Are the BOP TH350 and TH400 torque converters interchangeable? When I was a kid, IIRC my dad swapped the stock TH400 converter with a TH350 convertor on his 70 Monte Carlo SS. Seemed to give it a few hundred RPM higher stall. I've read a few times here that the heavier the car and the bigger the motor the higher the stall speed of the converter. If I swapped in a TH350 stall converter into my 69 Electra's TH400 would this be the case? I'm also liking the idea of possibly going with the whole TH350 setup as the it seems the 1 & 2 gears are a bit lower. Might make a nice combo with the more common 2.93 posi I'll likely end up with. Thanks in advance.
Thanks for the responses guys. Any ideas on which motor flywheels had the dual bolt patterns? Would going down this road be worth my while? I may have a shot at a 65 ST400 switch pitch, but IIRC I would have to swap the converter and front pump into a TH400 housing to bolt up to my 430. Is this a difficult swap/shift kit rebuild? Hell I've got time and a service manual - I may not be skilled but I'm at least dangerous.
You have to look at the flexplate. It will be obvious if it has the two different bolt circles for the different converters. The TA Performance flexplate repros have the dual bolt circle holes.(see picture) If you are familiar with transmissions, switching the front SP pump shouldn't be a problem, but there is a hole in the case that has to be plugged. I would leave it to a trans rebuilder.
