check PTV withOUT pulling the head???
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From: pittsburgh, pa
check PTV withOUT pulling the head??? is there a way to check PTV with pulling the head off??? i never did it any other way before, i used clay on top of the piston but i always did by pulling the head off. right now i have a random set of ported 5.3 heads (not sure who did they work and specs) and a 224 cam. i want to put a TSP 233/239 cam in. kinda being lazy, i could pull the head but i don't really want to. can anybody help??
Yes. You need to install two checking springs and use an adjustable pushrod. By setting the pushrod at zero lash and measuring the distance the valve moves in increments just before through just after the piston reaches the top of the overlap stroke you can establish PTV. You should have a dial indicator as well. I actually think this is a better method than the clay method.
Staging Lane
Joined: Aug 2006
Posts: 51
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From: Suffolk, NY
McMaster-Carr has them but I would Google for the best price. If you buy one get a good one like a Starrett. The cheap Chinese ones are crap and the Starrett will last the rest of your life for an extra $50.
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From: BFE
You're still gonna need to yank the heads. Why because you need to measure with a modified lifter with welded cup (no internal spring). Otherwise your lifters are hydraulic and would have bled down giving false reading. Welded lifter mimics full lifter pump up at no preload (0 lash), so gives you maximum clearances.
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I have had good success with the hydraulic lifter but you need to use your fingers to feel for zero lash at each successive piston position (letting the plunger stay up top on the lifter) and then make the measurement to the piston. This is more difficult with new unfilled lifters but can be done.
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You're still gonna need to yank the heads. Why because you need to measure with a modified lifter with welded cup (no internal spring). Otherwise your lifters are hydraulic and would have bled down giving false reading. Welded lifter mimics full lifter pump up at no preload (0 lash), so gives you maximum clearances.
If you do it that way, why would it matter what kind of lifters you have? If I understand correctly, you're measuing how far down you can push the valve before it contacts the piston and then subtracting it from what's known about the cam.
Simply set piston at TDC, remove valve springs, measure free travel at the top of valve stem with dial indicator...record reading
With rockers removed rotate engine and measure lift of cam @ Piston TDC with dial indicator at the top of pushrod...multiply this reading by your rocker arm ratio 1.7 or1.8 (You CAN do this with the hydraulic lifter, lifter plunger spring is stiffer than dial indicator spring)...record reading.
Do the math and add .080" extra clearence for valve float.
With rockers removed rotate engine and measure lift of cam @ Piston TDC with dial indicator at the top of pushrod...multiply this reading by your rocker arm ratio 1.7 or1.8 (You CAN do this with the hydraulic lifter, lifter plunger spring is stiffer than dial indicator spring)...record reading.
Do the math and add .080" extra clearence for valve float.
Last edited by gollum; Dec 4, 2007 at 10:17 AM.
