comp r lifters
Team Owner
Joined: Mar 1999
Posts: 22,025
Likes: 192
From: At the beach in little Rhody
I am not using them, but have read enough about them. You need adjustable rockers to get the very tight preload tolerance required. Be warned, there have been many who have had them grenade in the motor and cause major damage. There are a lot of guys over on the LS1Tech board that this has happened to. I went with the Morel's instead.
Former Vendor
Joined: Mar 2004
Posts: 3,442
Likes: 18
From: Winchester CA
i had them before in my old heads/cam motor, and they seemed to work fine but, when i pulled the cam out, i noticed there was some damage on the cam from possibly puking a needle bearing or something
Team Owner
Joined: Mar 1999
Posts: 22,025
Likes: 192
From: At the beach in little Rhody
Not sure which Comp part # you guys are running, but per Comp for the 875-16 lifters:
"Pro Magnum Lifters must be installed with ADJUSTABLE rocker arms and preloaded to 0.002" - 0.004". Always set the preload with the engine warmed to normal operating temperatures to allow for thermal growth."
If you are running the Comp stock replacement lifters, 850-16, this is not required.
"Pro Magnum Lifters must be installed with ADJUSTABLE rocker arms and preloaded to 0.002" - 0.004". Always set the preload with the engine warmed to normal operating temperatures to allow for thermal growth."
If you are running the Comp stock replacement lifters, 850-16, this is not required.
Race Director
Joined: Mar 2001
Posts: 11,405
Likes: 26
From: Whippany NJ
CI 6-7-8-9 Veteran
St. Jude Donor '08-'09
NCM Sinkhole Donor
Originally Posted by Face
You don't need adjustable rockers, I've been running them for 25,000+ miles without any problems.
Ive got 16k miles on my comp Rs with stock rockers and no issues! 
They must be preloaded properly or else it wont work. Thats why I left it to the pros!
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Top 10 Most Expensive Corvettes Ever Sold on Bring A Trailer
Brett Foote
10 Things Every Corvette Owner Needs (2026 Edition)
Michael S. Palmer
8 Most "Only Corvette Owners Understand" Quirks and Problems
Pouria Savadkouei
10 Reasons the C6 Z06 is Still A Performance Benchmark After 20 Years
Joe Kucinski
How Much Horsepower Every Corvette Engine "LOST" in 1972
Joe Kucinski
Top 10 DOs and DON'Ts for Protecting Your Convertible Top!
Michael S. Palmer
Top 10 Most Explosive Corvettes Ever Made: Power-to-Weight Ratio Ranked!
Joe Kucinski
150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter
Joe Kucinski
8 Coolest Corvette Pace Cars (and Replicas) of All Time
Verdad Gallardo
Team Owner
Joined: Mar 1999
Posts: 22,025
Likes: 192
From: At the beach in little Rhody
There is no way you can maintain a 0.002" tolerance on preload with the stock rocker setup. You either have a deeper preload then Comp recommends or you are running the 850's.
Team Owner
Joined: May 2001
Posts: 87,361
Likes: 1,592
From: Western NY
This talk of "grenading" has me a little concerned. I put a set of them in my daily driven Z-28 a couple of years ago (LT-1 engine). They have about 6-7000 miles on them at this point. So far, they've been OK, but I don't rev the snot out of it....
Drifting
Joined: Nov 2005
Posts: 1,406
Likes: 0
From: Dallas Tx
Originally Posted by leadfoot4
This talk of "grenading" has me a little concerned. I put a set of them in my daily driven Z-28 a couple of years ago (LT-1 engine). They have about 6-7000 miles on them at this point. So far, they've been OK, but I don't rev the snot out of it....
Shane
Team Owner
Joined: May 2001
Posts: 87,361
Likes: 1,592
From: Western NY
I just checked in over at LS-1.com. From what I gathered over there, at some point in time, Comp changed the clip that holds the plunger in. My interpretation is that they went from a "C clip to the regular wire clip, and problems ensued...
Team Owner
Joined: Mar 1999
Posts: 22,025
Likes: 192
From: At the beach in little Rhody
I still think that the 850's are being confused with the 875's. Do a quick google on the Comp R's and you will quickly find out that the stock rockers don't get along well with them at all due to the preload. There are numerous posts about this on LS1Tech, and even a lot where they have been correctly setup and still granaded. A lot of the tuners on LS1Tech won't use them anymore because of this.
Thread Starter
Racer
Joined: Jul 2005
Posts: 381
Likes: 0
From: bluff city tn.
well guys i have a set for sale not going to chance it already pulling motor for rod noise what a job without a lift!!! hope to have it out soon not to bad only spent 5 hours so far should be out in about another 1.5 hours are less
Race Director
Joined: Mar 2001
Posts: 11,405
Likes: 26
From: Whippany NJ
CI 6-7-8-9 Veteran
St. Jude Donor '08-'09
NCM Sinkhole Donor
Originally Posted by vettenuts
There is no way you can maintain a 0.002" tolerance on preload with the stock rocker setup. You either have a deeper preload then Comp recommends or you are running the 850's.
http://forums.corvetteforum.com/show...759&forum_id=1
So your going to try to school LG and ECS because they probably installed 850s then huh?
amazing! 
Again, thats why I leave it to the "pros"
Team Owner
Joined: Mar 1999
Posts: 22,025
Likes: 192
From: At the beach in little Rhody
Originally Posted by Ikester
Again, thats why I leave it to the "pros"
As obviously, you should
I don't see anything in post #3 on the lifter preload.
Last edited by vettenuts; Mar 5, 2006 at 08:21 AM.
