OMC Cobra Engine swap

[Milenko]

Hey all,

I have an 88 Bayliner Capri with an OMC 2.3L I/O. The engine is next to dead and I'd like to upgrade it to a larger engine. What is involved in swapping this engine to a 4.3L V6 or a 5.0L V8?

I know that I'll need to find exhaust manifolds for the new engine and the new engine (duh), but I'm not sure what else to look for. I also have read in the repair manual that you're not supposed to use the Cobra outdrive with the 5.0L engine and instead are supposed to use the King Cobra outdrive. I assume that it's either geared differently or is just has beefier gears/shafts/bearings/etc to handle the extra HP.

I have lots of experience with (car) engines and I have a mechanic friend who has volunteered his garage for the project. All I need now is to figure out for sure exactly what I'll need.

Also, if anyone knows of a boat with a compatible engine and outboard that's being sold for cheap, please let me know. I don't care what the rest of the boat looks like, I just need the drive components.

Thanks,

Jeremy

 

[Purduebarry]

Re: OMC Cobra Engine swap

I have the same boat with the 5.0L From what I've read and posted by others The King was for motors much bigger than 5.0's. I know of someone that repowered from a 5.0L to a 5.7L with the Cobra drive. Now then going from the 2.3 to the 5.0 may be different but others will have to provide particulars such as gear and direct swap out issues.

 

[Gary H NC]

Re: OMC Cobra Engine swap

Don or someone may correct me if i'm wrong but i believe the drive will have to be changed out also...

 

[marunr]

Re: OMC Cobra Engine swap

Yes, you'll have to replace the outdrive.

I have the same boat (I'm assuming it's a 1750), and I think you might have a problem with the extra weight of a larger engine. I believe the 4.3's were in the 1950 Bayliner Capri. Also, if you check it out, the boat itself is not worth the expense of the engine/outdrive upgrade...at least it's not something I would do.

 

[lilmandavis]

Re: OMC Cobra Engine swap

hey! i built a cobra to go behind my 460 ford. its a 30 ft boat. i like how simple they are. parts are easy to get for them. i dont have any problems. of course with maintnence anything will last as long as it isnt pushed to the limits ALL the time! plus he would have to upgrade to a volvo if he did change. or else its transom rebuild time. i bought the better gears for a few more bucks but...

 

[marunr]

Re: OMC Cobra Engine swap

hey! i built a cobra to go behind my 460 ford. its a 30 ft boat. i like how simple they are. parts are easy to get for them. i dont have any problems. of course with maintnence anything will last as long as it isnt pushed to the limits ALL the time! plus he would have to upgrade to a volvo if he did change. or else its transom rebuild time. i bought the better gears for a few more bucks but...

I wasn't thinking of just changing the gears...that would be cheaper. Should he still be concerned about the weight? How much heavier is a 4.3 than a 2.3? The boat is only rated for 750 lbs of people and/or gear with the 2.3 in it.

BTW, I don't dislike my Cobra. I've only had one major gear problem (several years ago due to a bad cable I think). Since I found this site and was given the Hastings site I've been adjusting it myself and so far, so good. And the 2.3? I bought mine new in '88 and it still purrs like a kitten when properly tuned. I can still pull up 2 slalom skiers (if they're good enough to hang on a few seconds!)

 

[Milenko]

Re: OMC Cobra Engine swap

Yes, you'll have to replace the outdrive.

I have the same boat (I'm assuming it's a 1750), and I think you might have a problem with the extra weight of a larger engine. I believe the 4.3's were in the 1950 Bayliner Capri. Also, if you check it out, the boat itself is not worth the expense of the engine/outdrive upgrade...at least it's not something I would do.

According to my repair manual, the 1750 had many different engine options. The 2.3L, a 3.0L, a 4.3L, a 5.0L, and the king cobra which is the 5.7L. According to the manual, the outdrive is the same for all engines except for the 5.7L, which is the OMC King Cobra. The book does not specify what the difference is between the Coba and King Cobra outdrives. I assumed that I'd be able to swap in the 4.3L with relative ease since the outdrives are supposed to be the same. I never even thought about the added weigh of the larger engine since my repair manual said that this boat came with larger engines from the factory. I assumed that if that was the case that the boat could handle the extra weight.

Since I got this boat for next to nothing, it would be worth it to me to spend $1000 or so to try and get a bigger engine in it - providing that I don't have to replace the outdrive. If I just have to get new manifolds and the new engine, I think I can do it for fairly cheap since I'll be doing all the work myself.

Unfortunately for me, I don't have the budget to go get a new boat. So I'm trying to make this one work until later when I might be able to spring for a newer model.

 

[marunr]

Re: OMC Cobra Engine swap

I've never seen a 1750 with anything other than a 2.3 (late 80's model that is) but I could see it holding a 3.0. I don't see any way that you could put a V8 motor in that engine compartment.

I cdon't know what kind of manual you have but the gears are definitely different on the outdrives. See this post.
http://forums.iboats.com/bbBoard.cgi?a=viewthread;fid=24;gtid=1149791

 

[speedholes]

Re: OMC Cobra Engine swap

I was going to suggest maybe a 3.0 as well. the power difference between a well worn 2.3 and a new 3.0 will feel like a 4 cyl to V8 swap in that size boat.

Wait a tic, isn't the 2.3 a Ford motor? In that case, it might not work.

Swapping to a V8 would require new manifolds, risers, another exhaust port for the outdrive for the exhaust to connect to, new motor mounts, and all of the components for the new motor (carb, etc.). As was said before, for that particular boat, I don't believe it would be worth it.

I would think it would be alalogous to throwing a 350 in an S10. It can be done, but is it really worth it?

 

[marunr]

Re: OMC Cobra Engine swap

A 3.0 would be a good upgrade I think but would require a lot of expense in the cooling and exhaust system unless you find a 3.0 OMC with all of the manifolds, risers, exhaust etc. already on it.

You can look at www.dougrussell.com for an exploded view of the cooling systems on both motors. The cost to replace it all is substantial.

 

[Milenko]

Re: OMC Cobra Engine swap

OK - I guess this isn't going to be as easy as I thought it was.

I figured that maybe I'd get lucky and an upgraded motor would be an easy swap. I guess instead of going through all that hassle, maybe I'll just rebuild the 2.3L and maybe upgrade it a bit while I have it apart. Even just the rebuild should help give it a little more "umpf."

The 2.3L does an OK job of driving the boat, as long as it's just me, the wife, and two kids. But add another adult in there and it really has a hard time getting out of the water quickly. Hopefully a rebuild will help a bit and I'll keep the money I save for a new boat!

Thanks for all the input guys.