Omc/chevy 4.3?

twofourdee · Dec 21, 2009

Just wondering if the omc and chevy 4.3 L engines are the same because i have a 89 four winns with a cracked block and i have a 4.3 chevy motor i was thinking about replaceing it with.. The omc motor is carbed and the one that would be out of a vehicle i have is f/i so if they were the same would i just be able to swap heads and manifolds and what not or??? Thanks in advance any help or suggestions are much appreciated

Bifflefan · Dec 21, 2009

Re: Omc/chevy 4.3?

twofourdee said:
Just wondering if the omc and chevy 4.3 L engines are the same because i have a 89 four winns with a cracked block and i have a 4.3 chevy motor i was thinking about replaceing it with.. The omc motor is carbed and the one that would be out of a vehicle i have is f/i so if they were the same would i just be able to swap heads and manifolds and what not or??? Thanks in advance any help or suggestions are much appreciated

Id have to say i doubt it unless the blocks are the same year or at least the same style (rear main and such). The cams will not be the same.
If its a comparable block then its a good donor block.

zbnutcase · Dec 21, 2009

Re: Omc/chevy 4.3?

All '86 and later 4.3's (meaning most all of them) use the one piece rear main seal; 0nly '85 Astro vans used a 2pc seal 4.3. Depending on the year of donor eng, it may or may not have provisions for the mechanical fuel pump your '89 has. You will need to swap cams, install brass core plugs, and I highly recommend marine head gaskets be installed; a lot of work but doable. However, considering the loads marine engines face, if said donor has over 20-30K mi on it, I would rebuild it first. 'nutcase

cr2k · Dec 22, 2009

Re: Omc/chevy 4.3?

Just curious, why you would rebuild with only 20-30K? These engines should be good for 150K. BTW 100K = about 3000+ hours.

Anyway...Nutcase is right about cam swap. Other consideration would be compression ratio of auto engine (smogged) and marine engine, (not smogged, big carburetor, etc.)

Bare blocks should be same-o same-o.

Marine engines have different; circulation pumps, cams, core plugs, any gaskets with metal will be stainless, not to mention spark sealed electrical and electronic components.

twofourdee · Dec 22, 2009

Re: Omc/chevy 4.3?

wow ok i was hopeing it wouldnt be that much work lol the donar engine would be out of my 92 astro and it has over 200,000 on it so i guess i would just be better off trying to find a good used marine motor then huh... Thanks for the quickly responses guys any recomendations on what would be best and easyiest to do also inexspensive?

Gary H NC · Dec 22, 2009

Re: Omc/chevy 4.3?

A long block from Rapid-O marine..
http://www.rapidomarine.com/default.aspx?p=/engines/default.aspx

twofourdee · Feb 5, 2010

Re: Omc/chevy 4.3?

so ive decided that i will most likely be going with the long block from rapido marine... what all exactly will need to be done for the swap? are all the parts that are going to need to be swaped external parts and is there anything i should know of before trying to tackle this myself? im expirenced with motors and what not but dont know to much along the marine line this is my first i/o.. are there any diy's on here for this particular situation? Thanks for any help guys i may need as much as i can get lol

Bondo · Feb 5, 2010

Re: Omc/chevy 4.3?

are all the parts that are going to need to be swaped external parts and is there anything i should know of before trying to tackle this myself?

Ayuh,... It's a typical Long Block Swap,... All the externals from the old motor are reused...

Gary H NC · Feb 5, 2010

Re: Omc/chevy 4.3?

I would also suggest new tins for the engine with several good coats of Rustoleum. Those oil pans and timing chain covers are known to rust.
Also remove the front motor mounts by the lag bolts and not the fine thread adjusting nuts.

http://bpi.ebasicpower.com/catalog/index.php?CAT=&PAGE=245

Fishermark · Feb 5, 2010

Re: Omc/chevy 4.3?

twofourdee said:
i have a 89 four winns with a cracked block

Is this a "new to you" boat - or one you have had for awhile? If this is a boat you purchased with a bad engine, you might want to rethink buying a rebuilt engine to put into it.

If you are already familiar with the boat and outdrive and really like it... then that's a different story.

Just something to consider before sinking a lot of money into it.

twofourdee · Feb 9, 2010

Re: Omc/chevy 4.3?

i think ill probably take it some where to get it done just to make sure its all done right and warrenty... got an estimate for just under $3000 for a long block and labor.. Good?? And ive had the boat for about 2 years just totally forgot about winterizeing it before last winter..

Omc/chevy 4.3?

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