302 Swap

[PARick]

I am a new boater, and I just bought a Four Winns, with a cracked block, and I was wondering if I could use a regular(Automotive) 302 block??? All other parts, intake, exhaust, etc., have been magnafluxed, ans are o.k.! Are all other parts compatable, pistons, rings, bearings, etc.???? Thank You for the help!!!!

 

[rattana]

Re: 302 Swap

It depends, if you have a closed cooling system you can get away with an automotive block if you use a marine carb, starter, distributor, and alternator, etc. With raw water cooling you need S.S. head gaskets, brass core plugs and marine water pump to name a few things.

 

[Boomyal]

Re: 302 Swap

you may not just be able to swap pistons and rings, you should have a machine shop check bore measurements. You didn't say how old the 4winns motor is. At minimum you probably should re-ring and hone the replacement block. Any automotive machine shop should know all other compatibility issues.

 

[PARick]

Re: 302 Swap

I apologize!!! The boat and motor, are 1996. I have the complete engine, but the block is cracked into the cylinder wall! I have rebuilt many automotive engines, but I have NO experience with boat engines!!!I believe it is an open cooling system, as there is no radiator, and the discharge is through the prop. I still don't understand if I can use an automotive block. I WILL put new pistons, rings, bearing, etc., in, but I will be using the intake, exhaust, and all other external components. Once Again, Thank You, and I apologize for my lack of knowledge!!

 

[Bondo]

Re: 302 Swap

I still don't understand if I can use an automotive block.

Yes........<br />No Problem........

 

[fastimz]

Re: 302 Swap

Yes, you can use an automotive block..The blocks are the same. You will need to use a marine gasket set (ss head gaskets), a marine cam and other bolt-ons. Make sure that the block has brass freeze plugs also.

 

[f_inscreenname]

Re: 302 Swap

What is up with this SS head gaskets on many posts. I know it is recommended but I have used Fel Pro for years and never had a problem.<br />As for the using a auto motor. If it is around the same year, like others said a long block is a long block(except for the brass freeze plugs). Think about it GM is not going to make special blocks for just marine motors. There just isn't enough money in it for them. Block, pistons, crank, rods, oil pump, intake, heads (all parts valves, spring etc) are all identical to auto. Oil pan may be a little different. You said you are going to rebuild and you are going to use the old cam? Why? Cams are cheap and do wear out even if you haven't noticed the lost HP. Do yourself a favor and replace it and the lifters. I just installed a duel plane cam in my boat from Crane (there Powermax line). Best thing I ever did to it and I have done a lot. It works by opening the exhaust valve more and for a longer time. It is made for exhaust restricted motors and marine exhaust systems are very restrictive. When I bought it I got the same intake lift specs so it didn't change the top end but it performs so much better. Great idle (unexpected for as radical as the cam I use) , lots of torque throughout the throttle, and a noticeable gas savings. Sacrificing performance for gas mileage is not me but this cam gives you the best of both worlds. Get this, its only about $50.00more then a run of the mill cam. Get one you will not be sorry!

 

[tylerin]

Re: 302 Swap

Think about it GM is not going to make special blocks for just marine motors.

Four bolt main

 

[f_inscreenname]

Re: 302 Swap

I thought the four bolt was made for truck/heavy duty use. As for Chrysler and Ford I don't think they even offer a four bolt block. There is no money in boat motors and the warranty issues is enough to make anyone stop building them. Two reasons Chrysler (IMHO the toughest marine motors made) got out many years ago.