Stovebolt.com Forums The Shop Area The HiPo Shop Analyzing cam data

I've been asked "I have the valve opening & closing points of a cam, but how do I calculate the intake and exhaust centerlines, and the LSA or lobe center angle?"
Using the McGurk #18 data:

For the intake lobe: (intake closing - intake opening) / 2, then add 90 degrees
Example for 10-55 timing: 55 - 10 = 45, divide by 2 = 22.5, add 90 = 112.5 degrees ATDC

For the exhaust lobe: (exhaust opening - exhaust closing) / 2, then add 90 degrees
Example for 72-32 timing: 72 - 32 = 40, divide by 2 = 20, add 90 = 110 degrees BTDC

LSA: (intake CL + exhaust CL) / 2
112.5 + 110 = 222.5 / 2 = 111.25 degrees

I just wrote an Excel spreadsheet that calculates this automatically from your input, e-mail me for a free copy: jdiamond (at) optonline.net

Good school Panic, only thing missing is how to determine cam advance ground into the cam.

Use this site, https://www.blocklayer.com/degree-wheeleng.aspx to build your custom degree wheel. Just add the data from the cam card, and you have a degree wheel just for that cam!

Thanks, Joe! Added to my "favorites" list!

BTW- - - -has anybody else thought about drilling and tapping the snout of a stovebolt cam and using a harmonic balancer installer to push the timing gear on?
Jerry

Typically the suggested (or already selected) intake lobe center is 4 degrees advanced from the CL.
More advance closes up the intake valve-to-piston clearance, more retard closes up the exhaust-valve-to-piston clearance.
Overlap and LSA are constants (at least, in single cam engines!).