91' OMC 4.3 to 02' 4.3 Vortec Block swap(maybe carb to fuel injection)

[mtconcreteco@gmail.com]

Hey there, A little back story... i have a 91 four winns with the 4.3 omc 2nd year i have owned it and it sat out a long time before i got it. The first year i was getting water in oil but boat ran pretty good. I pulled intake manifold and sure enough a couple hair line cracks in block...I also have another 88 or 89 omc 4.3 engine on a stand that i got for free from a friend that also has a massive crack in the block visible on the side of the block.... So now comes the fun part my plan is to rebuild the 4.3 that is out of the boat and what i have available to me is a complete 2002 4.3 engine from a blazer.

#1 with the three complete engines do i have everything i need to get a running boat again. I know i will have to swap things around and get new fuel pump and small stuff like that.
I believe i would have to use the 02 heads,oil pan and timing cover.(due to new bolt patterns being different) Not sure if i can put the older intake on that newer block. to get it running on the old carb system.( do i need to buy a newer marine intake for that year block.)

#2 Is it possible to switch over to fuel injection, if so what else would i be looking at. (minus all the electronics) Do i need a completely new intake or would i be able to use the 02 vortec stuff that is already coming with the complete 02 4.3 motor?

Has anyone completed a carb to fuel injection on one of these omc 4.3. Am i wasting my time even thinking of going that route.
Thanks for any help
I have done vehicle v6 v8 complete rebuilds before...but never a boat.

 

[Scott Danforth]

1. NO. your mixing gen 2 motor parts with gen 5.... other than GM and 4.3 liter displacment, there is nothing common between the two. not a thing. if you want to use the blazer long block, you will need a new marine circulating pump from 96 and newer, a new flywheel for a balance shaft motor, a new marine vortec intake manifold, and new accessory drive to fit the 96 and newer block

2. NO, not with what you have. however if you wanted to convert to a marine fuel injected motor, suggest you buy a complete marine fuel-injected long-tail from Mercruiser or VP and scrap everything OMC in your boat.

your wasting your time. trying to adapt automotive fuel injection to marine is like trying to contain a bomb after the fuse is lit. its not a question of if you will blow up, its only a matter of when

if you want a fuel injected motor, sell what you got, buy what you want.

 

[mtconcreteco@gmail.com]

Alright, Thanks for the info. Makes sense.

If I can get a 4.3 gm from 88-91.( looking around it sounds like in 92 they changed some things that's why i am thinking those years. Is that correct?)

Then would i be setup for the swap? What would i be looking at needing in that case?
I got the boat for free and do like the style. I really want to get it running nice and reliable again even if i decide to sell it after that.
Thanks for the feedback.

 

[Scott Danforth]

Yes, if you get a 1988-1991 long block, your stuff will transfer over

However you should be getting new exhaust manifolds anyway. As is the block is cracked, almost guaranteed the exhaust manifolds are cracked.

Not to mention, you boat most likely had block-busting bat-wing manifolds

Suggest the following:
1988-1991 block rebuilt, .030 over
1996 or newer vortec heads
Adjustable valve train conversion
new exhaust manifolds and elbows
Vortec 4 barrel intake
edelbrock 1409 carb with 1485 kit
Swap over your accessories. Electrics, etc
new coupler (because yours is probably close to toast)

Or buy a complete 1996 and newer mercruiser longtail and swap everything

 

[mtconcreteco@gmail.com]

Alright thanks for the info suggestion sounds pretty good and do-able
It actually does not have the bat wings but i would obviously check everything out pretty good before reusing anything.
If i went with a complete 96' merc would that match up with my omc outdrive?

 

[Scott Danforth]

If i went with a complete 96' merc would that match up with my omc outdrive?

No

if you went with a merc motor, go with a merc outdrive. by the time you stripped everything down and tried to fit it you would end up with a franken motor that would bite you.

while the base long block comes from GM, all the marine upfit parts make each motor unique to their brands. if you stripped it down that far, why pay more than you would for a simple rebuild.

BTW, if you want to change it would be cheaper for you to part out your OMC stuff and get a complete Merc or VP long-tail

if you want to go with a full 96 or newer long block and keep your OMC stuff, you would need to find an accessory drive for a 96 and up OMC, a 92 and up flywheel and appropriate OMC coupler, and OMC exhaust manifolds

 

[mtconcreteco@gmail.com]

yea I am going to just search out the proper block to replace what i have broken and get the boat going how it was build originally, then maybe down the road i will upgrade to a newer boat. Thanks for your help. Those blocks are not very pricey but finding the older years seems to be getting harder and harder in my area.

 

[Scott Danforth]

use car-part.com if you want to search salvage yards