I'm trying to install a 454 into a 71 Chevelle that had a 307 in it originally. The problem that I am having is that I can't get both mount holes to line up. I have install many motors and never have had this much trouble. I'm sure the motor mounts are correct, but I had to bend the motor mounts just to make it fit over the frame mounts. I am wondering of the frame mounts need to be change out. I tried everything, it seems to be about a quarter inch off. I have one side pinned, but the other side just won't go. Thanks to all who respond.

The 307 frame mounts are wider and slightly taller than the 350/BB frame mounts..so you can either bolt the 307 engine mounts to the 454 and use your existing frame mounts, or swap out the frame mounts for 350/BB ones and keep the mounts you currently have on your 454. The engine will end up in the same position either way. Because you had to pry the engine mounts open to fit over the frame mounts I know you have 350/BB engine mounts on the 454.

Hey Drptop,
Thanks for the response, I don't have the motor mounts from the 307. I was wondering, is that something I can go down to the local parts store (NAPA) and pick up?

Yep !!

Hey Guys,
Just got back from vacation! I changed out the 454 motor mounts for the 307 motor mounts and I couldn't believe how easily everything fell into place. Thanks again.