My buddy has a 1956 Merc 312 he bought it from a guy who had it sitting in his front room since 2001. New, rebuilt everything. The engine is truly a work of art. I have added a picture of it to this post. We went to fire it up a couple of weeks ago the motor fired right up and in less than about 20 seconds it blew the seal around the oil filter adapter. He has one of those canister to skrew on oil filter adapter kits on it. We fixed the seal tryed it again and this time it put so much pressure into the filter it lifted the filter off the block. Both times oil pressure went from 0 to 80 psi in nothing flat. I got on the web found a few things and pulled the motor. We did find that the shop that built the motor did have the 2 shorter main cap bolts in the wrong spot, thought that might be it. Reinstalled the motor tryed firing it up today same thing blew oil out around adapter kit. We have checked to make sure the oil pressure relief valve was in right, and it is. Anyone have any thoughts. Can you cut a pressure relief valve spring down to drop your pressre?

Any ideas or thoughts would help. Thanks.

Ray