pushrods and milled heads
pushrods and milled heads would i need shorter pushrods with .030 milled 317 heads on an lq4 with stock gm head gaskets and a 228/228 .588 .588 110 lsa cam and set of new ls7 lifters ? or will some comp cam hi-tech 7.4 pushrods work fine ?
thanks in advance guys.
thanks in advance guys.
Last edited by luisdavid11; May 10, 2013 at 12:37 AM.
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From: Turnin' Wrenches Infractions: 005
Stock pushrods won't work, they're weak enough as is and can't handle an aftermarket cam. If you meant stock length, well you may be ok. Here's why: Typically stock pushrods are right at 7.40, and aftermarket cams are smaller then stock cams and usually require a slightly longer pushrod, say 7.425. Now if you milled your heads .030 then that puts you right back at the 7.40 range with stock preload levels. I would however double check the measurement with a pushrod checker just to be 100%.
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On The Tree
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Zero'd with 2.500 blocks
Extended over .3125 ball
Collapsed over .3125 ball
All of them
Measurements
1st set of pictures: 2.6511" extended; 2.4478" collapsed. Total travel of .2033"
Bottom pic from left to right...(the 2 missing measurements weren't listed because the piston wouldn't move from sitting for years)
Sample part #1 (part 1): 2.6588 extended length; 2.4565 collapsed length. Total travel of .2024"
LS7 sample #2 (part 4): 2.6562" extended length; 2.4486 collapsed length. Total travel of .2076"
Sample part #2 (part 5): 2.6491 extended length; 2.4565 collapsed length. Total travel of .1926"
Last edited by Havoc40; May 10, 2013 at 08:12 AM.
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Brett Foote wow good info, Havoc. So what you're saying is that by milling the heads .030, I should be fine with the 7.4 correct? If i had stock heads, i'd need bigger rods, 7.425 due to the ls7 lifters, but since I'm milling, the 7.4 should be fine?
On The Tree
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Like 01ssreda4 mentioned, due to cam base circle variations and a multitude of other variables, when something is changed in the valve train you want to measure. That way you won't have to start another thread about noisy or broken components in the valve train. You might be just fine with 7.400, but is it worth the risk not to measure? I know I can't sleep at night with things like this rolling through my head. Just something to think about...
yeah i got you. rather spend a few bucks in a $20 length checker than live with the fact that i messed up an engine due to a $20 tool lol. nonetheless, thanks for the input guys. i appreciate it.
No, buy a pushrod length checker and see for your self that your 7.4's are too long for your set up. You will most likely need 7.35 - 7.375 pr's but you should measure to be 100% sure.
You might have trouble getting the intake manifold to seal up with .040 off, but opinion varies on this. Are you using GM MLS gaskets, or a thinner cometic gasket? You should still measure for sure though. I ended up needing 7.375 length PRs with my milled 243s and F13 cam (new LS7 lifters and lifter trays)..
