pontiac 389 ?'s

i am wondering if anyone can help me out here. i am looking into buying a th350 in a corporate housing to throw in my 60 catalina to replace the pos slim jim that is in there. my problem is that i know there is a couple of year splits on that engine. anyone know the difference between a 1960 389 and a 1964 389? i know the intakes are different and there are some water journal differences, but i can't seem to find out if the bellhousing bolt patterns are the same. any help would be appreciated.

 

A corporate GM TH350 won't fit a Poncho motor prior to I believe '64...

 

Yep, Mine misses by one year at '63. There are adapters available but pricey.

 

thanks guys. it was going to be less expensive than resealing the stock trans but if it doesn't fit thats a problem.

 

Sorry to read you're in hell. Let me help you a bit. First of all, if your trans is original, you do not have a slim jim. Slim Jims or rotohydramatics were used in Catalinas, Venturas and GPs only from 1961-1964.

You have a 4 speed hydra matic.
Now, on to your question.... Wilcap makes an adaptor for your engine. Look them up on the web.

Bellhousing interchange is 1955-1960. Vast changes were made in 1961.

Hope this helps you down there in hell.

Oh, I have a '60 389 in my race car. So far it has gone 6.77 at 200mph. Thats a pretty tough little motor.

Steve
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Hello there, I have a '60 Pontiac Ventura Sports Coupe with the Hydro. It was rebuilt, but needs adjusting to make it right. I'm gonna hold on to it and see how far I go. I though they were the better of the GM transmissions out there, compared to Olds/Chevy. Buick having the Dynaflow.

Ken

 

I'd try to do some more research and ID that block you never know what's been molested on that car in 49 years.

 

yeah, i got a friend with an edsel that was one of john gacy's victims.

 

Nothing wrong with the four speed Hydro you've got now, it was a damn good transmission. If you are having trouble getting your mind around rebuilding it, that's something else. Your 60 is a side mount engine, so any later Pontiac V8 with a block mounted starter would be an easy install. Just be aware that some of the 70 and later blocks might need the bosses drilled for your motor mounts. Would be a chance to jump up to a 455 too.

However, if you're going to go to the trouble of replacing the transmission, instead of the Turbo 350, consider the 200R4. The lower first gear, overdrive fourth gear, and lock up converter make it far more desirable for a driver in this day and age. The overall length is very nearly the same and they even use the same driveline yoke.

 

i think i am just going to pull the four speed put and reseal it. as much as i would love to stuff a larger motor into it the 389 runs strong as hell, and in the end it is just a weekend cruiser for sure. i appreciate everyones help on this though.

 

There's a slight bolt pattern change, but with the '64 block adapter you should be able to bolt either the dual-coupling hydro or the slim-jim to the '64 block, and with the 60 adapter either trans to the '60 block. The actual trans case pattern appears to me to be the same.

1964 was the first year to have provision for the block starter.

As noted, you could put a newer motor in using the stock side mounts and adapt the trans mount, but there's not a lot that bolts to the '60 block itself.


Personally I wouldn't run one with another transmission, that 4-speed is a damn good transmission if you don't beat on it too bad, and the car will go like stink with it in.