Technical 1951 Pontiac Straight 8 into a 33 Pontiac.

I have access to a 1951 Pontiac straight 8. I'd like to swap out the straight 8 in my 33 Pontiac as it's locked up. Is there a way to do away or adapt the enclosed driveshaft? I'd rather either keep the original rear end or swap something in that I can still run the original wire wheels. If I swap I'll have to put in a hydraulic brake system for the rear. I'd rather keep it as simple as possible.

 

Seems like a poor choice for an engine swap. They're horrible, even in a '51 Pontiac...
Edit: To try to be helpful as opposed to just snarky, if you have one, and that's the reason, using a bad engine just because you have one is a not a particularly good idea. They are saddled with (most likely) a huge, heavy, inefficient 4 speed Hydromatic. You'll end up spending a fortune to convert your closed drive, and if you're gonna swap a different rear end, might as well drop in a modern power plant. A Chevy 250 or 292 and 700R4 would me my choice, and a rear end from an early 90's Cadillac Fleetwood or Buick Roadster wagon. They're 5 on 5 (which I think your car has) and even if they don't, drilling axle flanges is no big deal. Don't ruin your car with the straight 8...

 

He's talking about swapping the engine, nothing was said about the transmission. I'm not that familiar with Pontiacs that old, but would think if you're just switching one straight 8 for another it should be straightforward. They weren't known as a hot rod engine but I sure wouldn't call them horrible.

 

I don't want a modern engine in it. Rather keep it a straight 8 as it came.

 

The '51 straight eight traces roots back to the thirties- that's why it's so terrible (it's not terrible. It's just poorer than a lot of engines in terms of making big power and fuel economy, and the dynamics of it are way worse than a V8.) so it's not an inviable swap. The mk1 Hydra-Matic is actually more efficient at cruise than the TH350 because its fluid coupling doesn't slip as much as a torque converter. They're just picky about fluid, heat, phase of the moon and not as smooth or trouble-free as the later transmissions.


Horses for courses.

 

Should be a viable swap.... the straight eight in its basic form was used for about 20 years. But.... there no doubt were some subtle changes. Can you get the two engines side-by-side to compare? My guess is you'll see some motor mount changes, accessory changes, etc., but it shouldn't be insurmountable. You might try the Pontiac-Oakland club (they probably have an online forum), as I would imagine this swap has been done more than once. Good luck!

 

Probably easier and cheaper to just rebuild the original.

 

cracked block

 

I thought this is a HOT ROD forum! Any and all things possible.

Go for it, Casper50. I never had a Pontiac as old as yours. Did have a 1948. In 1957!!
I have no idea how to make it fit but bet you will do so.
Good luck.

Ben

 

Well, the length and weight certainly won't be a problem. If you're lucky, they're like early Chevrolet sixes that had one block pattern for the bell housing from 1937-62.

 

Does anyone have an old J.C. Whitney catalog? IIRC, they sold a steel brace kit for the Pontiac straight eight. It was so long and with the motor mount system Pontiac used, the block would literally sag.

jack vines

 

I have a 50 and a 39 with straight 8s and other than the carburetor/intake I can't see any difference. Does your car have a manual or automatic tranny? Not that I see any great difficulty in swapping just the motor.

 

33 has a manual 3 speed. It's also frozen. Wife want to drive it when it's finished so I need the auto. Sounds as if it will become a real headache but I'll work through it.

 

That wifey thing!! I installed AC in mine so wife could ride along. You guessed it! ONE TIME. I seldom turn it , AC, on.

Ben

 

I used a Toyota rave 4 rear end in my 34 chev truck .
57 inches wide wms to wms . 4.11 posi .12 inch hydralic brakes , same 6 bolt pattern as chev, whole gear pot pulls out same as a 9 inch . 33 spline axles , parts readily available ,cheap from rock auto .

 

Sounds like a "Block-brace"(anti-sag)...is a smart choice. You could prolly make one!
Standard hot rodding tricks like split exhaust.....maybe add another carb onto that looong intake(or bigger one)...
Delta Cam or others could re-grind the camshaft for ya...maybe mill the head a dab to bump up that miserable CR.. free flow muffler(S)................you-be-in-business!!!
6sally6

 

It isn't terrible at all, i rebuilt my original straight eight and it's going strong, no oil consumption, running up hills like a young girl, starts on the first pedalpush and makes nearly 16 mls a gallon. You can do 300 miles in one piece without any stress. With my small tent camper on the hook that weight including some camping equipment about 600 lbs i also had no lack of power.
and it's easy to fix, too.

 

40two I agree. Not everyone needs or wants lots of horsepower in a car. Reliable, smooth running and easy maintenance is a huge plus for some of us.

 

Yup, done 4500 miles on this one. Needs a valve job because it sat for 6 months outside and still has a sticky inlet valve.

But, it's smooth, has an exhaust note you don't hear these days (inclusive of the very particular flathead type noise you get, the hissing chatter), starts stops and doesn't overheat. Has a little trouble getting up to 55 im a hurry by today's standards but is really happy if not pushed hard down the highway.

 

55 in a stock 33 will be plenty fast I'm sure.

 

Yup.

 

Congrats on keeping it on a similar platform, and all Pontiac.

Performance parts (aluminum head, twin carburetor intake) were produced once, but you have to have a crystal ball to find them today, and own an oil well to pay for them if you do find them.

Even stock, the 1951 engine produces 50 percent more power than the 1933 (116 hp versus 77 hp).

And you can add 5 more by changing the Carter 720s (original) to the Carter 2122s (1954 version).

Should make a nice running car!

Jon.

 

You mean like this intake? I picked it up at a local swap meet about 5 years ago. It is going on my 50.

 

It would be a lot easier to teach her how to drive the manual and once she learned she would love it. My wife does.

 

fyrffytr1 - better lock your hood!

I haven't seen many of these, but memory (sometimes faulty) remembered one drilled for the 4-bolt carbs.

And ditto on the wife driving a manual. I taught mine to drive a 4-speed in a 12.2 second Corvette about 1966.

Jon.

 

Used to have this stuff hidden away for when I found a '54 Star Chief coupe. Didn't get to use it ...

 

302GMC - that is the one I remembered.

Jon

 

This one will fit the motor but I will either have to get adapters for the four bolt or put three bolt carburetors on it. I think a set of Strombergs would do the trick.

 

302GMC
I noticed the aluminum head in your first picture. I check the Pontiac classifieds every day here but a few years back I missed one day and that was the day someone posted two of them for $800.00! Of course they sold immediately. I even messaged the buyer to see if he would sell one but he had plans for both.

 

I think that would way cool. Yes it will take a bit more effort. But how cool will it sound and look. With multiple carbs and duel exhaust. If properly built and maintained it should be dependable. Who says you have to run an auto. But if an auto necessary you could adapt a turbo 700 to it.