Absolute Minimum Valve Clearance
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From: Milford, CT
Absolute Minimum Valve Clearance
Engine is a '93 351W, E7TE heads, Non-Roller Block. Putting it back together with a new cam, and was wondering what you guys feel is OK for minimum valve clearance, Intake and Exhaust. I'm looking for absolute minimum cold, paint on the cam and assembly lube between cam and lifter. I really don't want to have to get shorter push rods, and the clearance (compressed lifters) is about 0.022 (at least for the first one). Hayne's specs 0.112-0.175, and I don't think I want to stack that many shims (about 8 for the first one alone). Rockers are Proform 1.7, Cam is a Crane 444232, push rods are stock.
-Mike
-Mike
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From: Ottawa, Ontario
A little confused here.. what you're describing isn't the correct way to measure P-V clearance, and it's not necessary with this combination of parts anyway as there's nowhere near enought lift or duration to cause concern with a properly timed cam in a stock shortblock.
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Went ahead and ignored where Hayne's said they should bottom (aftermarket cam (doh)) and they all were fine. I know it shouldn't be an issue, but I wanted to check'em anyways.
-Mike
-Mike
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Apparently there are a few trick ways to do this but the one I'm familiar with requires the lifters to remain at full extension which means you either replace a set of valve springs with lightweight test springs or pack a pair of lifters so they can't compress, then clay the top of a piston, install the head, pushrods, rockers and torque everything down to spec, then rotate through a full cycle and tear everything apart to check how much the clay is dimpled. Is this what you were trying to do? I mean it's never a bad idea to check things out for you own sanity and to verify that you don't have something else like the cam timing all wrong, so I'm not suggesting you blow this off just trying to clarify and make sure I understand.
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From: Ottawa, Ontario
Ah oK.. and yeah that's totally different but again the test is done with a fully extended lifter. This video says it all... Valve lash adjustment on a 5.0L with pedestal rockers - YouTube
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From: Milford, CT
That would depend on what the spec was written for. The values I was comparing specified compressed lifter and measuring with a feeler. Some specs specify fully extended and the "rotate" method. Depends on who wrote it, you just have to make sure you use the right one.
-Mike
-Mike
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