I have 71 cutlass s with a 350/th350. I just got a 1970 455 engine and would like to know if the th350 will hold up or do I need a th400.

 

It can be made to, but if it's stock it's not going to hold for long it you get on it at all.

 

For some field data,
I've been running a th350 for 2 race seasons behind my 455, no problems yet.
It's a stock 71 cutlass th350 trans, and the car runs 13.1

However F-85 on this board blew up 2 th350's with his 455 that runs 12.8.
If you're going to run one, run an old one. The 1975 and later ones don't seem to hold up as well.

 

If you are removing the 350 to install a 455 then just put in a TH 400 while you are at it. Better to be safe than sorry.

 

Thanks for the info guys. I think I will overhaul the th350 with a performance kit and try that. I dont drag only the occasional burn out.hopefully it will be ok if not I guess Ill need a 400.

 

You should be just fine if you're not running slicks.

 

It was 3 th350s

 

Totally agree with Jesse. If you're going to have to rebuild or beef up the 350, why not go with the tranny that Olds put behind almost all of it's 455s?