I have a 1983 Lesabre that came with the 307/th350,I put a 455 in it and kept the 350 trans in it but havent ran the car yet does anyone know if that trans hold up to the engines massive torque.
Many times the 350 trans is underated , but built right it is tough . Several years ago Randy New had a 72 GS 455 with a 350 trans that held the G Stock Automatic national record . Pulled the front tires every launch and never had any major troubles with the 350 trans . I like them because they are about 75 lbs lighter than 400 and take much less power to operate .
great street trans as the cable downshift will make any motor responsive when setup right fast positive downshifts put a 3 series gear in the rear end you will like the setup
I heard the only thing they really need is a heavyduty sprag. I knew a guy (rest his soul) who used to have a 500" Lingefelter BBC in front of a th350 in a mid eighties Chevy Stepside. Mild torque convertor and healthy gears, ran well, no trans problems. I did have to replace the cam once as he used to idle around all day in the truck and it finally took out the cam from lack of oil and high spring pressures. The 'new' cam was a hydraulic roller. As much money as he had-to do whatever he wanted and it didn't really matter in the end. Sad story for me, but the bottom line is , YES the TH350 can handle quite a bit of torque.
I've got a TH-350 that has a basic shift kit in it, behind the old 350 it would chirp the tires going into 2nd and 3rd at wot 5000rpm shifts. It's currently behind a mild 464 (9.5 CR, 212 cam, shorty headers), and it's doing well. Only issue is that if at wot shifts at 5200, the 464 torque is such that it takes a second to get 2nd gear. That's in a 4500lb LeSabre, doing the 1/8-mile in 9.5 with a 2.6-second 60-foot time (heavy car takes forever off the line).
