Originally Posted by 77pontolds
We still can't get the engine to bolt into the body. I removed a 403 Olds, and got new rubber mounts to fit a Pontiac 400. I got the engine brackets from a 400 Pontiac engine that was in a 78 Bonneville. We are trying to install the 400 in a 1977 Firebird formula. We have tried various bolt paterns on the crossmember, to no avail.. The 400 is a 1971 block. We've been at this for four days now, and have pulled the engine at least 4 times. I have never had this much trouble swapping engines before, but I'm determined to make it work!! HELP Please. Thanks, Uncle Rich
I had a Pontiac 455 in a '81 Camaro. I used all stock parts from the B-body wagon the engine came from and it fit. I don't recall details on the holes, though. IIRC I welded the motor mounts to the crossmember and left it like that.
What you can do is mount the rubber mounts to the engine brackets using the through bolts an nuts but not tightening them. Then set the engine down onto the crossmember and see if anything lines up. If nothing does, you can mark and drill new holes. I have spot welded them directly to the crossmember, then remove the through bolts, pull the engine back out for drilling/bolting (did this when I put a 455 into a 4X4 Chevy Blazer).
If you do this you have to be sure the engine is square and not sitting too high or low, etc. due to any differences in the B-car brackets vs. the F-car brackets.