Cam centerline question
 

There are 2 ways to measure this. (maybe a third) I can go by I & E opening and closing points, then find the two centers, subtract and divide by 2 - OR I can find the I & E points of max lift, subtract and divide by 2.
My cam has very gentle opening and closing ramps (especially the closing side) so the opening and closing points get stretched out a lot. I'm afraid that won't be a "real life" centerline if calculated that way. Due to the late closing, I get 16deg retarded on the cam centerline.
IF I use the max lift points, I get 5deg retarded. OR............I could use opening and closing at say, .050" lobe lift.
Which would be the best "real world" way to know how to predict what rpm the cam makes its torque? Do the beginning of the ramps really have that much to do with it? I think their purpose is to just take the shock out of the lifter acceleration.

Thanks
Verne

Find true top center of cyl#1 and zero degree wheel
Dial indicator on #1 intake lifter and rotate engine to find max lobe lift
Zero indicator at max lift
Rotate additional .050" and mark wheel
Rotate counter clockwise to .070" to remove chain slack and then back to clockwise to .050"
and mark wheel
Add 2 #s together and divide by 2
This is how we do all the engines at our shop and how I tell all my cam customers to do it regardless of cam type
Remember you must use a SOLID LIFTER during this exercise sir
Thanks
Nick @ Brian Tooley Racing

Opening and closing points and lobe centerlines should match the cam card either way you degree it. If they don't, you need to contact your cam grinder to find out why.

OK, So your suggestion is to do it at .050" lobe lift, centered between opening and closing. Thanks. I'll check that and see how it compares to using the two max lift points.

Verne

Eric, My cam card is from 1965 and doesn't have that information. And it's no longer available from Crower.

Verne