I have an 81 F250 with 400 against a freshly rebuilt C6 with a "heavy duty" (whatever that means) converter. I didn't notice before the rebuild whether it locked up or not but now there doesn't seem to be a torque converter lock up. Does the vintage C6 converter lockup? At what speed should it lockup if it does?Is a lockup converter available?
The C-6 never had a lockup converter from the factory. The new revised C-6 is the E40D. They actually share many parts. The E40D has the lock up converter, overdrive(4 speeds), and computer control going for it. The old C-6 only has dependability going for it :^)