Picked up a 63 Grand Prix. The "slim Jim" trans leaks bad and engine could at minimum use a refresh. Thinking I will swap a 200r4 into it because of size and gaining a overdrive. So being a 63 it will require a expensive adapter kit to swap a different trans in it. Should I just look for a newer pontiac engine? I'd like to keep it pontiac powered. Or should I just freshen up the original 389, buy the adapter kit and swap a normal trans in it.
Butler Performance sells the adapter plate for $250 which isn't terrible, and is certainly less than a whole other good running engine would cost. However, if your engine is tired it may be worth looking for a newer engine/trans combo. Note that there's always a big debate in the Pontiac community about whether a 200R4 is going to last behind the torque of an Pontiac engine...some say it just won't work, others say it will require expensive modifications. My opinion is it depends on how the engine is built as well as how you drive the car.
I thought the whole kit was close to 1k for the adapter. I obviously need to do more research haha. I'm not worried about the 200r4. I can build em myself as well. The one in my 89 TTA did pretty good with the car making decent power. I also plan on putting one in my 66 GTO to replace the st300. I like them. I know the trans tunnel is limited in these cars so I figured this would be the best fit. I got LS stuff stacked up like cord wood.... I just dont want to go modern engine in this one. As far as engine build. Stock is what I'm after. Smooth idle an all. I want go get on the highway and keep it in the fast lane if I want to
Build the motor, when I built my 66 Gto 389 I used standard 400 pistons and had the cylinders cut to fit them. Cheaper than custom 389 pistons at the time. And I'd put a turbo 400 behind it and be done.
Yeah I did the same with the 389 in my 66 gto. Still gonna get it back in the car. It's mostly stock. Mild cam etc. The grand prix i want to do pretty much same thing except it will be getting a overdrive.
Find a 64 and newer engine. $80 for a 200R4 adapter. you can't use the stock starter with a later transmission without expensive adaptation. Pontiac engines are not that hard to find, even in ohio.
200 4 r is a lot stronger than people think . They'll hold up in an 11 second 455 car with slicks,, without any expensive parts.. Real world experience here...or I wouldn't post it.
Holy crap! Two of the really old HAMBers Spudz and Enjenjo on the same thread! I wondered where you guys went. I'd also go with a 400 or maybe a 428/421/455 and use a 350 or 400 turbo with 2.69 rear gear. Your 63 may already have a high geared rear but if not a 2.69 third member should be a piece of cake to locate. . If you choose the 400 turbo you'll prolly have to do a little beat down on the tranny hump if your car came with the slim Jim P.O.S. but if it came with the bigger hydramatic the trans tunnel may already be the big one. Great cruisers and aside from the junk trannys the only bad thing about those 63 GPs is the 8 foot long quarter panels with no chrome moldings to protect from door dings. Man, if thos 1/4s are banged up, it takes some good body work to fix them right.
What's up! Yeah it's been a while! Yes it has the slim jim trans. I am going to put a 200r4 in it fo sho. I already have it, just waiting on parts for me to freshen it up. And yes its huge compared to my 66 GTO. I love it. A 421/428/455 would be great! Will definitely keep my eye out. I'd be fine with a newer 389/400 as well. Hell I hate to ditch the 389 in it but I'd rather not spend 800plus on the starter adapter kit.
The 200r4 I'm going to build for it is a unibell so it will bolt right up to a newer Pontiac motor. Yeah I guess if I cant find a good drop in pontiac engine when I'm ready, I will have to fork out for that expensive kit. The 389 in it runs ok but I'm sure its tired too.
All GPs and Cats came with the Slim Jim.The console wouldn't fit the floorboard otherwise. That combo came with 3.08s
In 64 I worked for a Pontiac dealer. We had a guy buy anew GP and brought it in a few weeks later to have us fix the door dings, and put Catalina trim on it.
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