Hi, recently I bought a 85 Delta with a knocking 307 and I've been looking for cheap options to get it on the road. I've found a guy with a rocket 350 from a 71 cutlass and a 350 powerglide trans. The engine needs rebuilt but it's at a very reasonable price (for what a used 307 cost) for 350 and trans.

My mechanic that's doing the work asked me to find something that will pretty much bolt right in. I know the engine should work just fine but I was wondering if the trans will replace my TH-200 without too much effort. Thanks a lot and is there a rebuild kit you guys would recommend for the rocket 350?

 

The Olds 350 and Olds 307 are externally identical, so yes, the motor is a direct bolt-in. There are a few things you need to be aware of, however. First is that you need to completely swap the water pump, pulleys, and accessory brackets from the 307 to the 350 as a matched set. Do not mix and match brackets or you'll likely have a belt alignment problem. Also, pay attention to the two spacers between the PS pump bracket and the block and be sure they go back in the correct places.

Use the motor mounts from the 307 on the 350. If you need new mounts, get the ones for the 1985 Delta (Anchor P/N 2328). Use the exhaust manifolds from the 307 for a bolt-in exhaust system. If you plan to convert to duals, use the 350 manifolds and cap the crossover.

If you plan to delete the computer-controlled carb and ignition, you will need to use a non-computer carb and distributor. Also, be aware that the computer controls the A/C clutch and uses the throttle position sensor on the original carb to signal when you are at wide open throttle, causing the compressor to disengage. If you eliminate the computer, the compressor will not disengage at WOT.

The 307 starter is smaller and lower torque than the 350 starter. It will work but may not work reliably as it ages. You might want to use the larger 350 starter. Use the larger oil filter for the 350 instead of the small one for the 307. This will require a minor rebending of the AT cooling lines to clear.

As for the trans, you need to figure out exactly what each one is. Your 85 could have had a three-speed TH200 or a four speed 200-4R. Also, there is no such thing as a "350 powerglide" transmission. The stock trans from 1971 would have been a TH350 three speed. This will bolt in place of the three speed TH200. If, however, you have a 200-4R, the trans mount is in a different place and those cars use a different trans crossmember. The 200-4R crossmember will not work with a TH350. You will need to find a crossmember from an 85 with the TH200 trans. The driveshaft is the same in all cases, however. Of course, if you do have a 200-4R, the 350 motor bolts right to it.

 

Thanks again Joe!! What's the easiest way for me to identify which transmission I have in my Delta? If I don't have the 200-4R will I be able to get an adapter plate so the 350 motor will bolt in?

I'm making plans with the guy now to pick up the engine and trans. He's pretty adamant about the trans being a powerglide. If that's the case I'd rather keep whatever I have in my car now since it'll mainly be used for cruising around.

 

The TH200 is a 3 speed trans and a 200-4R is an overdrive (4 speed) trans. The 350 will bolt up to it with no issues.
The one thing he didn't mention is if you do have the overdrive trans and delete the computer then you will need to get an aftermarket lockup controller for the torque converter.

 

If the shift indicator in the dash says P-R-N-O-D-S-L, it's a 200-4R. If it says P-R-N-D-S-L, it's a TH200. The 350 will bolt to either 1985 trans without an adapter, but I thought you wanted to use the TH350 trans from the 1971.

 

Both 1985 transmissions used a lock up torque converter. You can activate the lockup in a number of ways, from a simple toggle switch to an aftermarket controller, or you can just not use it.

 

I'll have to check out my dash when I get home. The guy said the trans with the motor is definitely a powerglide. If it was a TH350 I'd put that in but I don't think a 2spd trans is going to be useful for a cruising car.

 

Thanks again for the advice. I'm waiting to hear back from my mechanic's friend on how much he wants to rebuild the rocket 350. I don't think it's something I should tackle myself, just because I've never done anything like it before and don't wanna waste money on a kit and put it in wrong.

I plan to drop the engine in as you described, Joe. The car runs now and everything seems to work okay asides from it having a hard time start after sitting and smokes quite a bit that first fire up and the engine knock. Once I drop the engine in and get her tagged I'll gather parts needed to do away with the computer, maybe get tubed headers and dual exhaust. I plan to get it tagged as antique before I do any performance upgrades.

 

"The guy" is clueless.

Olds never used a Powerglide. Olds DID use a two speed trans from the 1964 to 1969 model years. That was the Super Turbine 300, which was also called the Jetaway. It has nothing in common with the Powerglide other than the fact that it has two speeds. For the 1971 model year, the ONLY automatic installed behind the 350 Olds from the factory in a Cutlass was a TH350, period. Some big cars used a TH400 (actually, the low-perf TH375) but there were no two speed transmissions offered by Olds in 1971.

 

I'll have to ask him for some numbers before I leave today. I'll be driving about 2 hours and hauling it with my cavalier . I'm pretty sure it'll haul just the engine fine, not sure about the trans also. He said he'll let both go for $150. So if it is a TH350 I'm not gonna want to pass that by. I'll try to confirm with him later, the story is his dad has had the engine and trans sitting in the garage since 88' and he's just trying to make room so I don't think he knows much about either.