The Ford Barn

flatjack9 · 10-30-2012, 10:12 PM

I'm building an engine for a guy who bought one of Comp Cams Thumper series cams. Checked timing and the intake centerline is supposed to be at 102 deg ATDC and it came out 108 ATDC or 6 deg retarded. This cam is ground with 107 deg lobe centers(hence the thump). I'm sure it would have been a bit mushy on the bottom end if installed this way. They make a variable timing gear that is + or - 6 deg so I can correct the problem. Shows the importance of checking.

JWL · 10-31-2012, 04:53 AM

First, I agree it is very important to check the cam. But, I pay more attention to the actual closing number than the intake CL number. How does the intake closed number look? Just curious.

flatjack9 · 10-31-2012, 09:24 AM

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Also retarded 6 deg. Looks like the cam was meant to be ground with 6 deg advance and they ground it straight up. Exhaust center was also off 6 deg. The durations and lifts all check out.

10-30-2012, 10:12 PM	#1
flatjack9 Senior Member Join Date: May 2010 Location: Oshkosh, Wi Posts: 4,527	Check that cam I'm building an engine for a guy who bought one of Comp Cams Thumper series cams. Checked timing and the intake centerline is supposed to be at 102 deg ATDC and it came out 108 ATDC or 6 deg retarded. This cam is ground with 107 deg lobe centers(hence the thump). I'm sure it would have been a bit mushy on the bottom end if installed this way. They make a variable timing gear that is + or - 6 deg so I can correct the problem. Shows the importance of checking.

10-31-2012, 04:53 AM	#2
JWL Member Emeritus Join Date: May 2010 Location: Fitzgerald, Georgia Posts: 2,204	Re: Check that cam First, I agree it is very important to check the cam. But, I pay more attention to the actual closing number than the intake CL number. How does the intake closed number look? Just curious.

10-31-2012, 09:24 AM	#3
flatjack9 Senior Member Join Date: May 2010 Location: Oshkosh, Wi Posts: 4,527	Re: Check that cam Sponsored Links (Register now to hide all advertisements) Also retarded 6 deg. Looks like the cam was meant to be ground with 6 deg advance and they ground it straight up. Exhaust center was also off 6 deg. The durations and lifts all check out.