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Old 08-19-2012, 08:25 PM
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First time: valve train geometry/mock up questions

I am mocking up the valve train to measure for correct pushrod length and I need some clarification from the pro's. I have read up a lot of valve train geometry lately and pretty much given up on the idea of setting up for midlift (smallest wipe area). Given my hardware I just do not think I can make it work, so I am just going for the center wipe.

First, here is my hardware:
  • SBC350, decked .020"
  • L31 Vortec heads, milled (.010" ?), OEM pressed in studs
  • Howard's Cams full roller rockers
  • Comp Camps XE274H (230/236 @.050", .490")
  • .026" Compressed thickness head gasket (although I am NOT using it in the mock up phase

When I tighten the polylock it is very clear when it bottoms out/zero lash is achieved. Is it from this point that I should go another 1/2 to full turn?

Where does the plunger on a hydraulic lifter normally operate at in a running engine (as in what height)? Doesn't it normally stay at the very top of the lifter, and when it is bumped by the cam it goes down a few thousands of an inch?

Right now I am getting a good centered roller wipe path with my adjustable pushrod set to 7.600". This "seems" short. When I tighten the polylock it is almost bottomed out on the stud shoulder. Is this normal/OK? Maybe I should consider lash caps? Are those OK to run in a street engine?

In this pic you see the where I am at with the 7.600" pushrod. The lightweight valve checking springs I got are pretty stiff. They are pushing the plunger on the hydraulic lifter down, so when I get to peak lift I use my hand to push the rocker down the rest of the way. I stop when the plunger reaches the top of the lifter. Is this OK?
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