I have two conflicting opinions here and i need some input. I swapped out my old 305 for a 350 at a shop that only swaps engines. I was driving the other day and heard a noise so i swing by and took the mechanic for a ride and he says that my y-pipe is hitting the body while driving. So i take it to my exhaust guy. Well my exhaust guy calls me and says that my motor mounts are sagging causing the passenger side header to lie against the frame, so, i call the shop and tell them this. He asks if i was charged for them and i state the fact that i dont know i will have to check. My exhaust guy calls me up again and says he had another guy look at it and they both agree that anyone in their right mind would change out the motor mounts on a 17 year old car when swapping in an engine, especially if it was a 305 to 350 swap. He says if the mounts were not sagging than the exhaust headers would have enough clearance and there would not be any contact with the body. I just want to get as many opinions from anybody who is a mechanic or has experienced an engine swap so when i go in to the shop tomorrow to get them replaced i either, pay them for the work or, dont pay them because this is their mistake to begin with.

 

Stock mounts sag. But, unless they are so bad that they are falling apart, a shop probably won't replace them unless you specifically tell them to.

I can't imagine the exhaust hitting the body due to sagging mounts. Chassis, yes. Body, no.