So i own a 1985 cutlass supreme with 3.8 v6 231 and a 200r4 transmission, the engine has a bad rod knock so i bought a 350 rocket out of a 1973 cutlass, with this bolt up to my 200r4 if not i have a 350 chevy v8 small block was gonna put it in my 64 but if itll bolt up to the 200r4 then might through it in the cutty any help or advice would be appreciated!

 

It will, but the longevity of the trans might not be all that long. You're more than doubling the torque of that V6 with the 350, and if it has a lot of miles on it, you may want to go through it when you have the engine out of the car.

 

the rocket 350 will? What tranny would u reccomend that would be a good bolt up fit with the rocket?

 

I would tell you to stay with the one in the car. They can handle that 350 just fine so long as they know what it's going behind. That trans with some different internal parts came in the Grand Nationals and the GNX and handled that power without issue.

 

Yes the Olds motor bolts to the trans. It will not bolt to the frame pads, however. You need to change the frame pads to the correct ones for an Olds motor and use Anchor P/N 2328 motor mounts to match.

 

This is one of the few times I'd suggest going with the SBC, simply because it's an easier swap than the Olds engine. Everything on the Olds engine is on opposite side of the car than the V6 or the SBC.

 

Sorry, Glenn, but I have to disagree. The amount of changes required will be nearly the same in both cases. In fact, both the Buford and the Olds have the A/C compressor in the same place. The Chebby puts it on the other side of the engine compartment.

 

Not gonna lie im new to these types of conversions but its extremely facinating and im excited to get into it, so converting to the rocket 350 can i use the old altinator and water pump from the V6 since theyre both olds motors? And would i have to get a different radiator then the one thats already in there?

 

The V6 is a Buick motor. The alternator, PS pump, and A/C compressor work, but you'll need the correct Oldsmobile mounting brackets and pulleys. The starter motor, flexplate, water pump, exhaust manifolds, and carb are all unique to the Olds motor. The radiator will need to be replaced primarily because you need more cooling capacity for the larger motor. Frankly, the simplest swap is a Buick V8.

 

buick v8 for my cutty? I mean if its a simpler swap id like to be able to get her running and driving while i got time during the quarentine

 

A Buick 350 will use the same motor mounts, accessory brackets, starter, etc as the V6.

 

damn i aint seeing any forsale in my area so imma just stick to the rocket 350 and try amd get everything to fit nice and well, any advice before starting?

 

I suspected the Buick motor would be more difficult to find. Just be sure you collect all the little parts you will need.

 

Last V8 Buick was made when, 1976? v8buick.com might be some help too.

 

1980, actually. The VIN X Buick 350 was available in the Riv, the Electra, and the LeSabre. I was surprised also.

 

The 350 Olds swap is pretty easy. Find a 307 Olds in a just about any 80 car, grab the accessories and mounting brackets, transfer them to the 350, and the engine will pretty much fall into place (assuming the frame mounts are swapped!).

As for the transmission, if it’s in good shape, get the TransGo shift kit with the big servo. I’d remove the trans while the engine is out, it will make the shift kit install much easier.


The 2004R trans in your v-6 cutlass is basically identical to one from a big Cadillac, and the Grand National. The only difference between them is the valve body, servo, and governor. The internal parts are all the same.

 

Oh sweet thank you guys!! Ill make sure to post some more questions if i got em😎

 

Ok long story short after thinking about it carefully im going to use the sbc 350 for my 85 cutty, i have all the parts for it except the motor mount because im not sure which ones to use, and any advice? Thanks in advance!

 

my advice? Stick with the Olds. No brand “X” chebby engines in a Olds!!!

And I don’t want to hear any crap about factory sbc installed in Oldsmobile’s. It was wrong then, it’s wrong now!

 

i have this one candy painted and all chromed out already haha, but i appreciated the advice tho!

 

before you even consider the chevy,you better make sure you have the dual pattern trans to fit either the chevy or the bop engines.

 

i have a 200r4 tanny in it so it should fit but if it doesnt a have a th350 i can throw in it

 

You know that the shorter TH350 requires a different crossmember than does the 200-4R in the G-body, right? Unlike the older cars, you can't just slide it forward.

 

Ah i see, what kind of cross member do i need? But will the 200r4 fit?

 

You would need the TH200 crossmember to install a TH350. With the exception of the very early cases, every 200-4R is unisex, however.

 

My dad and I made this swap many moons ago. It was not hard and we used the stock transmission. It was a casual driver and not a hot rod so the transmission done just fine behind the 1970 350 4 bbl Olds engine. We had to find the correct fan shroud and also had to find a transmission cable that would hook to the carburetor we had. I can't really remember now what cable we had to use for that? Been to long ago.

 

Mr. Joe
Good Afternoon
I wanted to verify if I currently have the Automatic 200 metric trans with the Buick 3.8 liter in my
1985 Olsmobile Cutlass Supreme a small bock chevy with the Right frame mounts and engine mounts.
Chevy 350 turbo transmission should bolt up with no issues.
I appreciate your input
John
1985 Oldsmobile Cutlass Supreme (Rear wheel drive)

 

John, the TH200 pans look similar (square-ish with one corner cut off) but the TH200 uses 11 bolts on the pan, the TH350 uses 13. If your trans is a TH200, yes the short-tail TH350 bolts in with virtually no other changes.

 

The TH200 is a one piece case (no removable extension housing) the TH250 looks very similar to a TH350 but has a band adjustment screw on the drivers side (I think).

 

From what I remember, for my blue 1979 Calais when I went to to a 200r4 my crossmember had to be moved a few inches, I'll have to look and see, I think it was a few inches back.

 

The 1978-1988 A/G body cars use completely different crossmembers for the 200-4R/TH400 as compared to the TH200/TH350. Unlike the earlier cars, the crossmember is not straight across and the frame is not symmetric. You can't simply slide it back, at least not if you want the frame to be structurally adequate. The 78-83 cars don't even have the correct reinforcement on the frame to accept the 200-4R crossmember. There is an aftermarket part available to correct this.

 

The 2004r is a OD trans and the 200 is just a 3 speed so you should know from when you were driving it which trans you have. Also the shift indicator quadrant should tell you.

 

Mr. Joe Good evening I wanted to know if you knew which frame mounts and engine mounts that would be needed to complete install
of the 350 SBC and the 350 short tail transmission also will the drive shaft need to be modified in length to fit.
Thank you for your input
John Moore
docholiday000@aol.com

 

it appears to me that the v6 trans cable is 2" too short. By using oreillys website and changing the selection from 3.8 v6 to 350 v8, I found the v6 is a 35" whereas the 350 rocket is a 37" cable.