Hi all,

My son's been given a 1980's fishing boat ("Free boat" - the most costly phrase in the English language) with a previously seized Chevy 350 engine driving an OMC Sterndrive.

The engines obviously got to go, but the wet exhausts etc seem to be reusable. Our local junkyard has any number of vans and trucks with 350's in them, mostly badged as Vortec 5.7l

What do we need to look at in regards to switching a 'regular' 350 with a Vortec 350?

Until we pull the old engine we won't know what the bolt pattern on the connection between engine and Sterndrive is, but anything else we need to look out for?

 

Bolt patterns on Gen I and Gen II SBC are all the same, my suggestion is to find a running engine, if it is a vortec swap the heads and intake with what is in the boat. A vortec motor will require a "computer" and a lot more wiring than what is in the boat, which I am assuming has a carb because of its age. Another way to skin the cat would be if the replacement is a vortec change the intake with an aftermarket carb intake, this would cost a bit more than just swapping the old heads and intake over but the vortec heads are better power wise. Also you will need to keep the old distributor as the vortec distributor is also "computer" controlled. Also thinking about this, (never thought about going backwards on a vortec) the vortec has a roller cam, there will be no pushrod guide plates in the old heads so to make it work right you might have to change the cam to a flat tappet style to make it all work together, so going aftermarket intake may be the cheaper/easier route.

 

Agreed with bear .since you said junk yard thrifty is the key and boat . Recommend the 96 up real vortec 880block ,take all the pulleys brackets and appropriate flywheel look for dimple holes on rear driver side of casting # by oil pressure sensor usually indicates 4bolt not guaranteed but usually is. The 96 up heads flow better rev higher ,good to have in a boat consider slightly stonger valve springs to your desired rpm limit and of course a rev limiter for those moments of out water chop and over zealous throttle. You'll be glad you did. Aftermarket carb intake , new hei distributor e _ay, depending on how good or rebuilding new any where from 500 to 2.5k $