Technical 389 in a 55 Pontiac?

I know the blocks are all supposed to be the same but how much changing is required to put a 389 and later trans in a 55 Pontiac where a 287 auto was?

 

Well, if you can find a '59 or '60 389, it's almost a bolt in. What "later trans" are you talking about? Makes a difference.

 

Probably be an early 60's motor and trans. Or a th400

 

sounds like a lot of work to me

 

In the mid 60's I put a '60 389 engine in a '56 sedan, using the '56 trans, an absolute bolt in.

 

its so close a bolt in is all you can say !

 

Isn't the 287 front mount and 389 side? also I have heard the oil pans are enough different on some to cause issues?

 

Don't forget that big car Pontiacs until '65 model year (exception being 64 Tempest and GTO) used a transmission mounted starter. You can use a later block with 61 thru 64 transmissions (I put a 69 Ram Air 3 in a 64 Grand Prix with the slim jim trans) but I'm not sure on earlier ones.

To use a TH400 you need a adapter plate to mount the starter to the bellhousing. I found a plan online a long time ago for making it but I can't remember who had it posted.

 

The front cover and mount can be used on the '59-'60 engines.

 

The 389 I am looking at is mid 60's as stated earlier. Looking for someone that has done that swap?

 

i have a post here where i put a 400(pontiac) 67 engine in my 1958 gmc truck(370 block and 4speed gmc auto)
new engine needed a 1960 timing cover and i made a adapter plate to fit 700r4 chevy trans.using same mid engine/trans mount and a new rear trans mount.mid mount is welded to adapter plate.
ken sweden

 

Thanks but not really what I need for info.

 

The 55 timing cover on the later motor should mnt the front easily. The problem is with the later trans. If you use a conventional x-member towards the rear of that later trans you now have both eng & trans mounted in the middle with no side support. It'll rock all over the place. I think fabbing side mnts for the later motor's gonna be a lot easier than trying to duplicate factory side mnting for the later trans. Short answer-not a bolt-in

 

Have you read through the multiple Pontiac-specific forums that exist?

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Check the Performance Years (PY) website ...forums. If you can't find help there then I don't know where you will find it...it's an all Pontiac site!

 

Thanks guys I will check the Pontiac Forums

 

Thanks, I just talked to a machine shop in town here that has a completely redone 56 317 that the customer never picked up. They are expensive, but I think I can get it at a fair price, he will let me know Friday. Rebuild on the current 287 is in the $4K to $5k range depending on what can be saved in the valve parts. Parts are available but 1 year only makes them expensive.

 

Keep your poker face. If you don't buy that 317, he'll probly end up married to it. LOL. That said, he almost needs you more than you need him. Especially if he got some "front" $$$ from the customer

 

Swapping the front covers on those is real simple and a guy wants to check the timing gear on any Pontiac V8 that isn't fresh anyhow.

 

Yep I have already made him aware that I might be his only buyer ever. I think I can make a pretty good deal on it. Plus the 317 would be a nice upgrade from the 287.

 

The early "reverse cooling" 55-59 covers I don't believe would work on a later engine. I did use a 60 cover which still can use the 55-58 front mount set up on a 66 389 to help mount it in my 55.

 

Hi, Before you plunk down any hard cash, look at the pontiac custom safari web site. The key to putting a later 389 into that 56 is getting a 60 389 front cover. It's cast iron an it will be compatable with the later model (61 up) cooling system. Try to go with a later (post 60 engine) you will have a lot more transmission options.