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. |
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%. |
sorry about that, yes i meant stock length. |
forgot to mention i'll be install new ls7 lifters. been reading about the preload on them is different or something like that. |
Nope, its the same. That's a myth that just won't die. |
ah okay haha gotcha. i'm new to this so i've been doing lots of reading on here and been seeing that a lot |
Originally Posted by 01ssreda4
(Post 17387963)
Nope, its the same. That's a myth that just won't die. |
5 Attachment(s)
Originally Posted by poltergeist 02
(Post 17388135)
This is wrong. I have personally measured LS7's and stockers with a dial indicator and ther is a .050" difference. The LS7 lifters are .050" taller. Zero'd with 2.500 blocks Attachment 609113 Extended over .3125 ball Attachment 609114 Collapsed over .3125 ball Attachment 609115 All of them Attachment 609116 Attachment 609117 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" |
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? |
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. |
Originally Posted by luisdavid11
(Post 17388381)
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? |
Originally Posted by poltergeist 02
(Post 17389808)
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. |
pick up my 241 heads from machine shop...so this is my ??? he milled the heads 40 thousandths is that too much i know i have check pushrod length but is thier anything else i need to check |
Originally Posted by new2dgame
(Post 17400174)
pick up my 241 heads from machine shop...so this is my ??? he milled the heads 40 thousandths is that too much i know i have check pushrod length but is thier anything else i need to check |
^^No he won't. Intake will seal fine. |
Originally Posted by luisdavid11
(Post 17389879)
will do. thanks man. |
Originally Posted by 01ssreda4
(Post 17387963)
Nope, its the same. That's a myth that just won't die. |
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