dgsmith

If already posted, I apologize. Anyway, does any know what the original GM part number was for the Duntov (097) "high lift" cam. It was first used in Jan. '56 (I think) in the 265. Thanks.

JohnZ

The PART number for the "097" Duntov cam was 3736097, and the raised casting number on the cam was 3736098. It was used from 1957-1963. The high-lift cam used only in 111 units in 1956 (the "240hp cam") was P/N 3734077.

dgsmith

Thankyou John

mhorst57

John - This thread is quite old, but I am trying to learn more about the 1956 high-lift cam mentioned in your response. If you receive this, can you provide additional insight.

I recently purchased a1956 Corvette, originally sold by my grandfathers dealership. The original build sheet and sales invoice note the 449 option for the high-lift cam. Is there any known resource to understand how many of the 111 are around?

Thanks - Mike

SWCDuke

The '55-'56 small blocks have a slightly different oiling system. These early engines needed a "notch" or "divot" in the rear cam bearing. It's somewhat analogous to the early big block situation.

The depressions were different for mechanical and hydraulic lifter cams. That's why I called them notch/divot, but don't recall which was used for the different cam types, mechanical or hydraulic lifter.

The interesting thing about this system based on my analysis of the design is that lifter gallery oiling was intermittent, not continuous.

In any event, the design was changed for '57-up with an machined annular groove in the block rear cam bearing support that provided full time oiling to the lifter galleries.

That's why the '56 Duntov cam has a different part number. It has the oiling provision in the rear journal, but the lobes are identical to the ...097 version that was used from '57 to '63 that has a plain, round rear journal without the notch or divot that was required on the '55-'56 camshafts.

Duke

Critter1

In the late 50's, a friends Mother had a 55 Chev with a 265" engine and at a slow idle, the oil light would flash about every other crankshaft revolution. (once for every cam revolution). I assumed it was because of that notched cam.

MikeM

I "think" I remember the hydraulic cams used the large notch and the solid lifter engines used the small notch. The last Duntov I put in my '56 Bel Air was a used, 315 hp cam. It didn't have the notch as it was for a later 283. Anyway, I slapped the rear journal against a grinding wheel. and cut a notch in it. I think I cut the notch too big as that sucker would spit oil across the fender while adjusting the valves.

SWCDuke

Weren't all '55 small block mechanical lifter cams?

Duke

Critter1

I'll have to look in a few books, Duke. That's a little before my time.

MikeM

The very first manual transmission engines were solid lifter, later changed to hydraulic. Or maybe solids all year. Don't remember.

All the PG engines were hydraulic.

Critter1

Here's what a 1963 printing of the GM parts book shows. (word for word) One description doesn't agree with the other.

55-56 Pass, Corvette (8 cyl) mechanical type (two piece body-hole in body-2 grooves)...........5231315.

55-61 All, Corvette (8 cyl) (exc H.L Cam, H/Perf., Sp. H/Per) Hydraulic type................................3799 644.

The descriptions are a bit vague but it sounds like all 55-56's with H.L. cam used mechanical lifters but all others had hydraulics.

Robert61

The ones I've seen were notched for a solid lifter and a groove all of the way around the rear journal for a hydraulic. They may well have all been aftermarket.



I looked at some pics of the o.e. stuff. The solid had the small notch the hydraulic had the much deeper notch. If I were building one today I would just grind the notch between the passages and run a regular type cam.

MikeM

Chevrolet used three different solid lifter V-8 camshafts in '55-'56. Not all limited to Corvette.

162/180 hp standard shift pass car engine

195/210/225 hp Corvette engine (225 pass car included)

240 hp Pass car/Corvette engine

That was the three solid camshafts.

The 1955 pass car six cylinder with standard shift used a solid lifter cam while the PG used hydraulic.

Critter1

Not a good shot of a 63 parts book but it doesn't completely agree with what you posted. I'll get a better pic later.

Also, I thought only the 216 pass car as late as 1953 had solids while the 235 had hyd. Looks like that was only until 1953.

MikeM

I've been to the eye doctor and have drops in my eyes. Can't read your pictures, yet. I did open up a '61 parts book and unless I missed something....................

It shows a listing for hydraulic valve lifters for a 265 PG engine. No mention of standard shift but it does list mechanical lifters for '55 pass car engines. Since the "small" 195 hp cam wasn't available in pass car engines, one might assume these lifters went in a manual shift '55 265.

The only solid lifter listing for '55 six cylinder is Corvette. Shows hydraulic lifters specifically for '55 PG pass car.

On camshafts.................

Specifically lists '55 265 pass car solid lifter cam 3836700 which was the standard 162 hp issue pass car cam

Lists slid lifter cam 3711354 which was used in 210/225 Corvette '55-'56 engines and '56 225 pass car.

The 1956 version of the 097 is listed as well. 3734077. That would be the third unique solid lifter 265 cam.


Camshafts for '54-'55 six cylinder pass car, standard shift lists the same cam as trucks which were all mechanical lifter as ID'd in the lifter group. The '55 PG engine cam has a different part number.

One last thing. The 265 valve lifters were different than the 283 type with the different oiling system. Maybe that's why when I changed cams and used 283 lifters, it shot oil across the fenders when adjusting valves?

I have a '55 service manual here somewhere. If I find it and it post other information, I'll post it here just for info.

PAmotorman

wide groove for hyd lifters narrow groove for mech lifters. all 55 were mech lifers. 56 std shift mech lifters and powerglide engines had hyd lifters

MikeM

As previously stated, you're correct on the oiling notches.

Your memory has failed you on the mech vs hydrauic lifter usage. See previous post.