Another pushrod length question.
Thread Starter
On The Tree
Joined: Nov 2021
Posts: 138
Likes: 15
Another pushrod length question. So I’m changing pushrods after putting smaller head gaskets and milled heads. I ran the 7.4s with these heads before I swapped gaskets but I suspected them to be too long back then. Ran ok though just sounded like it didn’t have compression when I shut it off before. Didn’t turn off immediately almost like dieseling. Anyway I used the adjustable pushrod had the rocker torqued was at zero lash got 7.24400 on the adjustable pr plus the .090 preload for ls7 lifters it comes close to the 7.35 pushrod. I measured the adjustable pr to 7.35 and tighten the rocker down with a nut runner screwdriver then tighten it with a ratchet it fully seated at about 1 1/4 turn to 1 1/2 turn but it looks like it’s pushing the spring down still. Should this be happening? When I loosened it and did it again it tightened all the way at like a 1/4 turn so it must have pushed the oil out of the lifter. Every cylinder I measure comes close to the 7.35 pr I’m just rounding to it. I can post the exact measurements I’ll go do it again on another cylinder
TECH Fanatic
Joined: Jan 2018
Posts: 1,250
Likes: 239
From: Dade City, Fl.
If it is, the lifter could be pumped up and holding oil pressure which could be opening the valve slightly. If it is only depressing a couple of thousandth of a inch it's probably an ok length push rod
Thread Starter
On The Tree
Joined: Nov 2021
Posts: 138
Likes: 15
1 full turn to seat the rocker is too short of a pushrod right? Isn’t it 1 1/4 or 1 1/2 turns for correct length
Do not count the turns of the bolt. Take a set of calipers, follow EOIC (Exhaust Opening Intake Closing). So when you measure an intake rod, you will turn the motor over until the Exhaust rod is opening the valve (coming up from the lifter).
Get the pushrod tool close (tape the threads so it can't turn too easily) and install it. Tighten the rocker bolt down just snug. The rocker just needs to be sat in the pedestal. Not torqued.
Check for lash, and adjust the pushrod tool out until there is no lash left. Measure the pushrod tool end to end, and then add your preload amount to that.
Follow this video from Brian at Summit. This is the proper way to do this.
Get the pushrod tool close (tape the threads so it can't turn too easily) and install it. Tighten the rocker bolt down just snug. The rocker just needs to be sat in the pedestal. Not torqued.
Check for lash, and adjust the pushrod tool out until there is no lash left. Measure the pushrod tool end to end, and then add your preload amount to that.
Follow this video from Brian at Summit. This is the proper way to do this.
Trending Topics
Thread Starter
On The Tree
Joined: Nov 2021
Posts: 138
Likes: 15
Do not count the turns of the bolt. Take a set of calipers, follow EOIC (Exhaust Opening Intake Closing). So when you measure an intake rod, you will turn the motor over until the Exhaust rod is opening the valve (coming up from the lifter).
Get the pushrod tool close (tape the threads so it can't turn too easily) and install it. Tighten the rocker bolt down just snug. The rocker just needs to be sat in the pedestal. Not torqued.
Check for lash, and adjust the pushrod tool out until there is no lash left. Measure the pushrod tool end to end, and then add your preload amount to that.
Follow this video from Brian at Summit. This is the proper way to do this.
https://www.youtube.com/watch?v=H00Vannrt-c&t=2s
Get the pushrod tool close (tape the threads so it can't turn too easily) and install it. Tighten the rocker bolt down just snug. The rocker just needs to be sat in the pedestal. Not torqued.
Check for lash, and adjust the pushrod tool out until there is no lash left. Measure the pushrod tool end to end, and then add your preload amount to that.
Follow this video from Brian at Summit. This is the proper way to do this.
https://www.youtube.com/watch?v=H00Vannrt-c&t=2s
LS1 Tech Stories
The Best V8 Stories One Small Block at Time
Gas Monkey Built a 6-Wheel Ferrari Testarossa With a Corvette LT4 Engine
Verdad Gallardo
7 Most Reliable High-Performance Engines GM Has Ever Built
Verdad Gallardo
Amazing '71 Camaro Restomod Is Modern Muscle Car Under the Skin
Verdad Gallardo
6 Common C5 Corvette Failures and What's Involved In Repairing Them
Pouria Savadkouei
Retro Modern Bandit Pontiac Trans AM Comes With Burt Reynolds' Autograph
Verdad Gallardo
Top 10 Greatest Cadillac V Series Performance Models Ever, Ranked
Pouria Savadkouei
Top 10 Most Powerful Chevy Trucks Ever Made!
Hennessey's New Supercharged Silverado ZR2 Has 700 HP
Verdad Gallardo
Coachbuilt N2A Anteros Is an LS2-Powered C6 Corvette In Italian Clothes
Verdad Gallardo
Unfortunately that's about the only way to do it. Basically trial and error until you have the right length and once you've found it then check some other lobes to be certain that you have the correct length at zero.
Thread Starter
On The Tree
Joined: Nov 2021
Posts: 138
Likes: 15
I keep getting different numbers on each one but still seems to be close to 7.35 when I add .090 preload. Some go above 7.35 then I add .085 it’s still right about 7.35. What is the ls7 lifter preload range again .060-.100 right
TECH Fanatic
Joined: Jan 2018
Posts: 1,250
Likes: 239
From: Dade City, Fl.
Yeah I'd shoot for someting around .080-.090 on preload so it sounds to me like you're there. Techinically, this should be done with some homemade solid LS7 lifters because it would be difficult to get an exact measurement everytime when working with hydraulic lifters so it wouldn't surpirse me if you were getting differences but not enough to matter when you have such a large range of preload. Keep measuring until you're confident that you've determined the length that puts you where you want to be.
It's likely you ARE getting slightly different readings on each one. Some might be .005"-.010" different than the next, and so on....
Thread Starter
On The Tree
Joined: Nov 2021
Posts: 138
Likes: 15
Yeah I'd shoot for someting around .080-.090 on preload so it sounds to me like you're there. Techinically, this should be done with some homemade solid LS7 lifters because it would be difficult to get an exact measurement everytime when working with hydraulic lifters so it wouldn't surpirse me if you were getting differences but not enough to matter when you have such a large range of preload. Keep measuring until you're confident that you've determined the length that puts you where you want to be.
Thread Starter
On The Tree
Joined: Nov 2021
Posts: 138
Likes: 15