Pushrod length sound right?
Thread Starter
10 Second Club
Joined: Jan 2010
Posts: 2,317
Likes: 20
From: Hurley, VA
Pushrod length sound right? Ive got a untouched ls1 short block. I put a 228r in a few monthes ago and just added some PRC 5.3s and new ls7 lifters. When I’m measuring pushrod length I’m coming up with 7.250 to zero lash. Add .050 preload and I’m at 7.300. I’ve measured 5 times. Rolled the motor over I’ve done it with the exhaust valve fully open I’ve done it with both valves shut and I get the same 9 turns. Does this sound right? The heads are milled to 60cc. I was expecting in the 7.375 range not 7.300.
Only caution I would add is it is very easy to slightly depress the lifter cup with new lifters so take care when measuring. You could also back off the pushrod one turn (0.050") and measure the clearance at the rocker than use the rocker ratio to verify your zero lash measurement. This would just be a method of double checking.
Thread Starter
10 Second Club
Joined: Jan 2010
Posts: 2,317
Likes: 20
From: Hurley, VA
What I done was used a bread tie to hold the lower part of the pushrod and turned the upper with my finger until it just touched. The lifters are extremely spongey so I let it just touch. If anything compressing the litter should make the need longer on length. I just don’t understand why they came up so short.
My measurements were around 7.22" on average, Factory LS6 block, Johnson 2110 lifters, stock MLS gaskets, and 317 heads milled .003" for flatness. I was surprised too but I checked more than once and kept getting the same results.
7.3 is not unrealistic. I would go 7.325 to get 075 preload vs 050, but personal preference there.
I am sure you have checked and rechecked, but be doubly sure the rod is in the cup and not up on the rim.
I am sure you have checked and rechecked, but be doubly sure the rod is in the cup and not up on the rim.
If you have a set of check springs and a dial indicator, you can set up one cylinder and actually measure the preload with the pushrod length you are getting (7.300").
The other thing to be careful of is that the lifter is in contact with the cam. If you are rotating the motor while doing this you have to push the lifter down after any lifter movement. There were a few times when I did mine that I actually rotated the motor just to push the lifter up so I could actually hear it contact when I pushed it back down just as insurance I was in contact.
The other thing to be careful of is that the lifter is in contact with the cam. If you are rotating the motor while doing this you have to push the lifter down after any lifter movement. There were a few times when I did mine that I actually rotated the motor just to push the lifter up so I could actually hear it contact when I pushed it back down just as insurance I was in contact.
Trending Topics
Joined: Mar 2007
Posts: 1,145
Likes: 49
From: Saskatchewan, Canada - where arguing "DA" is for the slow and weak...
LS1 Tech Stories
The Best V8 Stories One Small Block at Time
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
Awesome K5 Blazer Restomod Comes With C7 Corvette Power
Verdad Gallardo
10 Camaros You Should Never Buy
10 LS Engine Myths That Refuse to Die
Verdad Gallardo
Thread Starter
10 Second Club
Joined: Jan 2010
Posts: 2,317
Likes: 20
From: Hurley, VA
Head gaskets are GM MLS so from what I remember .051. I ordered some 7.325 so I shot for .075. And Everytime I would measure or rotate the motor I would take a normal pushrod and push down on the lifter. No matter how I did it I would end up within 1/8 of a turn from 7.250 zero lash. I’ve measured 6-8 times.
Teching In
Joined: Jul 2017
Posts: 36
Likes: 1
My 241 heads, 25 thou off, LS7 lifter, MLS gasket, heads torqued down, Ws6 hot cam store, i got 7.375
Use
https://www.ls1.com/forums/f7/how-me...length-172530/
Use
https://www.ls1.com/forums/f7/how-me...length-172530/
