Lifter preload
Thread Starter
Melting Slicks
Joined: Nov 2011
Posts: 3,164
Likes: 258
From: Virginia
Lifter preload
What would be the max lifter preload to run on LS7 lifters to be considered safe? The reason I’ asking is because I am currently running 7.400 pushrods with my tsp 228r cam on stock 243 heads and the sewing machine noise is awful. I had a shop measure and I want to say it was a preload of around .085-.090 but I’m not positive. If this is true then would going to a 7.425 be a bad idea? I plan on buying my own adjustable PR tool and checking but I don’t know if mine currently are too long or too short. I believe a higher preload would equal less noise but I didn’t want to be on the red area of excessive wear. Could lowering the preload from what I currently have produce less noise?! If anyone wants a video let me know and I will send one, this is driving me nuts. I have the Straub trunnion upgrade and while it made have quietened overall engine bay motor noise a bit it did not help the sewing machine sound. Just by the sound of my motor holding the rpm’s steady around 2k something has to be off
Last edited by bwill03z; May 14, 2019 at 11:41 AM.
Burning Brakes
Joined: Oct 2016
Posts: 1,205
Likes: 363
From: Massillon Ohio
Ideally you want to measure preload with a solid lifter (a modded hydraulic lifter works for this). LS7 lifters have a very wide spread pre load range.. Anywhere from .020" to .120" of preload acceptable. Most like to keep them in the .070" range.
Burning Brakes
Joined: Oct 2014
Posts: 874
Likes: 107
From: Detroit MI
This is just my experience, and yours may vary...
I'm running a BTR stage 2 cam with LS7 lifters and 243's ported and milled just slightly. I started with 7.4" pushrods and the valvetrain was rather loud. I was measuring pre-load in the same range you are ~.090.
Since pushrods are "cheap" and relatively easy to swap, I ordered a set of 7.375 pushrods from BTR to bring the pre-load down a bit as an experiment. It was almost immediately quieter and has stayed that way for a few years now. Once the oil heats up it gets a bit louder, but not much. It's still noticeable though, my tuner said that's just how cammed LS1s sound.
I'm running a BTR stage 2 cam with LS7 lifters and 243's ported and milled just slightly. I started with 7.4" pushrods and the valvetrain was rather loud. I was measuring pre-load in the same range you are ~.090.
Since pushrods are "cheap" and relatively easy to swap, I ordered a set of 7.375 pushrods from BTR to bring the pre-load down a bit as an experiment. It was almost immediately quieter and has stayed that way for a few years now. Once the oil heats up it gets a bit louder, but not much. It's still noticeable though, my tuner said that's just how cammed LS1s sound.
Thread Starter
Melting Slicks
Joined: Nov 2011
Posts: 3,164
Likes: 258
From: Virginia
This is just my experience, and yours may vary...
I'm running a BTR stage 2 cam with LS7 lifters and 243's ported and milled just slightly. I started with 7.4" pushrods and the valvetrain was rather loud. I was measuring pre-load in the same range you are ~.090.
Since pushrods are "cheap" and relatively easy to swap, I ordered a set of 7.375 pushrods from BTR to bring the pre-load down a bit as an experiment. It was almost immediately quieter and has stayed that way for a few years now. Once the oil heats up it gets a bit louder, but not much. It's still noticeable though, my tuner said that's just how cammed LS1s sound.
I'm running a BTR stage 2 cam with LS7 lifters and 243's ported and milled just slightly. I started with 7.4" pushrods and the valvetrain was rather loud. I was measuring pre-load in the same range you are ~.090.
Since pushrods are "cheap" and relatively easy to swap, I ordered a set of 7.375 pushrods from BTR to bring the pre-load down a bit as an experiment. It was almost immediately quieter and has stayed that way for a few years now. Once the oil heats up it gets a bit louder, but not much. It's still noticeable though, my tuner said that's just how cammed LS1s sound.
Burning Brakes
Joined: Oct 2014
Posts: 874
Likes: 107
From: Detroit MI
I’ve heard a few other cammed c5’s and none are nearly as loud as mine. You wouldn’t happen to have a video of yours do you? I considered going down a size also and running a lower preload but assumed that would prob create more noise. With the base circle on this cam being smaller than stock I don’t see how I could possibly need a shorter pushrod... I expect noise and I’m ok with that, but I can’t help but think mine could be much quieter.. just sounds like the valvetrain is too loose. I’ve never tried measuring before but I’m going to give it a shot
From what I understand, noise has more to do with the lobe profiles (ramp rates) than anything else...my GUESS is that the lifters like a little extra cushion when dealing with higher ramp rates...at least that's how I explain the results I experienced to myself. I bought the new pushrods for $100 from BTR and sold my 7.4's after for $70...so the experiment really only cost me $30.
Have you taken the valve covers off to check to make sure you don't have any loose rockers? I'd start there...check the rockers to make sure they're all tight. A lose rocker can happen and will cause quite a racket.
Thread Starter
Melting Slicks
Joined: Nov 2011
Posts: 3,164
Likes: 258
From: Virginia
I tried taking a video once, but I only have a phone to record with and it didn't pick up the noise well. Can barely hear it inside the car, but outside with the window down next to another car or a wall, it's noticeable.
From what I understand, noise has more to do with the lobe profiles (ramp rates) than anything else...my GUESS is that the lifters like a little extra cushion when dealing with higher ramp rates...at least that's how I explain the results I experienced to myself. I bought the new pushrods for $100 from BTR and sold my 7.4's after for $70...so the experiment really only cost me $30.
Have you taken the valve covers off to check to make sure you don't have any loose rockers? I'd start there...check the rockers to make sure they're all tight. A lose rocker can happen and will cause quite a racket.
From what I understand, noise has more to do with the lobe profiles (ramp rates) than anything else...my GUESS is that the lifters like a little extra cushion when dealing with higher ramp rates...at least that's how I explain the results I experienced to myself. I bought the new pushrods for $100 from BTR and sold my 7.4's after for $70...so the experiment really only cost me $30.
Have you taken the valve covers off to check to make sure you don't have any loose rockers? I'd start there...check the rockers to make sure they're all tight. A lose rocker can happen and will cause quite a racket.
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Thread Starter
Melting Slicks
Joined: Nov 2011
Posts: 3,164
Likes: 258
From: Virginia
Burning Brakes
Joined: Oct 2016
Posts: 1,205
Likes: 363
From: Massillon Ohio
Thread Starter
Melting Slicks
Joined: Nov 2011
Posts: 3,164
Likes: 258
From: Virginia
Team Owner
Joined: Oct 1999
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From: Guinness Its whats for B'fast JAWGA
CI 3-4-5-9 Veteran
Vettenuts created a few very good topics on here and LS1tech on measuring pushrods and pushrod diameter. 11/32" pushrods are more common now, if you can clear them go 3/8". 243s would have to clearanced for 3/8
Burning Brakes
Joined: Oct 2014
Posts: 874
Likes: 107
From: Detroit MI
Excellent point...I wish I had read those threads BEFORE I purchased my pushrods. 11/32" have gotten much more common these days, and would be worth the purchase if changing length. I'm still at 5/16"...which will be fine for my personal use (99% street car).
Last edited by DetroitPlac; May 14, 2019 at 04:26 PM.
Thread Starter
Melting Slicks
Joined: Nov 2011
Posts: 3,164
Likes: 258
From: Virginia
Here is another quick video after I had the new trunnion kit put in, made no difference. To me it just sounds like there is slop in the valvetrain. So can going up or down a size in pushrods really make that big of a difference in noise? Going from the current 7.400 to either 7.375 or 7.425 could potentially clean up the sewing machine sound? Also I have noticed that it is a bit louder on the drivers side than the pass. I have checked and all rockers are tight.. Btw I am buying a pushrod checker today and going to try and get some measurements myself.
Burning Brakes
Joined: Oct 2014
Posts: 874
Likes: 107
From: Detroit MI
Here is another quick video after I had the new trunnion kit put in, made no difference. To me it just sounds like there is slop in the valvetrain. So can going up or down a size in pushrods really make that big of a difference in noise? Going from the current 7.400 to either 7.375 or 7.425 could potentially clean up the sewing machine sound? Also I have noticed that it is a bit louder on the drivers side than the pass. I have checked and all rockers are tight.. Btw I am buying a pushrod checker today and going to try and get some measurements myself.
https://youtu.be/OoiJEcEbxfU
https://youtu.be/OoiJEcEbxfU
Le Mans Master
Joined: Jul 2010
Posts: 5,987
Likes: 719
What would be the max lifter preload to run on LS7 lifters to be considered safe? The reason I’ asking is because I am currently running 7.400 pushrods with my tsp 228r cam on stock 243 heads and the sewing machine noise is awful. I had a shop measure and I want to say it was a preload of around .085-.090 but I’m not positive. If this is true then would going to a 7.425 be a bad idea? I plan on buying my own adjustable PR tool and checking but I don’t know if mine currently are too long or too short. I believe a higher preload would equal less noise but I didn’t want to be on the red area of excessive wear. Could lowering the preload from what I currently have produce less noise?! If anyone wants a video let me know and I will send one, this is driving me nuts. I have the Straub trunnion upgrade and while it made have quietened overall engine bay motor noise a bit it did not help the sewing machine sound. Just by the sound of my motor holding the rpm’s steady around 2k something has to be off
Last edited by helga203; May 15, 2019 at 10:53 AM.
Thread Starter
Melting Slicks
Joined: Nov 2011
Posts: 3,164
Likes: 258
From: Virginia
Alright so let’s say I measure and I am right at the ideal preload with the 7.400 pr’s, what then?! Where would all that noise be coming from? If it’s simply just loud and not causing any premature wear I guess I will just get over it but surely it could potentially be quieter