3.8L to 4.3L OMC stringer engine swap

[fishforfun2]

I bought a boat with a 3.8L OMC/stringer outdrive and I had to pull it to replace a leaking oil pan.I found a 1990 4.3L vortec OMC complete w/manifolds etc and want to know if it will match up with my 1982 stringer outdrive?Thanks for info,Dale

 

[Howard Sterndrive]

Re: 3.8L to 4.3L OMC stringer engine swap

nope.
There is no coupler for an OMC stringer drive that will mate to the later 4.3, or any chevy with 1 pc rear main seal pattern crank.
Need to stick to pre-1987 engines.

 

[fishforfun2]

Re: 3.8L to 4.3L OMC stringer engine swap

nope.
There is no coupler for an OMC stringer drive that will mate to the later 4.3, or any chevy with 1 pc rear main seal pattern crank.
Need to stick to pre-1987 engines.

Bummer,it seemed like a good idea but if it can't happen easy I don't want to bother with it.He also has a cobra unit complete and I was looking at that but my transum is too thin for it.

 

[Howard Sterndrive]

Re: 3.8L to 4.3L OMC stringer engine swap

engine swap seems like a drastic way to fix an oil pan leak...
must be more wrong

 

[fishforfun2]

Re: 3.8L to 4.3L OMC stringer engine swap

The guy I bought it from got tired of paying storage on it since he ran it out of oil at the dock and heard noise coming from engine.Its been sitting on the trailer in San Diego Ca for 8 months and wasn't cleaned out.It was a make me an offer deal on an 82 Criiser 22' walk around cuddy with a custom T top/radar arch and OK trailer.He didn't know what happened to lose oil but when I pulled the motor its leaking around drain/dipstick on bottom of pan.
Other issues are that I couldn't separate the bellhousing from motor because the coupler is stuck to the shaft so I had to pull intermediate section out too.Then I checked the oil in outdrive and its got water/oil in it so it needs a seal somewhere?
I already bought a complete 1983 OMC 3.8/stringer outdrive with 391 hours out of a lake boat thats in fine shape and running but its only got a 2 barrel carb so instead of swapping manifolds and carbs from boat motor I saw the 4.3L and cobra OD for $800 complete and wanted to go that route instead.Too Bad its got more HP and only 2 barrel in the vortec.

 

[cr2k]

Re: 3.8L to 4.3L OMC stringer engine swap

Well the thickness of the transom should not be an issue to swap to the cobra as you will have to rebuild the transom and fill in that big hole from the stringer. Just beef it up.

 

[Howard Sterndrive]

Re: 3.8L to 4.3L OMC stringer engine swap

Too Bad its got more HP and only 2 barrel in the vortec.

I don't think you'd notice the extra 5HP


1983 800 stringer to 1990 Cobra....not worth the conversion- unless SEI converting the Cobra hardware too, but you'd have to redo the boat's steering as well as other headaches.
I prefer the last series of full mech stringers to Cobras but that's just an opinion ... others like the Cobras - it's all obsolete stuff.

if the boat is worth repowering / modifying transom etc - go Mercruiser 4.3/Alpha 1
...or V8 - that's a big boat

where did you measure the transom? I'm surprised it doesn't have the thickness required. Most 1980's boats were all built to std. thickness.

 

[fishforfun2]

Re: 3.8L to 4.3L OMC stringer engine swap

I thought its was a 20 HP upgrade?I removed the motor and intermediate housing because the coupler is stuck,I tried hyd jacks on both sides of motor mounts to bell housing but still wouldn't pop,only about 3/8" gap around it.I measured inside the cut out and its about 1 1/4" thick but I was told I needed 1 3/5" min.
It already has power steering setup but I'm trying to just do it quick and easy not spend too much time rebuilding transum.I just want to put a good motor in it and go but its never that easy.
Can I swap flywheel/coupler from 3.8 to 4.3?The 4.3 has a closed cooling system too.
Thanks,Dale

 

[Howard Sterndrive]

Re: 3.8L to 4.3L OMC stringer engine swap

A 1990 4.3 2 BBL makes the same power as a 1983 3.8 4V

Can I swap flywheel/coupler from 3.8 to 4.3?

no., not to a 1990 4.3

 

[Howard Sterndrive]

Re: 3.8L to 4.3L OMC stringer engine swap

I just want to put a good motor in it and go but its never that easy.

I already bought a complete 1983 OMC 3.8/stringer outdrive with 391 hours out of a lake boat thats in fine shape and running

am I missing something?

 

[fishforfun2]

Re: 3.8L to 4.3L OMC stringer engine swap

I bought the 3.8 with outdrive and then found the 4.3 that the guy said will go right in to replace the original 3.8.Now I'm finding out that the 4.3 won't work so I will use the 3.8 from the lake boat and get rid of the original motor/stringer