PCM 350 Cracked Block

So I normally run 6 gallons of RV antifreeze through my PCM 350 engine before winter and it's fine. This year I only had 2 gallons. That's not enough.

I charged up the battery and backed it into the water and it started right up and after 2 or 3 minutes was idling nice. Then I noticed the water pissing out the side of the block. I talked to some friends who are welders and they said they could weld it up for me. A week later I went in to remove the strainer basket and a couple of spark plugs to prep it for welding and noticed the bilge full of milky oil. Which leads me to believe that it's not just a crack in the exterior water jacket part of the block, but something internal. The dipstick looks kinda milky also.

It's a very old boat that I paid $3K for 12 years ago (put about $2K into the interior/floor). So I don't want to sink a lot of money into it. I am trying to find a used marine engine. Have seen a couple on Craigslist for $1K-$1200 but they sold quickly. I have a guy that would rebuild something for me, but I have too many questions.

First of all if you use a 4 bolt street block, it is designed to rotate opposite direction right? My prop spins RH. If a guy were to take a street or even a marine block and rebuild it with my carb and the other bolt-ons, would simply using my RH cam and distributor make it run RH?

Could I take a running used GM 350 and just swap out my bolt-ons like water pump, alternator, carb and then just change the cam and distributor?

What about the transmission end? Will any block just bolt up to the transmission?

Any/all advice would be appreciated.

You would have to strip everything. Replace the crank with your rev rot crank, and go from there. The rods, pistons, are going to be the same but the cranks oil seal journal is different and the oil passagways were clearanced and polished opposite of regular rotation. The bearing and seals are the same but if theu were run in one direction not good to install them opposite.

A block is a block. 2 bolt vrs. 4 bolt does not matter. 2 bolt is plenty strong for your purpose and cheaper. If your buddy is reasonable then I would get a block and let him swap out the rotatable assy. If you number your lifters then you can reuse them also. That would give you a fresh engine for many hours to come. Minimal $$ and you will be ready to go. Several of us have spare blocks on hand but when you guys list your location as "US" then it's a guess as to ship or pickup. Good luck and keep us posted.

8122pbrainard wrote: Duane,Considering the cracked block, I'd say we could narrow the location down to about 40% of the states!!

So true Pete. These guys make it hard to help them though.

lucenut wrote: Could I take a running used GM 350 and just swap out my bolt-ons like water pump, alternator, carb and then just change the cam and distributor?

No so simple, piston pins are offset on the chevy, so pistons would have to be turned 180 degrees else you will hear lots of piston slap. May require pushing the wrist pins, and may not be as simple as swapping banks with pairs of rods.