I have a 1982 440 LTD. Everything is great except when I back off on the throttle and go at a steady speed, it feels like the secondary clutch shifts into overdrive and it pulls the RPM's down to about 5000, then when I try to accelerate, it takes a couple of seconds for the RPM's to come back up to regain performance.
I tightened the secondary spring from 150 degrees to 180 degrees and it helped a little. I have gone threw both clutches and cleaned them. I am starting to think the problem is with the main clutch. Any suggestions?