Swapping out a TH350 for a 700r4 pros/cons?

[DBK81]

Currently have a very fresh, less than 5,000kms TH350 that the PO installed, I'd really like to have an overdrive Trans as I'll do most of my driving on the highway. What are the pro's and cons of doing this swap? Current motor ZZ4 350 Chevy Pref crate motor.

[1972BlueC20]

I'm interested in this too. Subscribed.

I want to do this as well one day.

What modifications are needed and what about the shift linkage and shift indicator lining up

[DBK81]

It's a relatively easy swap, drive shaft might need to be shortened depending on how long the TH350 a guy has 6" vs 9" tail, I'm running around 400hp and do have a bit of a heavy foot so I just want o be sure the 700r4 will hold up, lord knows the TH350 can handle my 400 and more.

[Z10]

I did this swap last year with a ZZ4 also. Other than shortening the drive shaft, which cost me about $150 with new u-joints, it was pretty straight forward.

I now have a little over 8000 miles on the engine/trans and it is running great. I'm also turning about 2200 rpm at 70 with a 3:73 rear and getting a hair over 16mpg on the highway with the cruise on.

I'm using a GM rebuilt 700r4 from a 91 Corvette, purchased from a local Buick house.

I'm very pleased.

You can see what I did on my build thread link below.

[DBK81]

Originally Posted by Z10

I did this swap last year with a ZZ4 also. Other than shortening the drive shaft, which cost me about $150 with new u-joints, it was pretty straight forward.

I now have a little over 8000 miles on the engine/trans and it is running great. I'm also turning about 2200 rpm at 70 with a 3:73 rear and getting a hair over 16mpg on the highway with the cruise on.

I'm using a GM rebuilt 700r4 from a 91 Corvette, purchased from a local Buick house.

I'm very pleased.

You can see what I did on my build thread link below.

That's awesome, I'm also running 373's, I'm going to talk to a local shop to see what they can do and if they are interested in buying my fresh TH350. I just need that OD, it has to happen.

[1972BlueC20]

What about shift linkage and the gear indicator lining up on the column?

[Gatorman]

I did a similar swap in a 71 Nova a few years ago. Also was running a crate motor. Go to Bowtie Overdrives. They have everything you will need and are easy to deal with. In addition you can call them and they are more than willing to answer questions. Dale

[Mikem_72]

Originally Posted by 1972BlueC20

What about shift linkage and the gear indicator lining up on the column?

I didn't have to make any adjustments to the linkage for the indicator.

[davepl]

I would recommend the 200-4R. Properly built, if you're pushing more than stock horsepower (they're likely fine for our stock power levels, I'd bet).

If I recall correctly you don't need to change your driveshaft if you're going Powerglide or TH350 to 200-4R, whereas the 700 may require a change.

When I did mine it was pretty much a bolt-in in place of the TH350. Change the lens on the columns to a 4-speed (overdrive aftermarket) lens, and the detents are in the trans, not the linkage, so that all just works.

[davischevy]

I am running a 700r4 behind a big block with 3.73 gears in a 71 GMC Longhorn.

Besides what has been mentioned so far, don't forget the little bracket for the TV cable attachment to the carburetor.

I had a ball last week on I-40. The traffic was running 75 and the old GMC was cruising effortlessly. Actually, it wanted to be cut loose from that slow grind.

[Mikem_72]

I was running a 350/350 set up and swapped to a 700r4 around 6 months ago and love it. It was pretty simple, I did have to shorten my drive shaft as I was running a short tail TH350. I also had to buy a Lock up kit for the torque converter to run off vacuum. I got the kit from Jegs and also purchased the adapter bracket for my carb from them. I would say that's the most critical thing is getting the geometry and shift points right on the TV cable. I have the parts I used on my build thread.