I know this is an old post but seemed the most relevant one to latch onto. I'm building a 66 with my 10 year old son.
I think I know my issue but appreciate help on verifying the solution. I have a 66 with I think an original C4 with the dipstick tube going into the case not the pan. PO had put in a 351w, casting of the block makes it a '79 I think D9AE-8015-ED is my best interpretation. Never yet fired since he put it in and I'm getting close to completion. It has a new flexplate of some wrong variety. Motor was locked up until I pulled the starter then could get it to spin freely with a breaker bar.
I verified the flywheel is warped by filming the inspection plate area while turning the motor. This flywheel has zero holes for any kind of torque converter drain, it is solid all the way around. It's at least 3/16 or 1/4" out of true as it spins and the torque converter has no nuts holding it to the flexplate, maybe the previous owner realized the issue and left that part undone...
So clearly I need to separate the tranny from the engine, pull flexplate and see what I'm looking at from a torque converter perspective, I'm assuming they all have drain plugs and this is the wrong flex plate.
Is it as simple as buying a 157 tooth 28oz imbalance flexplate for a 289 that would have come in this car? I have read that there is only one way to put this on but I have also read on this site that the counterweight needs to be 180 degrees opposite the weight on the balancer so one of those statements can't be true...
Any other things I should look out for, I'm doing this on my back with the car on jack stands, was going to disconnect driveshaft, bellhousing bolts, crossmember nuts, shift linkage, speedo, neutral safety wiring, AT kickdown, hoping I can unbolt cooling lines at the radiator and keep them attached to the tranny, (they were a pain to start those threads), position floor jack to support tranny (can I use a block of wood across the pan or do I need something u shaped to straddle the pan and contact the flange area left and right?) and scoot the darn thing back 6" or whatever in order to get to the flywheel bolts.
Thanks, this is my first post and know it is long, wanted to provide the best facts! Love this site.