Engine and Transmission Tech

Oldsmobile 215 engine.....I bought this from a machine shop in Kansas with the intention of using it in my MGB. I was told the engine has been completely rebuilt, the compression test has 100 psi in all cylinders.



Edited 1 time(s). Last edit at 10/07/2015 08:47PM by MGBV8.

That's a poor compression number. For a fresh rebuild on an Olds 215 that would signify the use of low compression Buick pistons with the 2bbl Olds heads, resulting in a CR of about 6-1/2:1, and it'll run that way, I had one that I used for years as a spare or "mule" engine whenever the good motor was down for repairs. Figure on around 135 HP and poor fuel mileage. Unless you misstated the compression figure.

Jim

These are numbers I was told from the machine shop where it came from...I haven't done a test myself...

Very odd. You might want to do that test. I wouldn't think a machine shop would intentionally do that build. The one I had was built by a buddy even after I did my best to talk him out of it. How I ended up with it is sort of a long story, but I did get my money's worth out of that engine.

Jim

Looks like a Buick ID number on that block.

Yeah...It wouldn't make sense...Its a "HI" block...Im going to do a compression test myself....

Carl....Im no expert but I don't think Olds heads can bolt to a Buick block...different bolt pattern....No?

A machine shop can make it work. Olds blocks simply have eight extra holes drilled and tapped.

Buick cast iron small blocks and later Rover engines are 4 head bolts per cylinder.

Buick/Pontiac 215s and early Rovers are 5 bolts per cylinder. Rover builders recommend not using the 5th bolt in order to get more equal clamping, which alleviates head gasket problems on the intake ( no bolt ) side.

Olds 215s are 6 bolts per cylinder.

The dimensions on the '4 bolts per cylinder' from line 1 are shared by all members of the Buick small block family, so you can always use any head on any block, you might just be limited to fewer bolts than the head is drilled for.


If the unused holes in the block go into the water jacket, they need to be plugged.

[www.britishv8.org]

fig 19 shows an Olds style block, fig 27 shows a Buick style.

Looks to me that its 5 bolts per cylinder

Also has these numbers stamped on the side of the block

So now after some more investigating im thinking this is a Buick High compression block , but the heads are still confusing...I thought Olds heads had six bolts per cylinder...im seeing 5.....

"Looks to me that its 5 bolts per cylinder. " Nope! The sixth bolt (per cylinder) is longer and comes right up through the rocker-supporting pedestal. "I'm thinking this is a Buick High compression block." The block doesn't directly effect compression ratio. To provide various compression ratios, Buick used pistons with varying volume dishes. Oldsmobile took a different approach: they didn't supply a variety of piston types, but instead Olds varied cylinder head combustion chamber volume.

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I'm surprised no one has commented about the first photo in the thread. At some point, someone purchased Offenhauser valve covers, an Offenhauser intake manifold, and I think a Mallory distributor. (Verify this, and determine which one.) They were spending money freely. There's no telling what parts they put inside the engine. And what machine work. They may have ported the cylinder heads. I think you'll have to take this engine all the way apart and inspect carefully to know what you have.

Oh...its hidden!! Yup....That's a Mallory....

They were spending money freely.


They weren't spending money freely on the the oil filter. That's a junk Fram unit.

I'd get a Napa Gold, AC-Delco or Wix on that before I fired it up. You also want to prime the engine, either with a pump priming tool or by spinning it on the starter after taking all spark plugs out.



Also has these numbers stamped on the side of the block


Being nitpicky, but those are casting numbers. Stampings are the "HI" numbers you posted earlier.

Which, by the by, "HI" should indicate a 1962 hi compression Buick long block assembly.

The block casting number also shows up in the Buick lists:
[www.buicks.net]


But I agree with Curtis, given how much money DID get spent on this engine, you really need to tear down to see what you have.

First step would be to do your own compression test though.

Second, if you continue to get those junk 100psi numbers, would be to hook the compression test plug up to an air compressor and see if you can hear air leaks in the intake/exhaust. This will tell you if the valves are sealing or not. If they really did put Olds heads on a Buick block, the rocker geometry is different and they may have used the wrong set of pushrods.

There is a serious problem with putting Olds heads on a Buick block. Now I'm not by any means saying that it can't be made to work, but my understanding is that the Buick deck does not have the internal bosses cast in place to allow proper drilling and tapping of head bolts in the top row. That's what I've always heard, but it's been so long since I looked carefully at one that I wouldn't want to go by memory on this, but would ask someone with a bare Buick block to confirm it.

But if indeed that is the case, it means the threaded hole those pedestal bolts go into is only something like 5/16" thick. That MAY be enough to anchor the rocker pedestals but it certainly will not secure the head bolts and since on this engine the rocker pedestal bolts are also head bolts they will never accept full torque. Perhaps the builder torqued the top and bottom rows to a lower figure.

In any case, despite the money spent on externals, given the head mismatch I would really have to question the internal assembly. Sorry to say that, and first step would be to verify the bolt boss question, but based on what I think I know them's the facts.

Jim

but my understanding is that the Buick deck does not have the internal bosses cast in place to allow proper drilling and tapping of head bolts in the top row.


while this is true of pretty much every pic of a Buick 215 block i've ever seen, what would prevent you from counter sinking a nut into the bottom side of the head?

after all, if 4 bolts / cyl is all that's really needed, especially in a non-boosted application, all you really want to do is hold the rocker shaft down with the top row of bolts.

It looks to me like a Buick block could easily be drilled & tapped to match the Olds block.

Buick 215:



Olds 215



I'm not convinced that they are not the exact same castings.



Edited 1 time(s). Last edit at 08/23/2015 04:17PM by MGBV8.