towards the intake side of the valve tip, NOT dead center of the valve, when the valve is closed.  You will see that the pushrod side of the rocker probably will have to drop down, and the roller tip will then pull back toward the intake side.  This will be achieved with shorter length pushrods and will help you get better power because you will be opening the valve quicker.  This will also leave the highest spring pressure load occurring with the rocker tip at the center of the valve at full lift, not off towards the exhaust side.  Just be careful not to get into contact with the top of the retainer and the underside of the rocker arms when setting up this geometry.

 

    Lofting  is a term used to explain a lifter leaving the surface of the cam lobe and thrown over the nose of the cam.  This will happen at higher engine speeds after the valve train is accelerated up the opening side of the lobe and in a period of rebound.  The rebound period occurs on the opening side of the lobe when the lifter is still on the rise portion of the lift curve and extends beyond the nose of the cam.  When the inertia load becomes greater than the open load provided by the valve spring, separation will occur over the nose and extend down the closing side of the lobe.  If a smooth and controlled connection to the closing side of the lobe no longer occurs due to increasing engine speed, the potential for valve train damage dramatically increases.  Lofting can be minimized by the use of rigid, low mass valve train components, such as hollow stem valves, titanium components, and short large diameter pushrods. Limiting engine speed during wheel spin and missed shifts will also minimize the chance of valve train damage.

 

Ignition Timing vs. Valve Timing

Frequently, our phone techs get inquiries from our customers about what ignition timing to run with a given camshaft.  Sometimes, they ask about how ignition timing relates to valve timing (cam timing).  The answers to these questions are difficult because there is really no way to answer their questions with the limited amount of information provided. 

First of all, ignition timing is the timing of the spark plug firing with respect to piston position in the cylinder.  Valve timing is the point expressed in degrees of crankshaft position at which the intake valve opens (IO) and closes (IC) and when the exhaust valve opens (EO) and closes (EC).  Ignition timing has nothing to do with valve timing and everything to do with cylinder pressure, flame speed in the combustion chamber, air/fuel ratio and piston position.  Valve timing is totally independent of these factors.  While the ignition distributor is driven by the camshaft (or the ECU determines piston position based on a camshaft/crankshaft position sensor), ignition timing is independent of when the valves open or close. 

Admittedly, camshafts with significant overlap (and low idle vacuum) usually require more initial timing at idle.  However, total timing at WOT or part throttle cruise is independent of valve timing.  If more timing is added at idle (to make the idle stronger), it must be subtracted from the mechanical (RPM based) advance to achieve proper part throttle and full throttle ignition timing.  If this adjustment is not made, detonation and resultant engine damage is possible. 

Proper ignition timing is dependent on compression ratio, combustion chamber design, air/fuel ratio at various loads and speeds, exhaust scavenging characteristics, and vehicle power-to-weight ratio.  These factors all affect flame speed in the combustion chamber and when the ignition should be fired to maximize combustion pressure just after TDC. 

Determining proper ignition timing at idle and under all part throttle and WOT conditions is extremely complex and should be handled by an experienced "tuner."  It is not unusual to require several "tuning adjustments" before a timing "curve" is "dialed in."  This is a situation where patience and perseverance can pay huge dividends in performance and dependability.

 

 

WHAT EXACTLY IS "LSA" OR LOBE SEPARATION?
HOW DOES IT AFFECT THE POWER CURVE?

·         Lobe Separation -   Lobe separation is the distance in camshaft degrees that the intake and exhaust lobe centerlines are spread apart.  This separation changes cylinder pressure and determines where peak torque will occur within the engine’s RPM and power range. Tight lobe separations, such as 106°/108° or shorter, will increase cylinder pressure, causing peak torque to build earlier in the RPM range and peak-out in a short amount of time.  This is great for dirt track racing, so the car comes out of the corner hard.  The shorter lobe separation will also give that rough idle everyone loves to hear.  A broader lobe separation, such as 112°/114° or wider, will reduce cylinder pressure.  This causes the torque peak to come in later in the RPM range, but also allows the torque to build over a wider RPM range, giving you more mid-range and top-end power.  This type of lobe separation is needed in many applications, such as fuel injected, nitrous and blower applications.

 ·         Torque  -  From a driver's perspective, torque is the only thing that a driver feels, otherwise known as “seat of the pants,” and horsepower is just sort of an esoteric measurement in that context.  Three hundred foot pounds of torque will accelerate you just as hard at 2,000 RPM as it would if you were making that torque at 4,000 RPM in the same gear.

  ·         Horsepower  - In contrast to a torque curve (and the matching pushback into your seat), horsepower rises rapidly with RPM, especially when torque values are also climbing.  Horsepower will continue to climb, even well past the torque peak, and will continue to rise as the engine speed climbs until the torque curve really begins to plummet, faster than engine RPM is rising.  However, horsepower has nothing to do with what a driver “feels.”

 The technical term: the moment of a force; the measure of a force's tendency to produce torsion and rotation about an axis, equal to the vector product of the radius vector from the axis of rotation to the point of application of the force and the force vector. 

Or, in layman’s terms, (quoted from one of our techs.), "torque is what breaks the nut loose; horsepower is how fast the nut comes off "

CONFUSED YET?    NO?   GOOD?    THEN LET'S GO A LITTLE DEEPER

Cam Timing

 Cam advance, lobe separation, lobe centerline, intake lobe centerline, etc. are all terms being used for comparing and devising camshaft specifications.  With so many similar terms being used, there can be a bit of confusion when folks from different backgrounds start talking about them. 

Lobe separation is the measurement in CAM degrees between the maximum lift point of the exhaust lobe to the maximum lift point of the intake lobe on any cylinder.  Some also refer to this as lobe centerline.  This dimension is ground into the camshaft and cannot be changed by advancing or retarding the camshaft (unless it's an engine with separate intake and exhaust cams). 

Intake lobe centerline, or intake maximum lift, refers to the distance in crankshaft degrees from the cylinder's Top Dead Center point to the maximum lift point of the intake lobe.  This is usually measured as degrees After Top Dead Center.  This figure WILL change when the cam is advanced or retarded.  As you advance the cam, this number will get smaller, as you are opening it fewer degrees AFTER Top Dead Center.  Retarding the cam will make this number larger, as you are opening it more degrees AFTER Top Dead Center. 

Exhaust lobe centerline, or exhaust maximum lift, is usually expressed in crankshaft degrees Before Top Dead Center.  As you advance the cam, this number will get larger, since you are opening it more degrees BEFORE Top Dead Center.  Retarding the cam will make this number smaller.

 The average of the intake lobe centerline and the exhaust lobe centerline should equal your lobe separation.

The cam timing figures (as measured at a specific lobe lift: .004", .020", .050", etc.) may show the maximum lift point to be distorted when you're dealing with non-symmetrical camshaft lobes (the opening side has a different shape than the closing side).  If you split the difference between the opening and closing figures at .020" or .050" lobe lift, this figure will not coincide with the actual maximum lift point of the lobe.  There are instances where a non-symmetrical intake lobe is paired with a symmetrical exhaust lobe (or vice-versa), or lobes with varying amounts of non-symmetry may be used as intake and exhaust.  We believe that where the opening and closing events actually occur are the most important figures to pay attention to when degreeing your camshaft.  Just finding the maximum lift points doesn't really tell you anything about the camshaft, or if it's even the correct camshaft!  By documenting the opening and closing numbers as you tune, you will gain more knowledge as to what actually helps or hinders your performance.  This is also a good time to emphasize keeping track of your cranking compression whenever you change valve lash, cam timing, rocker arm ratio, and especially when changing camshafts.   

You may have noticed that most VHP / Crane cams have a certain amount of advance ground into them when you check out the camshaft specification card.  This is primarily done to insure that you have adequate torque to establish a good performance baseline.  We have also found over the years that the correct camshaft for most applications will run best with some amount of advance in it.  We believe that it's certainly better to begin with too much bottom end and mid-range torque, and tune from there, than to have a shortage of torque, and try to figure out how to compensate for that.

 

 ROCKER RATIO

Good Stuff Happens When You Increase Your Rocker Ratio  -  When changing rocker arm ratios on your engine to a higher ratio, not only does the gross valve lift increase, but the duration at the valve in the higher lift ranges also grows.  Aside from the usual valve spring/retainer travel considerations, your piston-to-valve clearances will now be reduced.  Please check and make certain that you have sufficient piston-to-valve clearance before starting your engine after increasing your rocker arm ratio.  Don’t guess at this  -  check it!

 

DOES HEIGHT REALLY MATTER?
 
When it comes to valve spring installed height, it really does matter.
Installed height is the dimension measured from the bottom of the outer edge
of the valve spring retainer where the outer valve spring locates, to the
spring pocket in the cylinder head, when the valve is closed.
 
Why is this important?  The installed spring height is the determining
factor of what the valve spring "seat pressure" and "open pressure" will be.
Both our camshaft specification charts and the spring section of our catalog
show what the spring pressure will be at a particular installed height.
Spring tension may vary even within a production run, so we always recommend
that each spring be tested on an accurate spring tester prior to final
assembly.  Spring seat pressure can be adjusted to equalize tension or
pressure, so check our web site or our catalog for tips on changing
installed height.
 
Keep in mind you always need to run enough seat pressure to control the
valve action as it returns to the seat.  Obviously heavier valves require
more seat pressure.  Lighter valves require less seat pressure.  If you are
not sure, it is better to run slightly more seat pressure, not less.
According to the extensive testing we have done, heavier valve spring
pressures do not rob horsepower.  For every spring that is using energy to
become compressed there is an opposing valve that is already compressed and
full of energy, that offsets the energy being used to compress the opposing
spring.  Better control of the valves usually means significantly improved
power at top end

 

·         Let The Air Out  -  The Generation IV big block Chevy needs to have the front lifter oil gallery plugs modified by removing them and drilling a .030” hole in the center of the plug and then re-installing them. This hole will bleed off any air locked in the front of the galley oil passages. This air lock can cause the front lifters on both sides of the block to starve the oil supply up to the rocker arms, plus starving the lifters causing them to clatter.

 

ALERT!

IT HAS BEEN BROUGHT TO OUR ATTENTION, THAT SOME INSTALLERS HAVE FAILED TO PROPERLY TIGHTEN THE BOLTS ON THE ROLLER TIMING SETS. THIS IS A GUARANTEED FAILURE. PROPER TORQUING OF THESE AND ALL FASTENERS ASSOCIATED WITH ANY INSTALLATION IS THE RESPONSIBILITY OF THE INSTALLER. THE BOLTS WILL BACK OUT AND INTERACT WITH THE TIMING CHAIN WHICH CAUSES THE CHAIN TO BREAK. SERIOUS VALVE DAMAGE CAN OCCUR. THE INSTRUCTIONS CLEARLY STATE TO TORQUE THESE BOLTS TO 10 FT LBS. "WORD OF ADVICE!" ASK YOUR INSTALLER TO CHECK THE TORQUE ON ALL FASTENERS.

 

GET IN LINE

The basic engine building procedure that seems to be overlooked nowadays is making sure that the upper and lower timing chain sprockets are in line with each other. With incorrect alignment, the stresses created can easily lead to premature timing chain failure (and we all know the mess that creates), and if the misalignment is pulling the cam forward, the lifters can contact the adjacent cam lobes and journals, creating an engine full of debris, and again, failure. With a proliferation of aftermarket blocks and crankshafts, along with many different choices of timing sets (each having numerous thrust bearings and shim options),  it's difficult to assume that all will be fine. Even standard blocks may have had their cam thrust faces machined for one reason or another, and if that info is not passed on, there's another opportunity for disaster.  

To confirm proper alignment, install the crank sprocket (apply mild heat via submersing in hot water if necessary to ease installation), making certain that it is up against the register on the crank. Then install the upper sprocket onto the camshaft, including any thrust bearings, thrust shims, retaining plates, etc. Then install the camshaft (without timing chain) into the engine, torquing all fasteners as required. You may also want to install the front balancer at this time, to insure that the crank sprocket is being properly positioned. Place a straightedge against the front edge of the sprockets, and inspect to confirm that straightedge contact is continuous on the sprockets. If the cam sprocket is too far back, a thrust shim may be able to be added behind it to obtain proper alignment (you'll need to make sure that the lifters and lobes are still properly aligned if you use this option).  If this is not possible, a step on the rear of the crank sprocket may have to be machined to allow it to slide further back on the crankshaft.  If the cam sprocket is too far forward, the thrust surface on the rear of the cam sprocket may be machined (again check lifter to lobe alignment), the thrust face of the block may have to be machined (yes, engine disassembly time again), or a shim placed behind the crank sprocket to achieve alignment.  
There are numerous possibilities to correct misalignment, depending on the engine type and optional timing components that may be available. The main thing is to check this as early as possible in the engine building process, allowing you the time to exercise different choices to correct any difficulties.  Also, check to be certain you have sufficient clearance between the chain and the block casting, and the chain to the timing cover. With many of today's wider chains, space may be at a premium. Checking these factors will help allow your engine to have a good, long life. This is cheap insurance to protect your investment.    

 

TRUCK TECH TIP 
*         Do you know when to be "wild" and when not to?  Well if you are
driving a truck that is really an important decision.  Why? Because setting
up your truck for how you regularly drive it is really the "map" for your
set up.  From a daily driver to rock climber, to actual drag racing, your
plan for daily use will give you the right recipe for maximum performance.
 
While "race only" trucks will opt for max lift and duration, we recommend
that you build for maximum torque for a daily driver.  Trucks are beefy and
weighty and maximizing the torque will get it up and going quicker so that
your zero to sixty mph elapsed time is quicker even when more heavily loaded
or towing.  Be careful in selecting larger carburetion or intake manifolds,
high flow fuel injection, or headers, etc.  Remember that max torque comes
from maximum airflow velocity not volume!  Our advice is, unless you are an
all out racer, keep it "mild" and don't go "wild."  After all, mom will be
proud of you!
 
Pushrods: The #1 Cause of Valve Train Problems
 

Which VHP / Crane Lifter Do I Use?

 Want to give your performance a real lift?  The “right” lifter that is.  People always ask us - “How do I know which VHP / Crane lifter to use?”  Naturally, with three different lifter choices, we understand the dilemma.  The answer is really pretty simple.  The “Original Design” lifters were designed for “street-roller” and bracket racing applications where cam profiles aren’t as violent.  We recommend that you don’t exceed 600 lbs. of open pressure and limit valve spring seat pressure to 240 lbs. on bracket racing applications and 220 lbs. on endurance applications.

 “Pro-Series™” roller lifters are lighter than the original design to reduce parasitic horsepower loss through inertia.  These designs undergo rigorous Finite Element Analysis (FEA) that eliminates “weak” areas and allows the best design for performance possible.  The “Pro-Series™” roller lifters are made from either 1214 alloy or 8620-alloy steel, depending on application.  These lifters are ideal for drag racing applications with seat pressures up to 300 lbs.  For circle track and other endurance applications, we recommend limiting seat pressure to 250 lbs. and open pressures up to 700 lbs.

 The VHP / Crane “Ultra-Pro™” roller lifters are the best in the market today.  Made from the finest grades of alloy steel and carburized heat-treated right here in-house, the best just got better with the addition of the Mikronite® metal finishing process.  All “Ultra-Pro™” lifters undergo the Mikronite® process that increases the residual compressive stresses, “hardens” the metal’s outer surface, and imparts an even pattern of microscopic “channels” that promote capillary oil adhesion and thus superior lubrication distribution and friction reduction.  These roller lifters provide the absolute best combination of lightweight, ultimate strength and reliability.  These are the roller lifters to use in drag racing applications where seat pressures exceed 300 lbs, and open pressures are over 800 lbs.  They are also the roller lifter to use in short-track and / or endurance racing applications where valve spring seat pressures exceed 250 lbs. and open pressures are above 700 lbs. 

 So, the answer is easy  -  once you determine the valve spring seat and open pressures and what type of performance you desire, just insist on VHP / Crane’s fine line-up of roller lifters -  “the best in the industry.”

 

New "Premium" LS1/LS6 Dual Valve Spring, # VHP-833 Released by VHP & Crane Cams

 

VHP & Crane Cams are proud to announce the release of a new, "super-premium", LS1/LS6 spring for high performance applications.  Made of "super-clean", extra-high-tensile chrome-silicon wire, our new 833 dual valve spring features a higher spring rate and improved harmonics in the 6000-7200 RPM range.  The "super-premium" material assures very long life even with high-lift, high-RPM applications.  This spring will be the perfect compliment to our soon to be released "Quick-Lift" Shaft-Mounted Rockers for the LS1/LS6 engine family.  The higher seat pressures (137 # @ 1.800"; 157# @ 1.750" when using our spring seat locators) make it the perfect choice for supercharged applications where boost pressure on the backside of the intake valve reduces effective seat pressure.

 

With dimensions very similar to our existing VHP- 832 spring, the new VHP-833 spring uses our existing titanium retainers and spring seat locators. The specs for this new dual spring are as follows:

           

            O.D.                            1.237"

            I.D.                              0.655"

            Seat Pressure           137# @ 1.800"

Seat Pressure           157# @ 1.750" 

            Open Pressure          377# @ 1.150"

            Rate                            369 lbs./ in.

            Coil Bind                    1.080"

            Identification              1 Blue and 1 White stripe

            Max Net Lift                0.650

 

This spring does not replace our popular VHP-832 spring, but compliments it .  The new VHP-833 spring is intended for serious high performance applications where maximum reliability is required.  The existing VHP-832 is recommended for Pickups, SUV's and moderate performance applications. The dual spring design of both springs offers the maximum in reliability.  Introductory price! $439.99 


 < CLICK HERE FOR MORE INFO > 

From Crane Cams Newsletter #184

Crane LS1 Gold Race Rockers “Too Powerful!” for Daytona!

 At this year’s inaugural Grand American Road Racing Series races at Daytona International Speedway, Crane Gold Race rockers used on the LS1 powered Pontiac GTOs were declared illegal for competition because they provided “too much of a power increase!!” On their first runs in practice, the new GTOs (fielded by Spirit of Daytona Racing) were as fast as last season’s series-champion Mustang!  That was without any chassis tuning or other “tweaking.”  It isn’t good to be that fast “right out of the box” with a totally new vehicle.  Series officials decided that in the interest of keeping competition “fair and equal” to all brands, they needed to slow down the new GTOs.  They evidently had heard “rumors” that Crane’s “Quick-Lift” rocker arm geometry provided a significant horsepower advantage (14 - 15 hp at the rear wheels) over the stock rockers even with the same 1.7 rocker ratio.  As a result, they declared the use of aftermarket rockers “unacceptable” and mandated the use of stock rocker arms for use in the Grand Sport Series.

 

CRANE CAMS NEW POLY-MATRIX SHAFT MOUNT ROCKERS

Nice to see all of the interest in our new shaft mounts for the LSx engine family. The delay in the introduction has been the tooling for the new polymer-matrix composite bearings. Well the bearings just came in yesterday and we are completing the paperwork (instructions, packaging, etc) and hope to start shipping in a couple of weeks.

There will also be rockers available in 1.75, 1.85 and 1.9 ratios. These rockers feature the polymer matrix composite bearings in place of needle bearings. The PMC bearings are pressure oiled via the pushrod and a drilled pushrod seat. They are extremely quiet and extremely strong. The rocker bodies have a very low moment of inertia (partially achieved through the elimination of the steel needle bearings) and can handle open pressures in excess of 850#

These rockers are not direct "bolt-ons", because (in our opinion) it is nearly impossible to get a good rocker geometry with a true shaft mount rocker on the LS1/LS6/LS2 head design without head modifications. To achieve the proper geometry and get an improved "Quick-Lift" performance, it is necessary to mill the rocker arm bosses .170" so that the rocker stands can be placed lower to allow the rockers to operate in the proper arc. This is really no different than machining the rocker bosses on old SBC heads. Additionally, while the heads are being machined, we have supplied 3/8 diameter stand mounting bolts which necessitates drilling and tapping the OE 8mm holes to 3/8-16. This larger bolt diameter assures holding the stands in place even with extremely high valve spring open pressures! In spite of the milling, we were unable to fit these rockers under the stock valve covers and they will require a 3/4" thick spacer. The rockers will not be sold with pushrods but they will come with an adjustable checking pushrod to determine proper pushrod length. My guess is that 7.350-7.400" will be the length that most people will need.

As far as pricing goes, I'm in R&D and the sales people figure the pricing, but it is my guess that the "retail" price of these shaft mounts should be well under $1000.00: however, I have an agreement with the sales people...they stay out of R&D and I stay out of sales!!!!

As soon as I know what the pricing is, I will post it.

Finally, the way I have described the rockers and stands is with a machined and tumbled finish. (both the stands and rockers are a special alloy of aluminum). We will also be offering these rockers and stands with a Mikronite processing that will increase the strength of the rockers and stands by over 25%. This provides additional strength beyond what I have all ready described. Additionally, the Mikronite finish looks superb. It is not a coating, but a sophisticated finishing process that results in a "chrome-like" appearance but which also increases the residual compressive stresses in the outer layer and near surface substrate of the aluminum-vastly increasing strength and longevity.

We feel that these "Quick-Lift" Shaft mounts will be the ultimate rocker arm for the LSx family at a price well below what people currently think is the "ultimate shaft system".

Again, thanks for everyone's interest!

Mark Campbell
VP, R&D,
Crane Cams, Inc.

 

From Crane Cams Newsletter #175

We Bet You Were Wondering

 Vinci High Performance (www.vincihighperformance.com), long-time promoter of Crane Cams, took delivery of a brand-new C6 Corvette a couple of months ago.  Roger, Joe and Greg have been busy dynoing the stock 400 HP set-up and taking this new motor apart to check what fits and what is different on this latest version of the LS1/LS6 power plant.  Initially, before the engine was released, GM informed everyone they moved the cam sensor from the rear of the cam to the front.  Now, this wouldn’t be reason for concern if we were like every other performance cam company.  We would just wait to check it out.  Crane cams was the first core manufacturer to offer the original 8620 steel billet core for the LS-1, so we were extremely curious as to whether it would take a new core.  Thanks for Vinci’s forward thinking to buy a new C6 Corvette and answer these lingering questions.

 

Camshaft:

All our 144-prefix cams work

Valve Springs:

Our 144832-16 springs fit

Valve Springs:

Our 144833-16 (tall assembly height; 137 lbs. @ 1.800)

Titanium Retainers:

Our 144661-16 fit

Spring Seats:

Our 144460-16 fit

Roller Rockers:

Our 144750A-16 (1.7) and 144759A-16 fit

Timing Chain:

Our 144941-1 will not fit

Power Programmer:

Currently testing  – stay tuned

 

Can Rocker Arm “Weight, Mass, and Moment of Inertia” Lead To Valve Float?

 For quite some time, rocker arm “weight” and its effect on “valve float” has been the subject of much debate among interested enthusiasts.   Unfortunately, many of the people making posts on the subject get “caught up in their underwear” because they don’t understand the difference between the terms “weight,” “mass,” and “moment of inertia.”  This misunderstanding has resulted in a great deal of misinformation being posted as fact on various web forums.  A very elementary explanation of what really happens follows. 

“Valve float” is a common term for a situation best described as “valve train separation.”  This occurs due to inertia load imparted into the valve train by the action of the cam lobe against the follower.  Flex in the valve train (the majority of which is located in the pushrod) is the prime contributor to valve train separation.  The initial loads imparted into the pushrod cause it to bend (somewhat like a pole vaulter’s pole) and then return to a straight configuration.  This unloads a sharp energy pulse to the rocker arm, which transfers it into the valve/valve spring assembly.  This often results in “valve lofting,” which causes the valve to operate in a different path than that described by the lobe profile.  At the same time, the lifter without any load against it, can also be launched off the opening ramp of the lobe and then, as load is re-established, either: strike the nose of the lobe and eventually damage it; land on the closing ramp (like a ski jumper landing on the slope of a hill); or land on the base circle with significant and often damaging impact.  If “lofting” can be controlled (by design or good fortune and the lifter lands gently on the closing ramp), it adds to area under the curve and more power.  If it is uncontrolled (which happens the vast majority of the time), it can be damaging to valve train components and will compromise performance.  Most of the time, power flattens out or is lost when “valve train separation” occurs.  Again, the biggest culprit in causing this situation is the flex of the pushrod.  In our tests at Crane, we have found 12 HP in a 350 Chevy with a 204/214 @ .050 cam (.420/.443 valve lift) just by going from a .065” wall pushrod to a .080” wall pushrod, and the springs were only 110# on the seat and 245# open! 

Many people on website forums tend to think that the “weight” of the rocker arm is the cause of valve float.  If the rocker is rigid and properly designed, it should contribute very little to valve float.  Weight in this case is not the prime issue, but rather the “moment of inertia” of the rocker design.  “Moment of inertia” is the affect of where the mass of the rocker arm is located relative to its center of rotation.  One rocker can be much heavier than another and still have a smaller moment of inertia because of where its mass is located; so weighing rockers to determine their affect of valve float is really not effective at all.  (FYI: “mass” is a measure of a body’s inertia; while “weight” is the affect of gravity on “mass.”  “Moment of inertia” is unaffected by weight, but is affected by where “mass” is located relative to the center of rotation!)  At VHP and Crane Cams, we design our rockers to be rigid (to minimize flex), and we design them to have a very low moment of inertia relative to the necessary strength.

 

Crane Gold Race® Rocker Arms Dominate Engine Masters Challenge

 

The 4th Annual Jeg’s Engine Masters Challenge, presented by Popular Hot Rodding magazine, was held this past week at World Products’ facility in Ronkonkoma, NY.  This year’s competition called for big block engines not to exceed 510 c.i.d.  When the battles were over, Lennart Bergqvist (Autoshop Racing Engines - Orlando, Florida) emerged victorious with his Crane Gold Race® rocker arm-equipped big block Chevy.  Runner-up Tony Bischoff (BES Racing Engines - West Harrison, IN) also relied on Crane rocker arms, as did two-time champion, Jon Kaase (Jon Kaase Racing, Inc, - Winder, GA) who came in fourth with his unique Pontiac entry.  Crane participated in the Challenge as a contingency awards sponsor, and Gordon Johnstone, a key member of Crane’s R&D team, was on hand to see what interesting approaches the participants had come up with for their entries.  The contest is based on an average of torque and horsepower over a 2500 to 6500 RPM range.  The winners took home $82,500.  Looks like Crane’s Quick-LiftÔ technology paid off!


 

CAM RETAINER PLATE WEAR

WARNING!

LSX  SERIES ENGINE CAM RETAINER PLATE WEAR PROBLEM

We have noticed a considerable wear pattern on the front of the camshaft retainer plate, on the all of LSX series engines, including  LS1, LS6, LQ4 etc trucks and on the new LS2 engines, as well. We believe this is due to improper oiling, between the plate and the timing gear.  (see picture 1).  This wear occurs with stock cams and after market cams as well, as it is a manufacturing defect not an aftermarket products defect. We have observed this wear on all of the LSX series engines with as little as 500 miles on them. VHP is bringing this information to our readers attention in hopes of preventing a serious engine failure. We have seen a material build up on magnetic oil pan drain plugs which, in some part, is due to the cam plate wear. We highly recommend using the Crane hex-adjust timing set on all cam installs, part number 144984-1.  The bearing at the rear of the cam gear prevents most incidence of wear from re-occurring . (see picture 2).  Here at VHP we have been notching the retainer plates for better oiling, to minimize this problem.  (See picture 3).  Upon tear down of test engines notching the plate and utilizing the Crane timing set has alleviated the problem.
 

PICTURE 1

timing gear side -  stock plate

PICTURE 2

notice the bearing on the Crane gear

 

PICTURE 3

timing gear side - modified plate
3-.0396" notches

 

 

·         LS1 Timing Chain And Gear Set

                                                               -  Part #144984-1.  Don’t let this happen to you. Our timing set comes with bolts and spacers.  Do not throw them out!  The spacers are there to move the oil pump away from the new, thicker Double Roller timing chain. Without these spacers, you will not be able to run our timing chain and gear set because you will have interference with the oil pump. The bolts, of course, are simply there to attach the oil pump.


 

         The Right Way To Use Adjustable Checking Pushrods to Determine Correct Pushrod Length  - 

     To determine the correct rocker arm geometry when using an adjustable checking pushrod on a stud mounted rocker arm cylinder head and a mechanical lifter cam, do the following:  Mount the complete cylinder head assembly on the engine, including the head gasket.  The cam needs to be installed with the lifters that will be used in the engine.  Mark the end of the valve stem with a marking pen or Dykem.  Install the adjustable checking pushrod and the rocker arm.  Adjust the pushrod so the rocker arm is as low as possible with the bottom of the rocker arm .060” above the hex of the stud or guideplate (whichever is closer).  Set the valve lash to the recommended setting and lock the adjusting nut.  Turn the engine over by hand until the rocker arm you are working with has moved a complete cycle.  Now, remove the rocker arm.  The roller tip of the rocker arm will have left a pattern on the end of the valve stem.  This pattern of movement should be close to the center of the valve but favoring the intake side of the valve stem.  If needed, adjust the length of the pushrod to achieve the correct pattern of movement.

The same process can be used with hydraulic lifters, but make sure the lifter is pumped up solid with oil.  The pushrod seat in the lifter should not move.  After one or two rotations of the engine, check to be sure the seat has not moved.  If so, pump it up and continue your procedure.  Once the correct length is determined, you can order the correct pushrods and maybe a couple of spares.

 

·         Coil Bind  - 

      mSome things are just forgotten or not worried about.  Your valve spring can be one of these forgotten parts.  Whether it’s a new cam install, a new valve job on an old engine, a change in rocker arm ratios, new heads, etc., you should always make sure that your combination works for the part(s) you install.  First of all, find out what is recommended for the part(s) you are installing, then take some measurements like “Installed Height” of the springs you have, “Coil Bind” height and the I.D. and O.D. of the spring seat.  If you insist on using the springs you have, you will still need to know where the springs coil bind and what spring pressure range you should be in so that you will not have “Valve Float” (too little spring pressure in this case) or “Coil Bind” (coils are actually smashing together).  Once you have your installed height and you know your coil bind height, make sure that you have at least .060“ extra cushion before coil bind.  This way you will have enough room for the spring to travel safely without the spring breaking or coming apart from being overworked.  To find this out, you will need to subtract your “Lift at the Valve” and .060” from your installed height.  (Example:  1.700” installed height / coil bind is at 1.100” / .500” lift at the valve leaves you with .100” extra travel before coil bind.  If you have a dual or triple valve spring, you will also need to make sure what the coil bind on the inner spring(s) will be.

 

Chevy High-Performance Magazine LS1 Project Truck Gains Average 20 HP

And 20 Ft. Lbs. Torque By Switching To Crane Gold-Race Rockers!

 It’s well known that switching from stock rockers to a full-roller, longer-ratio performance style rocker can deliver gains in both horsepower and torque.  CHEVY HIGH PERFORMANCE MAGAZINE Editor Ro McGonegal volunteered his “Red Dog Plan,” 2003 Chevy truck to find out how much.  After obtaining the Crane Gold-Race aluminum rocker kit (Part No. 144759-16, includes 1.8:1 rockers, lock nuts, screw-in studs, pushrod guideplates and stiffer, heat-treated chromemoly pushrods), Ro took the truck to Vinci High-Performance (105 Candace Drive, Unit 101, Maitland, FL 32751, 407/478-8388) for installation and comparative dyno testing.  The guys at Vinci also recommended replacing the stock LS1 “beehive” design valve springs with Crane dual springs and retainers (Part No.’s 144832-16 and 144661-16).  The Crane springs provide needed additional spring travel and pressure, (110 lbs. seat pressure, 350 lbs. open load) and they eliminate the operating “noise” commonly produced by beehive design springs.  This noise triggers the factory “knock sensor”, which retards spark advance, dramatically reducing power and torque output!  The “longer” rocker ratio increases gross valve lift, and the exclusive “Quick-Lift™” design of the Gold-Race rockers opens the valve quicker, beginning flow earlier.  On Vinci’s chassis dyno, the truck recorded “before” average numbers of 200.7 hp and 245.7 lbs. ft. torque.  After installation of the Crane parts, those numbers jumped to 219.9 hp and 266.5 lbs. ft. torque, an average increase of 20 hp and 20 lbs. ft. torque over the stock rockers and springs!  (Max torque came at 4,000 rpm and was 299.6 lbs. ft.  Max hp was 255.9, and that was recorded at 4,900 rpm!  That means the truck kept on pulling at a higher rpm than stock!)  Ro was especially impressed after he felt the very notable “kick in the butt” delivered by the added torque!   Whether it’s a full-sized Chevy or GMC truck, F-Body Camaro or Firebird or Corvette, GM LS series engines respond tremendously to the power increases delivered by Crane rockers, cams, valve train products, and the new Power-Tuner to fine-tune for max performance.  Our thanks go to CHEVY HIGH PERFORMANCE MAGAZINE Editor Ro McGonegal and Group Publisher Tom Voegele for giving our products a try.  The complete story appears in the CHP August Issue, pages 56-58, and on-line at: www.chevyhiperformance.com 

New!  Gold-Race Rockers For Air Flow Research “Mongoose” LS1 Cylinder Heads!

 Due to the increasing popularity of the Air Flow Research Mongoose series cylinder heads for the LS1 series of Chevrolet V-8 engines, we will now introduce two new Gold Race aluminum roller-tip needle bearing rocker arm kits for these applications, including all installation hardware.  This is because the AFR heads require pushrods that are .100” longer than those that come in our 144750-16 and 144759-16 kits. 

New part number 144750AF-16 will be the 1.7:1 ratio kit, while 144759AF-16 will be the 1.8:1 ratio kit.  These kits contain a full set of rocker arms and all of the installation components required, such as pushrod guideplates, rocker arm studs, adjusting nuts, etc. as our other popular LS1 kits.  Current suggested retail price for either kit is $836.00. Purchase them now from VHP for only $699.00.

VALVE TRAIN TIPS

More On Why Our Unique New “Quick-Liftä” Rocker Arm Geometry Makes More HP!

 There has been a great deal of dialog on several web forums pertaining to our "QUICK LIFT" camshaft lobes and rocker bodies. To set the record straight, this is what we have always maintained.

Here are a couple of questions about our rockers we would like to address.

  1. Does the varying rocker ratio adversely affect spring harmonics?
  2. Wouldn’t a fixed ratio rocker be easier on the valve train and cause fewer problems?

 The first point that needs to be made in answering these questions is that there is no such thing as a constant ratio rocker arm unless you are talking about a very limited range of lift (.150” or less).  This is because the pushrod seat end of the rocker and the valve tip end of the rocker are operating through two different distances and their ratio must constantly vary.  Traditionally, most rockers have been designed to start the valve off the seat and return it to the seat slowly.  (i.e. traditional SBC 1.5 ratio rockers started the valve off the seat at a ratio of 1.4 and did not get to a 1.5 ratio until .350” valve lift).  This was because many OE valves were made in two pieces, and quick opening and closing rates could compromise the valve.  The use of high quality, one-piece valves has made this a non-issue.  Many performance aftermarket companies, including Crane, tried to develop rockers that were as close to constant ratio as possible.  For instance, many 1.6 ratio rockers bring the valve off the seat at 1.62; by .250” valve lift, the ratio increases to 1.65 and by .550” valve lift, the ratio comes back to 1.61.  Again, the ratio is varying due to the different length of operating arcs of the end of the rocker.  Crane’s “Quick-Lift” design causes an “advertised” 1.6 ratio rocker to start the valve off the seat at a ratio of 1.72 and bring the ratio back to 1.60 by .250-.300” net valve lift.  This ratio is then maintained through the rest of the lift profile until the valve is within .250-.300” from going back on the seat.  It is then returned to the seat at a ratio of 1.72.  This geometry is illustrated in this diagram.

 Benefits of this geometry include more flow into the cylinder earlier in the cycle, quicker closing of the valve to trap cylinder pressure before combustion, more effective duration at .200” net valve lift while maintaining a relatively short seat-to-seat timing, and less valve spring seat pressure required because of the mechanical advantage of the higher seat ratio.

During development testing and now corroborated by more than two years of field-testing in competition, we have not seen any indication that the “Quick-Lift” geometry contributes to any additional valvetrain problems in any way.  In fact, the evidence so far shows that our “Quick-Lift” Polymer Matrix Composite Bearing Shaft Mount Rockers actually seem to reduce harmonic issues in the valve train and extend spring life.  At this time, we have no way of telling if this is the bearing construction or the geometry of the body or both!  One other important feature of these rockers is the absence of needle bearings, which can break loose under extreme valve spring pressures and cause catastrophic engine problems.  On average, we have eliminated 544 needle bearings from an engine with this design!!

 “Quick-Lift” rocker body geometry causes the rocker arm to be a dynamic component in the opening and closing rate of the valve.  Some people who don’t seem to understand this think it is “unnatural” to cause the valve to open faster than the cam lobe dictates, but OHC designs with finger followers have been doing it for years.  After all, aren’t we interested in what the valve is doing relative to the piston position?  Who cares how we get the valve there at the right time?  The point is that “Quick-Lift” rocker geometry will broaden the torque curve (torque x RPM/ 5252 = HP!!!) of any cam you use it with.  Our only warning: Super Stockers and others running extremely tight piston-to-valve clearance should check this with “Quick-Lift” rockers.   Try ‘em; we know you’ll love ‘em!!

VHP and Crane Cams have been working with each other for many years. Together, we have strived to provide the very best products we can with the latest technology available. We think, we design, we manufacture, we test....then we market the product. It seems that there has been much confusion about Crane/Vinci "Quick-Lift" cam lobes and "Quick-Lift" rocker bodies. We claim that the use of the Quick-Lift lobes with the Quick-Lift rocker bodies results in "effective valve lift" durations @ .200" valve lift equal to most other cam/rocker combinations using cams with 4-8* more duration at .050" cam lift. This is the result of the Quick-Lift Rocker body design. We do not state that our cam lobes (by themselves) give this advantage. The same laws of physics that limit every other cam designer limit our cam lobe designs. We attribute the advantage in valve lift to the "translation" properties of the varying ratio design of our Quick-Lift rocker body design. If you don’t believe us, test any cam lobe (Crane, Comp, Cam Motion, etc.) with stock LS1 rockers. Install a dial indicator on the retainer and a degree wheel on the crank. Plot a lift vs. degrees of rotation curve. Then install the Crane LS1 1.7 rockers (with the pushrods in the Crane kit) and plot the same curve. Measure the duration at .200" net valve lift. The Crane rockers will definitely provide more duration at this checking point. The reason for this is that, contrary to popular belief, the stock LS1 rockers are only 1.7 ratio above .480" valve lift. They actually start the valve off the seat at a 1.54 ratio. What do you think that ratio does to a "super fast" cam lobe? Slows it down quite a bit? The Crane rockers, properly installed, bring the valve off the seat at 1.79. Doesn’t take a math wiz here to see what combination is going to get open quicker and longer!! If you really want to see something interesting, take two lobes that have identical .050" seat-to-seat timing, identical .200" lifter rise timing, but one provides .583" valve lift with 1.7 ratio and the other providing .551 lift with 1.7 ratio. Plot a lift vs. duration curve with any rocker you want (other than Crane) and measure the duration at .200" valve lift. Then do a plot of the .551 cam with 1.8 Crane rockers (this will net out .583 also) and measure the duration difference at .200" valve lift. You will be impressed by how much more this second plot gives over the first. It’s also quicker on the drag strip! We’ve done this. Every person reading these threads can do something like this.

Our point is that the only thing that counts is what happens at the valve and the overall rocker ratio is fundamental to this. Contrary to popular belief, there are no fixed ratio rockers on the market (this is because the valve tip end and pushrod seat end operate on two distinctly different arcs). This is why some rockers add power and some don’t. Crane/Vinci have elected to do extensive development with rockers as a supplement to the lobe. The quickest lobe in the world doesn’t mean diddly if you are using slow acting rockers! Like everything else, it’s the combination that counts. FYI, the higher opening and closing ratios actually allow lower seat pressures because the mechanical advantage of the ratio helps maintain proper lifter preload! Check it out. This isn’t smoke and mirrors; it’s applied geometry and it works!! Roger Vinci

Quiet “ACCELERATED-LIFT’ Roller Rockers Are A Solid 17 HP Increase For LS1 / LS2 / LS6 Engines!

 ·         All of our LS1 rockers use  “barrel-shaped” roller bearings to allow more room for oil between the bearings to cushion the load and minimize the “sewing machine noise” common to most roller rocker arms.  The sewing machine noise is a noise that the knock sensor can interpret as detonation.  When this happens, the computer pulls timing out of the engine in an effort to eliminate the “detonation.”  The retarded timing costs horsepower.  VHP LS1 rockers are “quiet” to maximize performance without disabling the knock sensor (a performance “trick” that can destroy an engine).

 Electronically managed engines require “quiet components” and “innovative component designs” to provide significant performance increases compatible with the vehicle’s operating system.  VINCI HI-PERFORMANCE understands this and is working passionately to deliver the best valve train and electronics products for you and your customers.

Most Important Vehicle Factors in Selecting a Camshaft

 Our Tech Department is asked for cam recommendations literally hundreds of times a day.  Many people frequently ask, “What is the most important factor in making the proper cam selection?”  The most important factor is listening to the customer to determine what he/she wants from their vehicle.  Next to that, however, comes engine size, final drive ratio, tire size, vehicle weight and transmission type.  Engine size (including compression ratio and component types) is obvious, but most people do not appreciate the importance of the other factors in determining proper cam selection.  Operating under the assumption that most people want to maximize the performance of their vehicle (as opposed to just operating the engine at as high an RPM as possible), the tire size, combined with the final drive ratio, will determine the engine speed required.  For instance, a vehicle with a final drive of 3.42:1 and a tire diameter of 26” will only see about 5400 – 5600 RPM through the lights in high gear in a quarter mile run.  Selecting a cam that will make maximum power in the 2500 – 5600 RPM range will provide the best ET.  MPH might be higher with a bigger cam, but ET will suffer.  This is because MPH is related to peak horsepower, but ET is related to best average torque in the RPM range.  Heavier vehicles require a cam with more low end torque than lighter vehicles because it is much more difficult to get a heavier vehicle moving.  Automatic transmission vehicles require a camshaft that has idle and low RPM characteristics compatible with the torque converter to be used.  Stick shift vehicles must have attention paid to the first gear ratio and the average RPM drop between shifts.

 Many people mistakenly think other engine modifications are more important, but this is false thinking.  The camshaft is the “gatemaster” to the flow into and out of the cylinder, but this and all of the other engine components must be matched to putting the power in the RPM range that the drivetrain can use.  Once the camshaft is selected, modifications to components on both the intake and exhaust must complement the system.  It is no good to have a high flow intake system (large throttle body, high-flow intake manifold and custom cylinder heads) if the exhaust can’t get rid of the combustion products.  Proper cam selection takes years of real world experience, which often resulted in as many failures as successes.  Let’s face it, you often learn more from your failures than your successes.  At VHP, the people on hand to answer your technical questions have combined experience in the performance aftermarket of over 100 years!  Call us with your questions; someone around here either knows the answer or knows where to get it!

 

Quality Steps. . . Or How Lobe-to-Lobe Accuracy Affects HP And Durability!

 There are many parts in the internal combustion engine that can affect engine performance and fuel economy.  The primary part is the camshaft.  Cam lobe design directly affects valve train performance (the mechanical movement of the valves), which determines optimum horsepower and fuel consumption.  Cam lobe design (shape), dowel pin timing and lobe-to-lobe phasing are camshaft properties used to increase engine horsepower or fuel economy.  Increasing both is ideal.  Cam lobe shape is determined by lift, duration, acceleration, velocity and cam jerk, as related to its intended usage. 

 Lobe Separation  -  Lobe separation is the distance in camshaft degrees that the intake and exhaust lobe centerlines are spread apart.  This separation determines how peak torque will occur within the engine’s RPM and power range.  Tight lobe separations, such as 108° or shorter, will cause the peak torque to build earlier in the RPM range and peak-out in a short amount of time.  Broader lobe separations, such as 112°, will start making that torque peak later in the RPM range, but this allows the torque to build over a wider RPM range. Broader separation angles produce increased idle vacuum for more stable, cleaner, idles and better low end performance. They allow for easier tuning, as well.

Lift is the distance from the cam lobe base circle to the highest point on the cam lobe.

 Velocity is the rate of change of lift expressed in inches per degree.  Two of its uses are to define how fast (degrees of rotation) lift deviation can occur on quality checks and to track the contact point between the follower and cam.

 Acceleration is the rate of change of velocity and is used to determine inertia loads on the cam and valve train.

 Jerk is the rate of change of acceleration and is an indicator of how fast inertia loads are applied. 

Dowel pin timing is the radial relationship of the camshaft to the crankshaft installed in an engine (assuming that the crankshaft and timing set are properly manufactured).

 As to the process of cam lobe-to-lobe phasing.  Lobe phasing considers the lifter bank angle (the angle of the lifter bores to the engine’s vertical centerline, as in a “V” type engine) and the required activation (timing) of the intake and exhaust valve within each cylinder.  Normally, the bank angle is a given for a particular engine configuration (Ford, Chevrolet, Chrysler, etc.), while the valve timing can be altered to gain horsepower or fuel economy. 

 The Original Equipment Manufacturer (OEM) determines the original lobe centerline.  For example, for a stock small block Chevrolet engine, the valve centerline may be 112 degrees, meaning from the time the exhaust cam lobe is at top dead center (straight up, maximum lift), the camshaft would need to be rotated 112 degrees to bring its intake cam lobe to top dead center for any one particular cylinder.  Since nothing is perfect all the time, a tolerance to this specification of 112 degrees is applied - +/- 0.25 degrees or 15 minutes.  This tolerance is applied to all branded and private label camshafts.  OEM customers may specify something different, i.e., +/- 0.5 degrees.

Crane Cams grinds our  camshafts in their Cam-O-Matic and Race Shop departments.  The lobe master tooling used (pattern) is uniquely different for each department.  The Cam-O-Matics use gangmasters, while the Race Shop uses individual plate masters.  Gangmasters are one solid piece of steel billet with as many lobes on it as the camshaft to be ground (possibly including the fuel pump lobe).  The dowel pin and valve centerline timing requirements are built in to this tooling, which is manufactured and heat treated right there at Crane. The plate master is the shape of one cam lobe; the operator will orient the plate master to generate the dowel pin location and valve timing of each lobe as specified.

 Upon completion of producing this tooling, using a variety of precise NC machines in temperature-controlled “clean room” environments at their facility, it is checked on their Adcole-911 cam checking instrument.  Both shape and cam lobe centerline are checked, as well as size, concentricity and shape.  Upon passing this inspection, the tooling is released to production for use.