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Old 12-17-2020, 11:27 PM
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Rocky 389 Rocky 389 is offline
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Default 55-60 engine in a 50 coupe???

I went back 5 pages to look because I thought somebody on this site had either done it or knew somebody who did it. I've adopted a nice little bronze 1950 coupe with the straight 8/hydramatic.
Been soaking the engine and it came free without too much struggle. Gotta repair some fabric covered wiring and I'll be ready to light it off. But even if it runs sweet, doesn't smoke I know me. I won't be happy with another straight 8 car. My 34 ford coupe with a Pontiac 370/muncie 4 speed runs like Jack the bear. I'm addicted to the performance and would like to either
1.....find a 59-60 389 to build for the Pontiac coupe..or
2....Pull the 370 engine and trans from my ford coupe and sell it as a roller.
But the point of all this is to find if anybody here has used the straight 8 motor mount brackets to bolt in the V/8 engine. I also wonder if the 55 pontiac bell housing would bolt up to my 1950 transmission. If I'm able to score a good 55-early 56 [870-860 model] would it bolt into my 50 chassis....thanks in advance!

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Old 12-18-2020, 01:35 AM
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Bill Hanlon Bill Hanlon is offline
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Rocky, you may be two thirds in luck. According to 1966 Pontiac Chassis Parts Catalog, 1939 through 1957 standard transmission Pontiacs (straight 6, straight 8 and V8) use the same rear motor mounts (522657 on the left, 522656 of the right). The front mount has a part number 508748 for the straight engines and 761748 for the bent-8.

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My Pontiac is a '57 GMC with its original 347" Pontiac V8 and dual-range Hydra-Matic.
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Old 12-18-2020, 02:03 AM
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Thanks, Bill! That helps a lot. Now, I need to formulate a plan on what parts to use for this car.Stick or automatic trans.

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Old 12-18-2020, 02:54 AM
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Jack Gifford Jack Gifford is offline
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If you wanted to use the dual-range HydraMatic, it wouldn't surprise me if the '50 Hydra-Matic case could be used on the rear of a '55 or '56 two-piece bellhousing. And I'm guessing that a later torus cover would mate with the '50 front pump. Beefing the hydro somewhat to handle the power of a mild V8 wouldn't be difficult.

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Anybody else on this planet campaign a M/T hemi Pontiac for eleven seasons?
... or has built a record breaking DOHC hemi four cylinder Pontiac?
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Old 12-18-2020, 04:50 PM
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Rocky 389 Rocky 389 is offline
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Yeah.....but I haven't found any written material on the subject. I'll search further before I buy any parts....thanks, Jack. If I indeed could reuse my 1950 transmission it would solve some kick-down/ line pressure linkage problems. I'd love to slip a 59-60, 389 in the car with stock green engine paint and early V/8 strato streak valve covers. Tell everybody this car was a test mule by GM to test the idea of introducing a new V/8 engine...and to test out the possibility of even using 12 volts...
One good thing is the straight 8 radiator has the inlet and outlet in the right places for a Pontiac V/8.

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Old 12-18-2020, 06:57 PM
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61-63 61-63 is offline
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Kind of related I bought a '50 Chevy 2 dr sedan from a fellow in 1960 that had a '57 Pontiac engine in it with a Lincoln standard shift three speed behind it. The top end (heads and higher) of the engine was in the trunk of the car when I got it. I put it together and got it running and proceeded to blow up every Lincoln transmission in SE Texas. After I went through all of the transmissions I sold it back to the guy. He is the one who put the engine in the car so I can't comment on how he went about it. The shifter for the transmission was a crude three on the floor thing fabbed up from the original column shift in the Chevy.

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Old 12-19-2020, 03:30 PM
421mike 421mike is offline
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Default transmission

Just a note on stick transmissions. I built a '56 316 engine back in the day, in a 56 coup that came with the stick. The trans had very heavy duty gears but... the case wad like less than a 1/4 inch thick on the bottom. Shame too but the case could not handle the torque of the engine and every time I got on it hard it would blow the bottom all over the street, not making me any friends with the neighbors. If you want to run a three on the tree transmission, find a good T-85, you will not blow that one up without some seriou trying. (JMHO) Mike

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Old 12-21-2020, 11:52 AM
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Thanks, Mike. I learned my lesson with the infamous selecta-shift transmission back in the 60s. After running through 4 of the 6 bolt transmissions in my 57 Pontiac I swapped to a '59, 389 engine with the '59 bell housing and a muncie 4 speed.
The old transmissions were holdovers from the 1940's and in addition to being fragile, they had gear ratios that were never made for heavy cars with hiway geared rear axles. First gear was really high, making for a lot of [10 inch] clutch slippage, even with the 3.63 rear gear. I went through 4 clutches with that car too. If I sound bitter, I am. I swear, it seemed like I spent more time under that car than driving it.
Swapping to the Muncie with a 11.75" clutch really woke the car up and no more drivetrain problems.
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Old 01-15-2021, 03:09 PM
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Quote:
Originally Posted by Jack Gifford View Post
If you wanted to use the dual-range HydraMatic, it wouldn't surprise me if the '50 Hydra-Matic case could be used on the rear of a '55 or '56 two-piece bellhousing. And I'm guessing that a later torus cover would mate with the '50 front pump. Beefing the hydro somewhat to handle the power of a mild V8 wouldn't be difficult.
The 1950-54 Pontiacs used a flat pan hydro. The 1955-56 Pontiacs used the slant pan hydro. If you put a flat pan hydro to the 55-56 bell housings, the transmission would be slanted like the slant pans. Then you would need to get a slant pan, and pickup tube. Also the linkage would have to be modified somewhat.

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Old 01-21-2021, 02:19 PM
Poncho60 Poncho60 is offline
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Don't know if you are looking for an engine or not. There's a couple on the HAMB. 58 tripower (pricey), 56 base engine $500 obo.

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Old 02-08-2021, 12:57 AM
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Yeah, I saw the engines on the HAMB as I am a classifieds moderator. I'm not buying anything until I ascertain the condition of the straight 8 and hydramatic that's in the car now. Thanks for the heads-up though.
I'm down to about an hour's work to get this engine lit off but it's just been too damned cold in my garage to play. In fact, I've been using the trunk of the car for cold storage of pop and food!
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Old 05-17-2021, 01:04 PM
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Welp, I got the straight 8 lit off to find it has a blown head gasket between #77&#8 cylinders. While it was running on 6 cylinders, I found all the gauges work, charging system works and the engine holds 40 psi oil pressure. Dropped it in forward and reverse gears and they work. Neutral safety switch is busted, leaving the reverse lights on all the time the key is on and starter button not working..used my remote starter switch.
Got a Pontiac buddy who made me a brother deal on a 400 Pontiac engine and I have an extra 4 speed transmission. Who knows? I just may do it. In the meantime I polished up the grille/front bumper as a motivator.
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Old 05-17-2021, 03:17 PM
Poncho60 Poncho60 is offline
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I think one of these business coupes would be cool with the OHC sprint six and 5 speed.

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Old 05-17-2021, 03:33 PM
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The chrome looks really nice.

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Old 05-17-2021, 10:41 PM
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I have a 50 fastback with the straight 8 and standard transmission. It is driveable but I need to do a good bit to it. I envy that front grille! Mine is pretty much toast! I wonder if there is any way to hook up a more modern (60s-70s) 4 speed to the straight 8?
Have you checked the Pontiac Chieftain group on Facebook? If not, here is a link: https://www.facebook.com/groups/150467135123404/

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Old 07-06-2021, 12:51 AM
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Thanks for the link. Got the head off the straight 8, replaced head gasket and freed-up a stuck #8 exhaust valve. Just finished up torqueing the head bolts down this evening. Hope I get some time tomorrow to finish up hooking up the throttle linkage, spark plug wire organizer etc etc. Looking forward to hear this baby run on all 8 cylinders.
Next project is replacing engine and trans leaky gaskets, going through the brakes etc.

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