GM solid lifter confusion

[Steve Antonucci]

Hi all!

I have a question pertaining to GM solid lifters. From time to time, I run
accross NOS GM solid lifters. Recently, I learned that there are two ( at
least two ) versions of the GM solid lifter: 5231585 & 5232695

One is evidently for standard ball-seat rockers and the other is possibly for
roller-type rocker applications. The latter evidently allows less oil to the
top end of the engine ( rocker arm assembly ). So here is the question:

If I build an L/71 or L-88 and I want to use roller rockers, can I use either
lifter, or are there hidden problems to be aware of?

Thanks,
Steve

[Clem Z.]

yes either type with roller rockers but

you will have abour 20/25% more oil upstairs with 695s. a lot of SBC were built by GM with 585s and ran for years with no problems because of the valve springs were not very heavy.

[Duke W.]

Re: GM solid lifter confusion

The 585s were OE on all SB'w with mechanical lifter cams and 695s were OE on all big block mechanical lifter engiens; 585s would probably be okay on a BB with full roller rockers, but they or their aftermarket equivalent are tough in not impossible to find.

Duke

[Steve Antonucci]

Re: GM solid lifter confusion

Duke,

I have heard it said that the GM lifters are "better" than the aftermarket
versions available today. This seems to defy logic. The base of the lifter
is a simple hemispherical cross-section if I understand this correctly. That
being said, how badly can one manufacturer make them? I guess stated another
way, are the GM lifters worth the trouble? I know our friend Joe Lucia has
a few or more GM sets he's keeping for that rainy day.....

Steve

[Joe L.]

Re: GM solid lifter confusion

Steve-----

Personally, I like GM lifters better than all others. But, that's a personal preference. I think that all of the lifters of major brands on the market today are fine. There are really only a few companies that actually manufacture flat tappet lifters. DELPHI (GM spin-off comapany that makes the GM/Delco lifters) is one of those companies. If you use an aftermarket reproduction cam (like a Crane reproduction of an original GM cam) you must use the cam manufacturer-supplied lifters or lose the warranty (if that's important to you).

The GM #5231585 was an edge-orifice type lifter. This lifter (and predecessor part number) was used on most small blocks with mechanical lifter cams from 1957 through 1972. The exception was 67-69 Z-28 Camaro 302 cid engines.

The GM #5232695 is a "piddle valve" type lifter. It allows more oil to pass to the valve train than does the edge orifice type. It was used for all 65-71 big blocks with mechanical lifter cams and also 67-69 Z-28.

Either of the above lifters could be used with a big block with roller rocker arms; only the 5232695 should be used with conventional rockers.

Both GM mechanical lifters are discontinued. Both are difficult to find. As Duke mentioned, the edge-orifice type are generally not available in the aftermarket anymore. Therefore, the piddle valve type must be used. This is the type supplied in most cam kits and by aftermarket cam manufacturers.

Yes, I have PLENTY of both types, especially the 5232695. I've got these "coming out my ears" [none for sale]. So, why does a guy that's become a "roller lifter guy" have all these mechanical flat tappet lifters around? That's a VERY good question.

[Duke W.]

Re: GM solid lifter confusion

There are a lot of mechanical lifter stories floating around, and they seem to be in short supply.

According to some stories, only ONE company is left that produces vintage mechanical lifters and they are the ...695 piddle valve type.

If GM does actually still supply them, I doubt if GM actually manufactured them.

If the "one source" story is true, then just by on price.

FM Speed Pro lists the ...585 edge orifice type as "racing lifters" under part number AT840R, but I don't know if they are still available.

One advantage of the lower flowing edge orifice type is that with less oil flowing to the rocker boxes there is less chance that a restricted wet sump system can be sucked dry during sustained high rev operation. High sustained revs make it tough for the oil to get back to the pan. That's why racers up to the early seventies (about the time SCCA allowed dry sumps on production-class cars) overfilled the pans by a quart or more.

Duke

Duke

[Steve Antonucci]

Re: GM solid lifter confusion

Joe,

Regarding lifter: 5231585, why was this not used on the Z/28's? What set the
302 apart from the SHP Vette engines? The high rev capability of the 302?

For an L-88 or L/71 application, will I suffer any ills by pumping extra oil
up to the rockers ( roller type ) by using lifter: 5232695? Some suggested
that this robs power due to oil drag through drain-back to the pan. I find
that somewhat hard to believe. What do you think?

Lastly, can I bug you to post images of both lifters in question. I'd like
to see the differences ( assuming there are some physical differences )? If
you can't post the images, I can if you send them to me.

To address your comments about the GM SHP lifter rarity, I can tell you that I
saw a "slightly used" set of SHP lifters go for several hundred dollars
recently on the ever amazing eBay. I can't imagine why so many bidders would
go after used lifters. Are they hopeful the lifters will work ( re-wear properly ), or foolish?

Steve

[Clem Z.]

my new 66 450HP 427 corvette

would have the oil pressure start to fall off at the end of the drag strip because the oil could not get back down to the pan fast enought. i would 1 quart over full at the strip. on all my race track engine i used the edge orifice lifters even with a racing oil pan. the difference is in the location of the oil hole in the side of the lifter,edge orifice ones have the hole above the center recess and the piddle valve ones have the oil hole in the recess and they also rattle when you shake them

[Joe L.]

Re: GM solid lifter confusion

Duke-----

GM does not make too many things, at all, anymore since they spun off DELPHI several years ago. However, the AC Spark Plug Division (or whatever they call it now) of DELPHI does make both hydraulic flat tappet and hydraulic roller lifters. They do not manufacture mechanical-type lifters anymore, though. Both of the lifters discussed here have been discontinued by GM for quite some time.

There are at least 2 other companies that manufacture flat tappet lifters. Hylift is one of these companies. In the last few years, they also aqcquired the assets of Johnson Lifter Company, which was the old-line company that went bankrupt several years ago and threw the automotive rpelacement parts industry into a severe lifter shortage. I believe that there is also at least one other company, but I've forgotten the name of it.

As far as mechanical type lifters go, I doubt that there is currently more than one manufacturing source. I know it's not DELPHI. So, which one of the others it is, I do not know. The current market for these has to be so low that I don't see how more than one manufacturer could be supported.

[Joe L.]

Re: GM solid lifter confusion

Steve-----

I don't know why that the 5232695 was used on Z-28's. I presume that someone at GM felt that they needed more oil to the valve train. That's the only reason that the 5232695 lifter would have been used over the usual small block mechanical lifter.

I don't think that any problem will be created by using the 5232695 lifters with roller rocker arms. You'll be getting more oil to the upper valve train than you need, but it will be exactly the same amount as would get there in most other big blocks. Using a resticted amount to the valvetrain might represent an ADVANTAGE, but using the stock oil flow will not create any disadvantage.

Digging out those lifters right now is not high on my list of things to do. However, as clem mentioned, the 2 different types are very easy to tell apart. The edge orifice lifters have the oil hole in the side of the lifter body in the machined surface which contacts the lifter bores in the block. The piddle valve lifters have the hole in the wide, shallow groove in the center of the lifter body. They can be told apart at a glance.

Some folks might pay Big $$$$ for used lifters. One of those folks is not me. Regardless of how little used, I would not even pay $1 for a complete engine set of used lifters (unless I wanted the lifters for some reference purpose but NEVER to use in an engine).

[Michael H.]

Re: GM solid lifter confusion

Steve,

In 1967-69, the SCCA rules for Trans-Am cars stated that no aftermarket roller rocker arms were allowed. The stock stamped steel arm was the only thing Chevrolet had to offer and with the much increased pressure of the optional "142" heavy duty GM valve spring, the rocker arms required additional lubrication to survive.

Another point that many miss, or ignore, is the fact that valve springs need a constant flow of cooling oil. This is especially true for the exhaust valve spring. When these things are cycled at high speed, they generate a lot of heat. Spring failure is often high in engines that have the upper oiling system metered or reduced. Drag race engines would obviously not be affected as they only run for brief periods but consider the life of a Trans-Am engine.

[Clem Z.]

valve spring life depends on oil in race

engines that is why spring oilers built into the rocker covers are used on them. these spray oil directly onto the valve springs. when GM went to the indy 500 with some stock block engine the found the valve springs on one side of the engine would go away in just one high speed lap. it was centrifugal force that was keeping the oil off of the springs in the turns. a test at GM showed that less than 30 seconds without oil the exhaust valve springs would turn cherry red. before spring oilers we used a stand pipe in the oil return holes in the heads to keep the bottom of the valve springs in oil to cool them

[Steve Antonucci]

Re: GM solid lifter confusion

Michael,

That is an interesting perspective on top end oiling. You tend to think
about the moving parts when oil is mentioned, but not springs. I have
seen many times where BBC spring failure lead to engine demise due to
dropped valve(s). Never a pretty sight! Especially when we spend tons
of $$ on restoration engines. For that reason alone, I had been warned
to stay away from NOS GM valve springs in a restoration of an L/71 or L-88.

I'd sure like to hear more from others on this board about this?

Thanks again,

Steve

[Steve Antonucci]

Re: valve spring life depends on oil in race

Clem,

Did this need for top end oil have anything to do with the addition of
drippers to BBC valve covers? Yet, teh Z/28's didn't have drippers.

Cherry red in 30 seconds - huh? Sounds like a good movie title !!!!

Steve

[Michael H.]

Re: GM solid lifter confusion

Steve,

Yes, this subject seems to get swept under the rug most of the time but it really is important that the springs get the cooling they need from oil flow. I always chuckle when garage engineers decide they can out smart the guys in engineering that made these discoveries decades ago. If I remember correctly, this was the very reason the first design lifters in 65-66 big blocks were changed to a different part number/design. More overhead oil was needed to help cure the valve spring failure problem. (it didn't help, obviously) I'm sure others will add to this story.

I agree, the entire valve train on ANY 65-69 big block should be trashed and replaced with all new current GM parts. The valves are the only thing worth saving.

Some time in 1969, the Z28 cast aluminum valve covers were redesigned to include drippers. This was not only for the lubrication of the valve end of the rocker arm but also to increase oil flow over the valve springs.