Firewall and engine mount holes don’t line up

The instructions say the engine mount holes in the firewall may not match up with the engine mount, but to use the engine mount as a guide to enlarge the holes to 3/8”. When I did this the bit centered itself on the pre punched hole and pulled the engine mount over the hole even with the mount bolted in place at the first hole. So the engine mount holes still don’t line up with the holes in the firewall. I was able to pull the engine mount enough by hand (no pusher clamps) to get all 4 bolts installed. Is this acceptable? If not, what’s the fix? Thanks

Not an RV, but I helped an old boss install an R-1340 on a Norseman. We used ratchet straps to pull, squeeze and twist the engine mount to line up with the holes. Wasn't pretty, but if that old thing has been flying since the 40s, I'm sure it can't be too bad on other airplanes. I'm sure the RV experts will chime in here soon with some better advice.

For the next person, holes can be realigned with a circular or "chainsaw" file. Go slow and take your time, one can get a hole easily moved in any direction. Probably best to finish with the file slightly undersize and finish it off with the proper sized drill bit to ensure it's a proper circle.

Yes it’s acceptable. A by-product of welding is loss of tolerances.