a98ws6

iTrader: (48)

Building a forged 347 and I am going with a T-rex cam. When is it time to step up from stock lifters to aftermarket? Any recomendations?

davered00ss

iTrader: (4)

Get the Comp factory replacements. Basically when you do heads you should replace them.

a98ws6

iTrader: (48)

Are these the same as the Comp R's?

GuitsBoy

iTrader: (4)

Nope.

Comp OE: 850's
Comp-R: 875's

Although plenty of people are running stock lifter on the Trex. If it were me, id either spring for the morel lifters, or stick with stock (even if you buy new stockers for piece of mind).

Ferocity02

iTrader: (60)

Anyone have the part number for the stock GM lifters? Is it the same part number as the LS7 lifters?

ShevrolayZ28

iTrader: (4)

I decided to use Comp 850s. I installed them today. They were more beefy around the roller area than what came out.

The old ones looked OK as far as wear, but since I was replacing the heads, I thought what the hay.

GuitsBoy

iTrader: (4)

Same lifter.

Wyckedcamaro

iTrader: (2)

i ordered up the comp r hydraulic roller lifters last week.

I had went with an MS4 and just figured.. what the hell?

Ferocity02

iTrader: (60)

Part number?

vettenuts

iTrader: (4)

Based on my "non-scientific" research when the lifter load (max open times rocker ratio) load exceeds 625 lbs, the stock lifters become questionable.

GuitsBoy

iTrader: (4)

Not sure about a specific part number, but all hydraulic roller lifters used in GM v8 1987 through current are suposedly the same part. Furthemore with the exception of morel and comp, all GM and other branded lifters are made my one of two companies, Delphi and Eaton. IIRC, GM used the eaton style in the ls1 until 2000. From 2001 they used the delphi style. I prefer the earlier fully encapsulated eaton style. You can save yourself somecash by ordering either the summit branded hydraulic roller lifters, or you can order some melling lifters. I went with the melling lifters and theyre certainly the encapsulated eaton type. Allan futral even uses the inexpensive mellings in his big stroker motors, so they certainly hold up well.

TheBlurLS1

iTrader: (8)

I believe you need adjustable rockers to run the R's, just a heads up.

ShevrolayZ28

iTrader: (4)

LSx lifter = 17122490

https://ls1tech.com/forums/showpost....5&postcount=13

FWIW, Comp does recommend that adjustable rockers be used with the R's.