Ok to start with i had to purchase a set of motor mount adaptor plates from Butler performance in order to properly mount my late 70s 400 into a first gen subframe. I had to grind boss down on driver side so that the adaptor plate would lie flat against block ( the instructions that came with adaptor said i would probably have to do this) so after i bolted both plates down i set the engine back down and the driver side lines up perfect, however the passenger side is about a 1/2 inch or so. The tailshaft mounting holes line up perfect with the crossmember so im assuming the is in the correct position both front to back and side to side. I posted pictures below and as you can see the passenger side isnt lined up right. Kind of curious if anyone else has ran into this. The only thing i can think of is to drill some new holes into the adaptor plates but id like to hear what some you guys think first.
Loosen the mounting bolts and try to move them into position. If you lock everything down first things don't always line up perfect. Could just be crappy quality of the motor mounts. Pry it over into place if you have to. Once bolted down its not going anywhere.
I can line it up but then the tailshaft mounting holes are way off, would you agree that the enging should stay where its currently positioned and try to make adjustments to either the frame brackets and/or the motor mount adaptor plate? When i get home today I'll loosen the frame mount and see how much play ive got
I wound up having to redrill new holes in the adaptor on passenger side by about 5/8 of an inch. The trans mount from what i can tell are in correctly, im using the original crossmember that was in the car when i bought it with exception that it had a 350 chevy and a 4 speed muncie. (Wish id kept the 4 speed) The trans mount came from energy suspension which looked as though it could only go on one way. I just know if id mounted it the way it was there would of been no way to start a bolt through the xmember into the mounting holes. It was pretty obvious the tailshaft was shooting towards the driver side. Not sure what was to blame, frame mounts were aftermaket, the frame itself could be off a hair as someone mentioned.