I am trying to determine what part number GM is using for the hyd roller lifter in the New 572 motor

This is all the info I have been able to find on the cam and lifters.

"Camshaft Hydraulic roller (Valve lift: .632” I, .632” E; Duration @ .050” 254° I, 264° E)
Lifters Hydraulic roller tappet "

Another question, it has been generally accepted that the stock 502 HO Hyd Roller lifters are only recommended for lifts of up to .550 or .560 lift...Does GMPP have any recommendations on this. I would like to use them on a .590 lift Hyd Roller Marine cam.

Thanks in Advance for any help...

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Originally posted by mc71454:
I am trying to determine what part number GM is using for the hyd roller lifter in the New 572 motor

This is all the info I have been able to find on the cam and lifters.

"Camshaft Hydraulic roller (Valve lift: .632” I, .632” E; Duration @ .050” 254° I, 264° E)
Lifters Hydraulic roller tappet "

Another question, it has been generally accepted that the stock 502 HO Hyd Roller lifters are only recommended for lifts of up to .550 or .560 lift...Does GMPP have any recommendations on this. I would like to use them on a .590 lift Hyd Roller Marine cam.

Thanks in Advance for any help... My best guess would be that it's a Crane cam and lifters, since all of their big hyd. rollers top out at .632 lift. Seems like quite a coincidence.

This is what I know so far...All camshafts have lobes that are just large enough to fit inside the cam bearings. A high lift camshaft will have a smaller bottom (smaller base circle). A very high lift camshaft may drop the lifter down too far into the lifter bore when it is on the bottom of the lobe because it will have a smaller base circle. Lift is the difference between the bottom of the lobe and the top. With such a high lift (small base circle) the stock roller lifter may fall out of the guide bar. A high lift/small base circle camshaft needs taller lifters.

It depends on the amount of lift, or stated another way, how small the base circle has to be made to get a high amount of lift.

A high lift/small base circle camshaft also needs longer push rods to maintain rocker arm geometry.

The issue I have is trying to determine for sure if a hyd roller cam that uses OEM lifters with .544 lift will also be OK using a lift of .590. Both cams have the same base circle, but the bottom of the cam lobe between the face of the lobe and the main shaft of the cam is thinner than the with the lower lift cam.

The lifter will sit 1/32" lower in the lifter bore, which should be fine..

I`m not sure if what you`re concerned with is undue lifter bore wear.
But if it helps we had the lifter bore bosses cut down alot to accomodate the Comp Cams Hyd rollers.
We haven`t experianced any problems so far using a .650 lift cam, street driven and raced, much like your Monte Carlo.
Not sure if this helps at all but I thought I`d offer the thought.

What I am concerned with is the lifter dropping too far into the bore. but it seems it would only be a problem with higher lift cams with a more reduced base circle.

If I remember right, the stock lifters in a 502 are only good to about .570 lift. Anything higher requires the taller by .300 lifters.

With the Chevrolet "dog-bone and spring" retaining system the fear is a smaller base
circle cam will cause the lifters to drop in the
hole, and with severe valve float, could cause the spring to lift allowing the lifters to hang up under the dog-bone retainer.

I know the Crane .300 longer lifters are somewhat
expensive, and would assume the lifters used in the 572 are also Crane units.
Geezer

The difference the lifter will drop between two GM hyd rollers I have is .020".

I measured a .483 lift cam and a .577 lift cam across the cam journals. the .577 cam is on a smaller base circle, but not by much.

I know the lifter is a little over flush with across the dogbone with the .483 lift cam and the dogbone is 0.270" thick.

I will install both of them in a bare block and check out the theory with an actual test.

GM PN 17120061 single Roller Tappet. or PN 12371056 Lifter Kit (16)w/retainer. This is what we use in the ZZ572/620 with hydraulic roller cam @ 0.632 lift.