Anyone here know what bolts are specified for the engine mount to firewall for a 1952 Cessna 170B with the Avcon 180 HP engine conversion. I couldn't find any mention of it in the plans. Thanks Gary

I think you want AN6-33A for the lowers, and AN6-22A for the uppers. The length is critical so it doesn't get bottomed out. The drawing shows two washers under the bolt head for the lowers.

I ordered these lengths for my Del Aire STC and they worked fine.

You need to decide if you want to keep the rubbers or go to seaplane solid aluminum bushings. The washer on the inside (0550153-1) under the nut is hardened I think, so don't swap them out.

FWIW Gary I would go with the seaplane bushings.
I swapped out the rubber bushings on my 180 a year or two ago,
and the solid bushings seemed to smooth things out a bit.
They will also last forever, unlike the rubbers.