[Guest]

I have my crane cam spec card but I can't seem to figure out the lobe separation and cam overlap? Does anyone know what numbers are required to figure this out?

 

[Guest]

If you have one you can figure out the other, assuming you know duration. Without either one you'll need to know the opening and closing points or points of maximum lift relative to the engine cycle. What does the cam card include?

Ollie

 

[Guest]

Its a crane solid cam 238/248 [email protected] intake opens at 16 BTDC closes 42 ABDC, exhaust opens at 57 BBDC and closes 11 ATDC.

 

[Guest]

Valve overlap happens around the TDC point between the exhaust and intake strokes. Your cam opens the intake 16 degrees BTDC and closes the the exhaust 11 degrees ATDC, add them for 27 degrees of overlap relative to the crank.

You have to assume that maximum lift happens exactly midway between opening and closing when figuring lobe separation. It's a pretty good generalization. This gives 217 crank degrees, that's 109 camshaft degrees.

Ollie