Pushrods and ls7 lifter question
Pushrods and ls7 lifter question My motor will be back together this week, I have ls7 lifters now and wanted to know if I should expect the standard 7.4's to be to long? I've been hearing ls7 lifters change the pushrods length but I just felt like asking so I know what to expect ahead of time. Thanks
I will check, im just wondering what to expect since that means ill have to send them back to tsp for a different size ahah. How about this way, how many people are running 7.4's with ls7 lifters out there? My heads are not milled and from what I hear the ls7 lifters are the exact same size as the ls1 lifters?
If I'm not mistaken, the LS7 lifters are the GM replacement part for an LS1 lifter now, but they are NOT identical. I believe they require a slightly shorter pushrod than stock to achieve correct preload with an otherwise stock setup.
Again though, determining correct length for your application depends on multiple factors in your setup.
Again though, determining correct length for your application depends on multiple factors in your setup.
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Launching!
Joined: Jan 2008
Posts: 224
Likes: 1
From: Westminster, Md
Yes, you are correct, the LS7 lifters are .05 longer than stock LS1 lifters. This difference in length will require a pushrod of 7.35 to put you within the range of stock preload. Of course, some individuals have used a 7.325 pushrod to reduce valvetrain noise and change their lifter preload. I think your choice in a 7.35 pushrod will suffice. However, make sure to use the length checker to assure you are within a safe and reasonable preload. I believe the LS7 lifters operate best between a .06 and .09 preload. Different lifters (MOREL, COMP, LUNATI, LS7) operate better at different preloads and have different suggested preloads. However, the amount preload best for each individual engine is debatable. Hope this helps.
TECH Senior Member
Joined: Mar 2004
Posts: 14,620
Likes: 17
From: BFE
Yes, you are correct, the LS7 lifters are .05 longer than stock LS1 lifters. This difference in length will require a pushrod of 7.35 to put you within the range of stock preload. Of course, some individuals have used a 7.325 pushrod to reduce valvetrain noise and change their lifter preload. I think your choice in a 7.35 pushrod will suffice. However, make sure to use the length checker to assure you are within a safe and reasonable preload. I believe the LS7 lifters operate best between a .06 and .09 preload. Different lifters (MOREL, COMP, LUNATI, LS7) operate better at different preloads and have different suggested preloads. However, the amount preload best for each individual engine is debatable. Hope this helps.
See pics attached LS7 on left
Teching In
Joined: Nov 2007
Posts: 20
Likes: 0
From: Macungie PA
I've read .060 to .120 preload is acceptable. I measured 7.331 pushrod length at zero lash and went with Manley chrome-moly 7.4's that actually measured out to 7.411. Puts me right at .080. I have very mild valvetrain noise but then I am using Yella Terra ul's too. 
What would be the negative effects of running a 7.4" pushrod with the LS7 lifters? I just swapped heads and changed over to the LS7 lifters. I just reused my Manley 7.4" pushrods from my cam swap a few years ago.
TECH Senior Member
Joined: Mar 2004
Posts: 14,620
Likes: 17
From: BFE
If you go over that you run the risk of lifter damage, hanging valves open and even PTV contact.
Teching In
Joined: Mar 2006
Posts: 29
Likes: 0
From: Richmond VA
When I used the 7.4 rods I had ZERO static compression. Measured with rod checker and wound up needing 7.325 for .075 preload. (5.3 heads unmilled, MLS gasket, LS7 lifters, stock rockers)
I have the same setup except I used the GM Graphite gaskets. Looks like I may also need shorter pushrods. Could you explain the zero static compression to me?
Teching In
Joined: Sep 2007
Posts: 22
Likes: 0
From: dallas, tx
could you guys possibly see a 7.4 pushrod coupled with 1 ls7 lifter (only one was bad and I was told these are identical much like the other people in this thread) creating oil pressure issues? or is the lifter going to have to fail before i see oil pressure issues?