Short of putting your cam on a computerised cam measurement device, the cam card alone reveals very little about the camshaft’s design. But in the real world, as many people on here know from first hand experience, cam grinds of this type have a tendency to wear cam follower bores and maybe trash other valvetrain parts. It should deliver a better spread of torque through the entire rpm range. On paper the faster accelerating cam looks good. The lower the figure, the faster the acceleration is between those two values. You can get a feel for how quickly these cams accelerate the cam off the seat by comparing their ‘running duration’ figures against ‘duration. Yes, it’s possible to come up with a design that accelerates the valve off the seat more quickly than most of the common cams and therefore has equivalent (or even more) area under the curve than a longer duration cam. Now take in to account the cam designer has no idea what type of valvetrain their cam will be used with eg, super lightweight titanium or heavy stainless valves with chromoly retainers etc etc. Then you have a third derivative, jerk i.e. But now the actual lobe design must be studied to ensure it’s suitable for use with the diameter of lifter being used (more velocity requires a larger diameter lifter) and whether the rate of change in velocity (acceleration) is likely to be kept under control by the valve springs. The cam designer will generally design the valve’s lift profile first, effectively working backwards to arrive at the cam lobe design, once rocker ratio has been decided.
Yes, switching from a 1.4 to 1.5 ratio alters duration as well as lift at the valve ( once it’s off the seat).Ĭam design is a very specialist subject – very few people understand it fully, myself included! In order to help you dial in the cam as they intended they must use a reference point that relates directly to the cam and not something that will give a multitude of different results dependent on type of rocker and how accurately (or not!) rocker geometry has been set up. In response to: not another camshaft threadĬam manufacturers have no control over the style of rocker assembly being used. Originally posted by John Maher on Cal-Look Lounge August 2010
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