OK, I've read probably every post on degreeing a cam but I still have some questions. First has to do with my cam card. Nowhere on my card does it actually use the word "centerline". It does say to "degree intake lobe to 108 checking clearance .050" (at tappet)". Is this the centerline? The only other number that would be close is the lobe separation of 110 but I'm assuming its the "108". Am I right? Using Jim Bureks degreeing method detailed in this post: v8buick.com/showthread.php?s=&threadid=16595 I came up with a centerline of 114. The card says Intake opens @ 7 degrees BTDC and I get a reading of 2. But the real problem is when I try to get my closing reading. The card says 43 degrees ABDC but my reading when I continue clockwise to .050 on the dial gauge is 162! What am I doing wrong? Am I not going far enough around? Should I go past .050 untill I hit it again. When I hit it the first time the lifter does seem to be pretty far away from the base of the lobe. Finally, Since we weren't sure of the correct centerline numbers (110 or 108) we decided to advance the cam 4 degrees to see if we came out any closer. After putting the crank gear in the +4 keyway we tried it again and came up with centerline numbers that were way off! At this point we gave up. Now granted its been 15 years or so since I've worked on cars but I've installed dozens of cams and timing gears straight up with no problems so I can't figure out way we can't get it to work out when we try to advance the cam. If we put the crank gear back on the "0" or straight up position we come up with a 114 centerline again but when we try to advance it (or retard it for that matter) our numbers are way off. What can we be doing wrong?! Thanks for any help on this. We should've had this short block assembled 3 times by now.
From the sounds of it, the cam is ground with a 110* centerline, but they want you to install it at 108*. If you are finding that the int. centerline is at 114*, you'll need to advance it 6* to get to your 108*. Hope I've got that right.
Mike, the lifter at .050 lifter rise is going to be just that , .050 off the base circle, both at opening and closing. From what you are describing on your intaek opening point, your cam is 5 degrees retarded, this would also mean your intake centerline is 5 degrees retarded. I'm not sure what cam you are using and which timing set you are using but I could probably talk you through it on the phone if youwant to call me. When the cam card says , degree intake centerline to 108 , or whatever, that is where you would get the .050 opening and closing points listed on the card. Jim Burek P.A.E ENTERPRISES 915-855-6009
Jim, Its one of Dave MacIntosh's custom grinds and is ground by Schneider cams and the timing set is a 9 keyway double roller. After stepping back and thinking about how the valve train works and why I was doing things instead of just following words on a page I think I've got a handle on it now (I think). The motor is at my friend's place so I think I'll go take another stab at it tomorrow. If I still have problems I will give you a call this week. Thanks again for your response. It seems I can always count on you. Hopefully someday, somehow I will be able to return the favor. Also thanks to you too Scott for your input.
