Converting a 302 omc

[jchris1062]

I have a 1989 Four Winns 205 with a cracked block. Before I spend the bucks in the 302 ford I am looking to see what other options I have. I just got the boat so I am not for sure what kind of shape the drive is in. I would really like to use a 350 GM. I have a motor that came from another boat. My question is what will fit the drive I have in the boat today or what peices will I need to change? Or will i need to change the whole thing out and to what. I am new to I/O'S so I was hoping some of you may lead me down the correct path. Thanks.

[marshmat]

Hi, and welcome to boatdesign.net!

Since you mention OMC and you have a 20' boat, I'm guessing you have a Cobra drive unit. I'd start by checking what drive you have, and what kind of condition it's in. A worn-out Cobra is often not worth rebuilding and a refurbished Volvo or Mercruiser might be cheaper than fixing up the old drive. On the other hand, if the drive is good, it could conceivably give you another 10-20 years of service if you take care of it. So checking up on the drive (with the help of a good marine mechanic) would be my starting point.

How easy the motor swap would be depends on a few things, the drive being one of them. Another is the mounts- are their stringers solid? How hard would it be to adapt them to the new block? If you keep the drive, you might have a fun time getting the mounts to line up and you'd have to check on the gear ratio, which may be different with the 350. If you replace the drive, the Merc Alpha is perhaps the most common choice for this type of boat, but personally I prefer to see the much stronger Bravo-I with anything bigger than the basic small-block 350.