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Old 10-22-2011, 05:55 PM
millerrockers millerrockers is offline
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Originally Posted by cobalt327
So, if following the mid-lift scenario, at max lift am I correct in thinking the roller should be at a position more towards the intake side of the valve tip as I originally thought?

BTW, the Comp diagram uses "1", "2" and "3" for the positions of the roller across the tip of the valve, not "A", "B" and "C". So is your "A" above = 1, "B"=2 and "C"=3?

Thanks for your time.
Yes, and Yes. I only use an outside cam company link on the web site one time, and it is specifically this illustration at the Comp Cams site, and the link is used under the definition "WRONG GEOMETRY" in the Terms & Definitions page:

Click on "W" in the ALPHA bar to be taken to this last definition.

I am not trying slam Comp or anyone, but I am still and engine builder at heart, and I hate to see so many guys chasing their tails from BAD INFO from companies that KNOW BETTER.

I might add as I tried to emphasize in the prior post, measuring for what you're setting needs to be done accurately, and you can't do that with chasing symptoms. The roll on the valve, the Smokey Yunick "look at it from the side" routine, and blue-inking the valve tip for a pattern, only gets you close. The easiest, and most precise way to set up, is in the CLOSED valve position, by measuring where the trunnion (or shaft) axis is BELOW the roller tip axis. You want this to be exactly HALF of your NET VL. If you have .600" VL, then the trunnion needs to be .300" BELOW the roller PIN Centerline.

The TRICK (if there is one), is to measure at a PRECISE 90 degree relationship with the valve. The best way to do that, is the valve spring retainer, or the valve stem itself -- but that can only be for a shaft system, where you're setting up the STAND height. That can be done on a bare head on the bench. Then order your pushrods when the heads are all bolted up.

Not trying to do any selling here. Where I am directing you is FREE. So go to the INSTALLED geometry page of MID-LIFT, and look at the same illustration I published in the Lunati catalon in 1988, that remained for 12 years. It uses the technique I mentioned above. It will get the last .003" of an inch accuracy out of your system, and your CAM. Needless to say, you MUST order exactly the correct length pushrod, or it's all a waste of time. :-)

Maybe you've already been here, but here's the link:

Last edited by millerrockers; 10-22-2011 at 06:02 PM.
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