Trouble with pushrod length checking - please help
Trouble with pushrod length checking - please help Hello,
I have a junkyard gen III 5.3L LM4 with 100k miles that I just picked up. I swapped the stock cam and springs with an 01 z06 cam and springs. New lifter trays. Also pulled the heads off, gapped the rings and put in MLS head gaskets. Reused the stock lifters. I dropped each lifter into a bucket of clean oil and shook them for a few seconds before installing.
Now I am checking pushrod length. I watched the Holdener video on checking pushrod length.
https://youtu.be/JpbuI4xqgyo?si=vpg6oPvwKSCwpzOJ
I have never done this before. I noticed that one lifter I can obviously compress by hand by pushing my thumb on top of the pushrod. All of the others feel rock hard and I can't compress by hand. Which one is normal?
When doing the 'turns' method on the compressible lifter, I get a length longer than expected. I get between 1.25- 1.375 turns with 7.575 on the length checker.
When I do it on the 'hard' lifters, after I set the rocker to zero lash, and I am turning the rocker bolt, it seems to just compress the spring and takes a large amount of turns. For example, when I do this with the adjustable pushrod at the same 7.575, it takes 3.25 turns. But it's obvious that the lifter isn't compressing and just the spring is.
Not sure what to make of this. Opinions?
Thanks
I have a junkyard gen III 5.3L LM4 with 100k miles that I just picked up. I swapped the stock cam and springs with an 01 z06 cam and springs. New lifter trays. Also pulled the heads off, gapped the rings and put in MLS head gaskets. Reused the stock lifters. I dropped each lifter into a bucket of clean oil and shook them for a few seconds before installing.
Now I am checking pushrod length. I watched the Holdener video on checking pushrod length.
https://youtu.be/JpbuI4xqgyo?si=vpg6oPvwKSCwpzOJ
I have never done this before. I noticed that one lifter I can obviously compress by hand by pushing my thumb on top of the pushrod. All of the others feel rock hard and I can't compress by hand. Which one is normal?
When doing the 'turns' method on the compressible lifter, I get a length longer than expected. I get between 1.25- 1.375 turns with 7.575 on the length checker.
When I do it on the 'hard' lifters, after I set the rocker to zero lash, and I am turning the rocker bolt, it seems to just compress the spring and takes a large amount of turns. For example, when I do this with the adjustable pushrod at the same 7.575, it takes 3.25 turns. But it's obvious that the lifter isn't compressing and just the spring is.
Not sure what to make of this. Opinions?
Thanks
Last edited by fusion_ta66; Sep 3, 2023 at 08:34 AM.
Staging Lane
Joined: May 2023
Posts: 90
Likes: 71
Hello,
I have a junkyard gen III 5.3L LM4 with 100k miles that I just picked up. I swapped the stock cam and springs with an 01 z06 cam and springs. New lifter trays. Also pulled the heads off, gapped the rings and put in MLS head gaskets. Reused the stock lifters. I dropped each lifter into a bucket of clean oil and shook them for a few seconds before installing.
Now I am checking pushrod length. I watched the Holdener video on checking pushrod length.
https://youtu.be/JpbuI4xqgyo?si=vpg6oPvwKSCwpzOJ
I have never done this before. I noticed that one lifter I can obviously compress by hand by pushing my thumb on top of the pushrod. All of the others feel rock hard and I can't compress by hand. Which one is normal?
When doing the 'turns' method on the compressible lifter, I think it works as expected. I get between 1.25- 1.375 turns with 7.575 on the length checker. So the length I need would be 7.575. Does that sound like the right length for this setup?
When I do it on the 'hard' lifters, after I set the rocker to zero lash, and I am turning the rocker bolt, it seems to just compress the spring and takes a large amount of turns. For example, when I do this with the adjustable pushrod at the same 7.575, it takes 3.25 turns. But it's obvious that the lifter isn't compressing and just the spring is.
Not sure what to make of this. Opinions?
Thanks
I have a junkyard gen III 5.3L LM4 with 100k miles that I just picked up. I swapped the stock cam and springs with an 01 z06 cam and springs. New lifter trays. Also pulled the heads off, gapped the rings and put in MLS head gaskets. Reused the stock lifters. I dropped each lifter into a bucket of clean oil and shook them for a few seconds before installing.
Now I am checking pushrod length. I watched the Holdener video on checking pushrod length.
https://youtu.be/JpbuI4xqgyo?si=vpg6oPvwKSCwpzOJ
I have never done this before. I noticed that one lifter I can obviously compress by hand by pushing my thumb on top of the pushrod. All of the others feel rock hard and I can't compress by hand. Which one is normal?
When doing the 'turns' method on the compressible lifter, I think it works as expected. I get between 1.25- 1.375 turns with 7.575 on the length checker. So the length I need would be 7.575. Does that sound like the right length for this setup?
When I do it on the 'hard' lifters, after I set the rocker to zero lash, and I am turning the rocker bolt, it seems to just compress the spring and takes a large amount of turns. For example, when I do this with the adjustable pushrod at the same 7.575, it takes 3.25 turns. But it's obvious that the lifter isn't compressing and just the spring is.
Not sure what to make of this. Opinions?
Thanks
After more research it looks like most people that run the LS6 z06 cam in a 5.3 use either stock 7.400 pushrods or 7.425 pushrods. So I'm not really sure why I'm getting different numbers. I will try again with a different method
At this point my main concern is the lifters. I am wondering if I should have done something different before I installed them. I thought fully submerging them in fresh oil was sufficient. I'm guessing that the one lifter that I can compress has air in it. But should all the other lifters be basically incompressible?
The thought has crossed my mind that perhaps the lifters are bad, but 15 of them? The boneyard said it ran great.
Feeling a little sick about this as I just bolted on the heads. Looking for some guidance, please.
At this point my main concern is the lifters. I am wondering if I should have done something different before I installed them. I thought fully submerging them in fresh oil was sufficient. I'm guessing that the one lifter that I can compress has air in it. But should all the other lifters be basically incompressible?
The thought has crossed my mind that perhaps the lifters are bad, but 15 of them? The boneyard said it ran great.
Feeling a little sick about this as I just bolted on the heads. Looking for some guidance, please.
TECH Fanatic
Joined: Jan 2009
Posts: 1,063
Likes: 475
From: Bostwick, GA.
"When doing the 'turns' method on the compressible lifter, I think it works as expected. I get between 1.25- 1.375 turns with 7.575 on the length checker. So the length I need would be 7.575. Does that sound like the right length for this setup?"
Absolutely not. You are starting out with a checking length .135 longer than stock.
Adding in 1.3/8th turns just pushes the lifter cup into the bottom of the lifter.
As mentioned, use the checker at stock length to begin with.
Absolutely not. You are starting out with a checking length .135 longer than stock.
Adding in 1.3/8th turns just pushes the lifter cup into the bottom of the lifter.
As mentioned, use the checker at stock length to begin with.
"When doing the 'turns' method on the compressible lifter, I think it works as expected. I get between 1.25- 1.375 turns with 7.575 on the length checker. So the length I need would be 7.575. Does that sound like the right length for this setup?"
Absolutely not. You are starting out with a checking length .135 longer than stock.
Adding in 1.3/8th turns just pushes the lifter cup into the bottom of the lifter.
As mentioned, use the checker at stock length to begin with.
Absolutely not. You are starting out with a checking length .135 longer than stock.
Adding in 1.3/8th turns just pushes the lifter cup into the bottom of the lifter.
As mentioned, use the checker at stock length to begin with.
Last edited by grinder11; Sep 7, 2023 at 03:27 PM.
Thanks everyone. For clarity, I didn't start at 7.575. I started with 7.300. that resulted in the rocker bottoming out before I even got to zero lash. I then kept increasing the pushrod checker until I got into the appropriate turns range as shown in the video.
When I checked length with the zero lash method and add in appropriate preload, I do get 7.400-7.450 length and that seems right.
But, I was hoping for opinions on my lifters. Is what I am seeing normal? I'm assuming that once I fire the engine and it runs for a few seconds, all the lifters will be 'unstuck' and not be so rock hard. Because now when I do the 'turns' method as highlighted in the Holdener video, any turns past zero lash just compress the spring.
Otherwise I'll have to take the heads back off and possibly get new lifters, which obviously isn't ideal.
Thanks again
When I checked length with the zero lash method and add in appropriate preload, I do get 7.400-7.450 length and that seems right.
But, I was hoping for opinions on my lifters. Is what I am seeing normal? I'm assuming that once I fire the engine and it runs for a few seconds, all the lifters will be 'unstuck' and not be so rock hard. Because now when I do the 'turns' method as highlighted in the Holdener video, any turns past zero lash just compress the spring.
Otherwise I'll have to take the heads back off and possibly get new lifters, which obviously isn't ideal.
Thanks again
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TECH Addict
Joined: Dec 2017
Posts: 2,180
Likes: 969
Happens when one gets to the octogenarian era!
The CORRECT way to use the adjustable push rod is to lengthen it until it JUST BARELY takes up all the SLACK in the valve train. At that point in the process, doesn't matter how far the lifter plunger depresses, how easy it is to depress, or ANYTHING ELSE about the lifter plunger. It's supposed to be all the way up against the retaining ring. Adjust it to THAT POINT and NO FURTHER. Check its length. THEN AND ONLY THEN, add your desired preload to that measurement, and order.
7.400 - 7.450" sounds much more believable.
What will actually happen with the lifters once the engine is running is, they will ALL get "rock hard", at the height that the push rods hold them at. The one(s) that aren't "hard" now merely have no oil in their little chamber. They'll get "hard" once oil gets pumped into them.
Take it from someone whose lifter doesn't need any little blue pills in spite of all the centuries.
TECH Fanatic
Joined: Jan 2009
Posts: 1,063
Likes: 475
From: Bostwick, GA.
"Take it from someone whose lifter doesn't need any little blue pills in spite of all the centuries."
Me either!
My problem is excessive "torque rise".
Bend it down, and it jacks your heels off the floor.
Me either!
My problem is excessive "torque rise".
Bend it down, and it jacks your heels off the floor.
12 Second Club
Joined: Oct 2003
Posts: 146
Likes: 11
From: Mpls. Mn.
I abandoned the turns method for checking length, the only way to do it in my opinion is with an adjustable checker and a set of calipers, neither of which are terribly expensive. I would also buy new, quality lifters; they are also not cripplingy expensive in most cases. You don't want to have to tear into it again to replace a used lifter. Ask me how I know!!
I abandoned the turns method for checking length, the only way to do it in my opinion is with an adjustable checker and a set of calipers, neither of which are terribly expensive. I would also buy new, quality lifters; they are also not cripplingy expensive in most cases. You don't want to have to tear into it again to replace a used lifter. Ask me how I know!!
Launching!
Joined: Feb 2018
Posts: 224
Likes: 31
From: Bismarck, ND
Base circle Hello,
I have a junkyard gen III 5.3L LM4 with 100k miles that I just picked up. I swapped the stock cam and springs with an 01 z06 cam and springs. New lifter trays. Also pulled the heads off, gapped the rings and put in MLS head gaskets. Reused the stock lifters. I dropped each lifter into a bucket of clean oil and shook them for a few seconds before installing.
Now I am checking pushrod length. I watched the Holdener video on checking pushrod length.
https://youtu.be/JpbuI4xqgyo?si=vpg6oPvwKSCwpzOJ
I have never done this before. I noticed that one lifter I can obviously compress by hand by pushing my thumb on top of the pushrod. All of the others feel rock hard and I can't compress by hand. Which one is normal?
When doing the 'turns' method on the compressible lifter, I get a length longer than expected. I get between 1.25- 1.375 turns with 7.575 on the length checker.
When I do it on the 'hard' lifters, after I set the rocker to zero lash, and I am turning the rocker bolt, it seems to just compress the spring and takes a large amount of turns. For example, when I do this with the adjustable pushrod at the same 7.575, it takes 3.25 turns. But it's obvious that the lifter isn't compressing and just the spring is.
Not sure what to make of this. Opinions?
Thanks
I have a junkyard gen III 5.3L LM4 with 100k miles that I just picked up. I swapped the stock cam and springs with an 01 z06 cam and springs. New lifter trays. Also pulled the heads off, gapped the rings and put in MLS head gaskets. Reused the stock lifters. I dropped each lifter into a bucket of clean oil and shook them for a few seconds before installing.
Now I am checking pushrod length. I watched the Holdener video on checking pushrod length.
https://youtu.be/JpbuI4xqgyo?si=vpg6oPvwKSCwpzOJ
I have never done this before. I noticed that one lifter I can obviously compress by hand by pushing my thumb on top of the pushrod. All of the others feel rock hard and I can't compress by hand. Which one is normal?
When doing the 'turns' method on the compressible lifter, I get a length longer than expected. I get between 1.25- 1.375 turns with 7.575 on the length checker.
When I do it on the 'hard' lifters, after I set the rocker to zero lash, and I am turning the rocker bolt, it seems to just compress the spring and takes a large amount of turns. For example, when I do this with the adjustable pushrod at the same 7.575, it takes 3.25 turns. But it's obvious that the lifter isn't compressing and just the spring is.
Not sure what to make of this. Opinions?
Thanks