Noisy valve train
Noisy valve train Been dealing with a noisy valve train for some time and finally getting around to wanting to try to get it quieter. My build is a 2009 L76 with LS3 take out cam shaft, 12610046 head gaskets, 12499225 lifters and 7.400” (measured with calipers) stock pushrods, stock CTS-V exhaust manifolds, non milled heads AFAIK. All DOD/AFM was intact before I did the LS3 cam swap. Car runs like a scalded dog just noisy. I ordered the pushrod checker tool and should be here tomorrow. Anyone have any insite on this, what’s recommended preload on the 12499225 lifters. Any help is appreciated…
Joined: May 2004
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From: Halfway back on the Highway to Hell...again!
Are these actual GM LS7 lifters or LS7 "Style" lifters? The style is the keyword. Some aftermarket lifters require more preload to keep from chattering.
Or you may need to check pushrod length to get proper preload.
Or you may need to check pushrod length to get proper preload.
Last edited by SAPPER; Nov 22, 2021 at 03:42 PM.
TECH Senior Member
Joined: Jun 2016
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From: Central Cal.
I bet he has bogus LS7 lifters. GM used the same pushrods for all non-LS7 engines, including after they started using LS7 lifters in all other engines.
IF this is a stock LS engine, with genuine LS7 lifters, stock 7.400 (nominal) pushrods should work noiselessly.
IF this is a stock LS engine, with genuine LS7 lifters, stock 7.400 (nominal) pushrods should work noiselessly.
Joined: May 2004
Posts: 1,593
Likes: 267
From: Halfway back on the Highway to Hell...again!
I am sold on GM lifters from CamMotion. Bobby hooked me up with TRUE GM lifters. Even destroyed my price I get at work at the dealer for the same p/n.
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I get ONE turn of preload after zero lash with the stock 7.400” pushrod. From what I’ve been reading that is not enough for LS7 lifters. I ordered 7.425 PR to see if they will quiet down some. Will report back with results…
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TECH Enthusiast
Joined: Mar 2005
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From: South Carolina
If you didn't pay around $375+ for the "LS7" lifters they're probably the bulk Delphi $120ish lifters. I had a set of the bulk lifters on a 228/230 cam and they had the annoying sewing machine noise. Upgraded to a bigger camshaft with Morel 6504 lifters and the valvetrain is almost silent vs the bulk LS7 setup.
Joined: May 2004
Posts: 1,593
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From: Halfway back on the Highway to Hell...again!
Or find yourself an old 87+ gen 1 roller motor and take lifters from it. The original Delphis never died. LOL I have 2 engines with the originals in them. They'll last forever. 
Keep me posted, as I went through this same exercise a few months ago. It was determined that I needed 7.425" push rods, but after swapping them out there was no change in the sewing machine noise. It's interesting that you are running stock manifolds because I was thinking that it was possible my headers which I've used on multiple engines in the same vehicle were to blame. Had the same noise with an LS1 and now with my 6.2.
Although I only have about 2hrs of idle time on my 6.2 L94, it is very quiet with the same lifters, STG2 BTR cam and BTR dual springs. I am running 7.425 pushrods which was exactly the midpoint of travel for the lifters (which I measured with a dial indicator). Hopefully it stays quiet.
Update UPDATE:
I received the 7.425” pushrods today and installed them. The valve train is very quiet now. All I hear are the injectors snapping until I put my engine cover on and that noise almost completely goes away. Now off to the tuner to get this trans dialed in. thanks for all the help…
I received the 7.425” pushrods today and installed them. The valve train is very quiet now. All I hear are the injectors snapping until I put my engine cover on and that noise almost completely goes away. Now off to the tuner to get this trans dialed in. thanks for all the help…