I have a 1966 Pontiac Beaumont. Old engine was a straight 6. I am using a different bell housing, different pressure plate/clutch (12in), different stud (adjustable), different throwout bearing (adjustable) and a v8, but I am still using the same clutch fork. I seem to be having problems with the clutch releasing the disk. It seems to not release, or not grab at times. The clutch disk is facing the pressure plate correctly. Do I need a different clutch fork?

I tried increasing the pushrod length, and adjusting the stud with different results but no significant difference.