I put in a rebuilt TH400 to replace the Powerglide in my 69, last summer. I ran the TH400 with the six cylinder for about three months and it actually gave that 175k mile engine more pep. I finally got the new 454 motor in and went to bolt up the flexplate to the converter tonight and the holes are about 1/2 inch to far out on the 454 flexplate. I think the converter is a TCI performance with the nuts welded to it. The motor is bolted up to the trans and the pins lined up no problem. Anyone ever run into this?

Yeah happen to me to. You need a 454 168 tooth flexplate with with dual bolt pattern for the larger and smaller converter. I just dropped the tranny
and replaced the flywheel. What happen is the 454 plate you used is for the larger converter and you have a performance one which uses smaller bolt pattern. Have fun replacing it.

you might have a dual pattern flywheel, if its not stock, try and spin the converter to the other set of holes
if you have to change the flywheel, TEST fit the converter to it in case you have to drill out the holes in the flywheel

Its a stock flexplate on the 454 so I don't think there is a second set of holes in it. Can I drill new holes with it on the motor? It might be easier to swap the converter, than to change the plate with the motor in the car.

I ordered a dual pattern flexplate that should be here in a few days. In the mean time, I can pull the motor (only the drivers side header is on, and motor mount bolts) or drop the trans.
What do you guys think is easier? My friends are saying to drop the trans.

If you have the room and a buddy helping, it's easier to do when it's out. However, you always run the risk of an accident happening...dent on the fender etc, but it's certainly do-able with the engine as is. Do you have double jointed fingers for the hard to reach bolts ? hee hee hee

John

Well, I managed to unbolt the trans from the motor, remove the crossmember and driveshaft. I moved the trans down and back enough to get a ratchet in there and take off the flexplate bolts no problem. However, I can't seem to pull the flexplate off the motor. Sprayed a little PB on it last night so I will give it another tug tonight. Any tricks to pulling this? After it's off I'm going to fling it as far as I can "mother" throw it !!