4.3 Mercruiser Swap for 4.3 Truck motor (One Stop Shopping Thread)

[DrCox]

So I have been combing over the forums for a few days now gathering up all of the knowledge about the subject of replacing a 4.3 Mercruiser with a 4.3 truck engine from S10 or similar. Since there is no sticky yet let me first start out with a request that either part of this thread be made into a sticky or someone that is better at writing make a sticky for this subject :joyous:

**DISCLAIMER** I found ALL of this information digging through Iboats forums and in no way claim that any of this information is mine. I thank everyone for the time they spent getting this information out to us even though I dont mention everyone by name.

I will post my actual question in the next post on this thread...

1998 Mercruiser swap for 1995 Truck 4.3
http://forums.iboats.com/mercruiser-i-o-inboard-engines-outdrives/chevy-4-3-conversion-612671.html

1992 Mercruiser to 2000 S-10 4.3
http://forums.iboats.com/mercruiser...k-motor-marine-need-advise-please-611695.html

Questions about 4.3 Auto and Marine Heads
http://forums.iboats.com/mercruiser.../true-false-about-4-3-truck-heads-589785.html

Awesome rundown of Chevy V6 engines
Chevy V6 229,262,4.3 v-6 Engine Info & Performance

Questions about Marine vs. Automotive gaskets
http://forums.iboats.com/mercruiser-i-o-inboard-engines-outdrives/engine-spares-585741.html

General Discussion of 4.3 Mercruiser parts on GM truck block
http://forums.iboats.com/mercruiser...-engine-parts-fit-chevy-4-3-block-474156.html

 

[DrCox]

Re: 4.3 Mercruiser Swap for 4.3 Truck motor (One Stop Shopping Thread)

So, Here is what I have going on:

1995 SeaRay 185 with 4.3 Mercruiser that was not winterized. So far my tear-down has revealed 2 cracked exhaust manifolds (already purchased 2 new ones) and a port cracked head. I see that the core plug is bulging on the starboard side as well which makes me skeptical on whether or not this block will be internally sound. The decision has been made to error on the side of caution and buy a new motor.

With budget in mind I have located a few motors that seem to be a good match for what I am doing. In general I want to make sure I address all of the concerns with swapping a marine with a truck motor.

Things that need to be swapped or modified:
1) Need to change out stock Cast (freeze) plugs to brass plugs (if not already brass)
2) Need electric Fuel Pump, Mercruiser blocks are drilled for mechanical pump, not Truck block
3) Intake manifold may need to be swapped (verify bolt pattern)
4) Swap Starter and Alternator from original block
5) New Head and Intake Manifold Gaskets (marine for intake, composite for heads might work as long as it contains stainless steel)

Based on the assumed complexity of this swap I am pretty sure there are more than 5 things that I need to be aware of. I was hoping I could get people to contribute to this list. I did not add Block identification numbers yet, but if that matters even though I am using the entire truck long block please let me know. Hopefully we can get a good comprehensive list that will not only help me and others, but maybe one day become a sticky so we don't all have to search this deep

Thanks in advance

-DrCox

 

[carribbean soul]

Re: 4.3 Mercruiser Swap for 4.3 Truck motor (One Stop Shopping Thread)

This works with any engine I replaced a chevy 350 marine block with a junk yard take out for $400 moved all marine accessory's over to the new block changed out the head gaskets with marine bronze freeze plugs. I was back on the water in one weekend!

 

[tpenfield]

Re: 4.3 Mercruiser Swap for 4.3 Truck motor (One Stop Shopping Thread)

+1 ^^^

the only thing that I would add is carburetor/fuel system and distributor/ignition system to be brought over from the Mercruiser block. Maybe the cam shaft, if you like and if possible.

 

[DrCox]

Re: 4.3 Mercruiser Swap for 4.3 Truck motor (One Stop Shopping Thread)

Ted,

I am probably going to skip the camshaft since most of what I have ready says that the 4.3 truck has enough torque to be ok. Plus, I would like to avoid as much internal work as possible