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Discussion Starter #1
6.0/5.3 question, LS7 lifters: #12499225 can you use stock length pushrods with these lifters?

Ive seen conflicting answers while searching through older threads.

Im ready to order the pushrods and lifters at the same time only to find out I spent $100 on the wrong length pushrods.

Thanks
 

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No personal experience but a friend used shorter pushrods (7.350) when he switched to LS7 lifters because that's what he read they needed. He had a lot of vavletrain noise and concluded he needed longer pushrods for more preload on the lifters. He went back to a stock length (7.400) and it's been fine. He's got a 347 and I think TFS heads
 

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^this. That's the only way you're going to get it right. I have LS7 lifters in my car and use a 7.375" pushrod. The heads are milled, but since I got them second hand, I don't know how much. That is the only way to satisfy the correct lifter preload requirement IMHO.
 

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Discussion Starter #6
Can someone describe the procedure?

I've never worked with an LS valve train before.
 

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Discussion Starter #7
I should say that the heads are not milled and I will be using stock valvetrain.
 

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generally 7.4" should be fine for your app but i would check the length to be sure. a checker pushrod is only like $20
 

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with stock unmilled heads i would think 7.4s would be fine also.

a push rod checker would be placed in the place of one of your pushrods. you would tighten the rocker arm down then adjust the pushrod checker up to take up slack. then from there you would need to figure out how much longer you would need to pre load the lifter
 

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LS motors have fixed rockers, you adjust the preload by longer/shorter pushrods instead of loosening/tightening the rockers. That being said, LS7 lifters should be the same physically as any of the truck lifters. In a 1:1 swap, you shouldnt need to adjust anything.
 

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You know how you get a longer or shorter pushrod on a SBC to get a good wipe pattern? Same procedure. You're looking for .030-.050" preload, so what I do is get the cam on the IBC and measure what it takes to get zero lash. Add the preload to that, and that's the length pushrod you want.
 

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No personal experience but a friend used shorter pushrods (7.350) when he switched to LS7 lifters because that's what he read they needed. He had a lot of vavletrain noise and concluded he needed longer pushrods for more preload on the lifters. He went back to a stock length (7.400) and it's been fine. He's got a 347 and I think TFS heads

I think you are talking about me!:supz:

I measured the pushrod length and determined that it should have been 7.35". This gave me a preload between .060-.070". Closer to .060" on the intake and .070" on the exhaust. The lifters were noisy as hell on first startup, so I put my old 7.4" pushrods back in. I checked preload again while swapping them and verified it to be .120-.130". Everyone will say that's too much but it's what they took to run quietly.

If you are running stock heads, gaskets, and rockers then I would not even waste the time checking pushrod length. Do like everyone did before someone on the internet told them they should check pushrod length and put the 7.4's in.
 

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Hey Dan! I bought a pushrod checker and measured to be sure, but with unmilled ls3 heads and ls7 lifters 7.400 gave me like .035" preload IIRC. Might have been .040"
 
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