replacing 3.8 with ? on OMC stringer

greentahoe

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Jul 30, 2005
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My 1984 stringer engine just bit the dust for the last time. I have the 3.8 v-6 in a 23' Proline walkaround. The 3.8 is rated at 185 hp with the 4bbl carb, and is fast enough for me. I want to get into something that has better availability when looking for parts, such as manifolds etc. I'm thinking of going to a 4.3. Will the intermediate housing bolt up to the 4.3? I'd like to use my 4 bbl Rochester on the new motor, any reason I can't do it?
I'll have more questions later I'm sure, but this is a start.
Thanks.
 

Bondo

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Re: replacing 3.8 with ? on OMC stringer

Will the intermediate housing bolt up to the 4.3?

Ayuh,......... Everything should just Bolt Up,........

Provided you don't run into Vintage Issues..............
 

whywhyzed

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Re: replacing 3.8 with ? on OMC stringer

4.3 manifolds and 3.8 manifolds are the same manifolds- I can't think of any parts for a 4.3 that would be more available than for a 3.8
 

KaGee

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Re: replacing 3.8 with ? on OMC stringer

For starters, your Exhaust manifolds won't bolt up due to the larger valve covers on the 4.3L.
Not sure the intake is re-usable.
None of the tin will cross over other than the timing cover.

Not sure if the distributor can be re-used.

So, If you can come up with a complete 4.3L and willing to retrofit a new exhaust, you can do it. the bellhousing will bolt up with no problems.
 

KaGee

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Re: replacing 3.8 with ? on OMC stringer

4.3 manifolds and 3.8 manifolds are the same manifolds-

Mike, The 4.3's valve cover is taller. The 3.8 manifolds will not clear them. That why you have those goofy batwings on all of the early 4.3's
 

greentahoe

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Re: replacing 3.8 with ? on OMC stringer

Thanks for the info. I think I've found a buildable block 4.3, mid 90's vintage from a truck. Hope to get into it pretty soon.
 

MikDee

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Re: replacing 3.8 with ? on OMC stringer

Mike, The 4.3's valve cover is taller. The 3.8 manifolds will not clear them. That why you have those goofy batwings on all of the early 4.3's

Those suckers are ugly, expensive, & hard to find, had 2-OMC Cobra 4.3V6's in my last boat, that's why I sold it, one is more then enough to deal with.
 

whywhyzed

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Re: replacing 3.8 with ? on OMC stringer

Thanks for the info. I think I've found a buildable block 4.3, mid 90's vintage from a truck. Hope to get into it pretty soon.
Won't work - the bolt pattern rear of the crank is different - no stringer compatible coupler was ever made for the newer chev cranks - gotta stay pre 1987 when you have a stringer drive.
Also your marine distributor will not work on a 4.3.
Stay 3.8 - they are as good as a 4.3 in a boat as far as I'm concerned.
What I was meaning b4 about manifolds is that any manifold that would bolt to a 4.3 will bolt to the 3.8 - selectrim means you need to go with OSCO as Kagee did.
One side of the 3.8 manifolds is still in stock with OMC - the other side is backordered - doesn't actually say NLA
3.8's make vy. good power with a 4 bbl - my boat runs 52 mph with it's 3.8
 

greentahoe

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Re: replacing 3.8 with ? on OMC stringer

And the plot thickens... The reasons for going to a 4.3 would be that my old 3.8 is a jinx. I've had it for about 8 years and it continues to have major breakdowns on a regular basis. I won't go into the long list, but it's had everything changed that can be changed or rebuilt at least twice in that time, and I've never had it in the water more than three times in any year. The cast iron block is getting thin in places, the crank has been turned twice, the distributor was worn out and the only place in the world I could find a replacement was on Ebay, etc, etc, etc. I really sick of the thought of putting any more money and sweat into an engine that I won't have any confidence in when I'm done. I recently had to change the upper gearcase in the 800 outdrive and now that works very well. It's now a matter of either replacing the engine or selling the boat with a bad engine in it and buying something smaller that I might actually get a chance to use more than twice a year. The tough part is that I really like the boat. It has a great ride and enough room for all my fishing junk. I fish salt water with it and I hate to give it up, but I've lost interest in rebuilding the 3.8. I don't think that the block I have is actually worth rebuilding at this point. It doesn't have any cracks, but I already have three helicoils in it to thread the headbolts in. My manifolds are fine, OMC at that, and everything else works. I installed a fresh water cooling system in it about four years ago, and that works very well too. Maybe if I could find a decent 3.8 car engine and start swapping parts that would be the way to go. Having had one original head rust through a while back makes me leery of picking up an old saltwater engine, and that's what I'm likely to find around here.
Don't know where this is headed, but I certainly appreciate everyone's input.
Thanks!
 

whywhyzed

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Re: replacing 3.8 with ? on OMC stringer

Maybe if I could find a decent 3.8 car engine and start swapping parts that would be the way to go.
yep - 80-84 Monte carlo, El camino, and others, add Edelbrock 2112 cam and brass core plugs and you have the same thing as OMC, VP and Mercruiser used.

If you're going to change engines in a 23' foot boat - I would go 350 V8 and regear the upper.
 
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