89 4.3 mercruiser motor swap

im going to pull my 4.3 just found out the blocks cracked and low compression.so my question is im just going to buy one from a truck so what year range do i need to stay for everything to bolt right up.thanks

Re: 89 4.3 mercruiser motor swap

There are a lot of marine-specific things. The blocks are the same, but there are details like head gasket composition, freeze plugs, block drains, cam specs, etc that are not the same as a pickup truck has. The heads also may be a different and high performance casting compared to whats on a truck. If you're handy with a motor, you can install all these things on a truck motor, but you're still working with a used unknown engine.

Another little trick with the 4.3 is that there are two of them, and not all of the parts are perfectly interchangable. I'm not sure the exact specifics, but there is a difference between the Tonawanda engines and the Romulus engines. I think the difference may be specific to the main bearing caps, but you're going to want to verify this.

Re: 89 4.3 mercruiser motor swap

speaking from experience (someone how's actually done it, not just generalizations)

#1. If you are using a vortec 4.3, the truck cam is spot on with the marine cam.
#2. If you have a heat exchanger, you can keep the truck head gaskets and the truck water pump, and even the truck frost plugs.


If you do NOT have a heat exchanger, than you are going to have to change you're water pump, and head gaskets and frost plugs over to marine, or install a heat exchanger.

Try to source a 200 HP 4.3 (like from an AWD astro van, or a 4x4 s-10, they're you're best bet, they will make about 230 in a boat if setup properly)


The 2WD 4.3's were only spec'ed for 180 HP.