Snake,
Okay so i get what you're after. Your upgrading as you go. I did the same thing with my 70 360 Swinger. My 7 1/4 had 2.94s in it and lived just days behind my 360. Made hamburger out of it. The second 7 1/4 lived until I put an 8 3/4 in it, about 6 months. The difference was the way i drove it. Which is obvious. Okay enough on that, point being be nice to your rear or you'll lose your ***.
Torque converters are a mystery to some and to me as well. Until my local converter shop, Continental Torque Converters, gave me the cliff notes version on how TQs are rated. First off there is stall speed. Pretty obvious, you can get more stall from a converter by altering its fins. High end TQs have different fully welded fins based on your cars specs and desired stall. Cheap ones get bent, usually with a ball peen hammer (no joke!). Those are the ones to stay away from. Second is torque multiplication. There is a direct correlation between stall speed, converter diameter, and fin design. The cheaper converters have less torque multiplication and more slippage robbing you of precious hp.
For instance you need 2500 rpm of stall speed. Both converters in this comparison are quality converters built by the same shop. Converter "A" is a 11 inch unit. To get the desired stall speed it will have to sacrifice torque multiplication and the fins will have to lay almost flat to get it to slip at lower speeds. This converter would have say 1.2 times torque multiplication and will probably slip in high gear resulting in a few hundred more rpm at the end of the track. Converter "B" is a 10 inch. It will have to be on the tight side to get 2500 rpm stall. Its fins will be more straight up resulting in higher torque multiplication and less slippage. It would have a tq multiplication of say 2.2. You will see a few hundred RPM less at the end of the track. Obviously the 10 inch tq will be more expensive. Tqs are the difference between going to the track and have people say wow that car runs and you being disappointed at the time slips. The wrong tq converter can effectively make your car slow and disappointing. Dont skimp in this area and talk to a few good tq companies. You will be glad you did. I suffered through the wrong (cheap) converter for a few years chasing all kinds of different leads to try and find the key to getting my car to run. I changed the tq converter and it picked up 8(!) mph in the quarter.
I paid $400 for my 10 inch Converter from Continental and it stalls 3000 behind my 400hp 360 in a 3400# Dart with 4.56 gears. I recommend Continental since I have now been using them for years and their product is second to none and their customer service is excellent. Again this is just hte short version and anyone who knows more than I can correct or elaborate more if necessary. Good luck.
