Hellllo again.
I was looking at Pat Kellys Page for Calculating Cam overlap Here (http://members.uia.net/pkelley2/Overlap.html)
When trying to figure out my overlap, my cam specs are at .050 or .020.
So heres what I did...
Part Number 12-512-5
Grind Number CS280TLS-6
Intake Exhaust
Lash .018 .018
Gross valve lift 530 550
Duration .020 280 288

Valve Timing Open Close
@ .050 Intake 19 BTDC 51 ABDC
Exhaust 56 BBDC 23 ATDC

Duration Intake Exhaust
.050 250 259
Lobe Lift .353 .366
Lobe Seperation 106.0

Ok i'm getting 72 Degrees over overlap...Is this correct even tho i'm using at .020??? and if so what does this mean exactly? i'm still learning cams here smile.gif
Thanks Guys
Ed Fletcher

With .018" lash the correct lift to measure duration is Lash/rocker ratio + .004". .018/1.5+.004=.016". The valve is off the seat at .020" so the duration is longer and the overlap is greater. Without knowing the lift rate of the cam, I know of no way to calculate what the actual duration or overlap is. You could put a degree wheel on and measure it. Just as a very rough guess, I'd say the overlap is about 80º. You didn't include the lash in your email so that answer isn't quite right.