OMC Cobra 4.3?

[RVFR]

I am a fairly new owner of a 188 sea swirl spyder sport boat with a Cobra 4.3 I/O. I'm familiar with boats in general, yet they were all outboard-driven. This is my first I/O, now that said it is pretty straightforward in figuring things out, but as I move along I find there is verbiage I don't quite understand like in the mention of batwing manifolds, what's that? Then there is a thing here with this unit as it has Pertronix ignition. Which is ok I guess but read here and there it may have had a point distributor from the start. so curious what those that are in the know, know

 

[Lou C]

You don’t have bat wings so yours must be a 1991 or newer. The bat wing was a one piece manifold/elbow unit used from 1985-1990. And it probably had the OMC electronic ignition which may have been converted to a Petronix due to a lack of parts.

 

[RVFR]

Awe you are so right about the year, in a way, I should have written the year which is 1992, thank you for the what is

 

[Lou C]

You're actually lucky you have electronic ignition because the way that boat is set up the distributor is UNDER the area where the sun pad hinge is. I'd don't know how you'd access it even! The GM V6 distributor is at the rear of the engine like every other Chevy small block V8 or V6.
On my boat I can pull out the rear seats, all the supporting wood etc in about 5 min and get at just about everything. In this pic you can see the distributore behind the flame arrestor and carb.

 

[RVFR]

Wow, that is a clean unit there, you must be in part doing something as there are no exhaust manifolds. Yes, I can't count how many times I have cussed out GM for the distributor location, both on cars and trucks now this $#@! What surprised me here was yes it was electrical, yet small in diameter, the chevy Astro van we had had the 220hp 4.3 and it had TPI, be cool to see that here, if, yet the HEI unit is larger, a real bear to get to. in that, I was expecting a point system and had it planned to be ready to go find a HEI, now I read that those auto versions are not the best choice. The thing is I'd like to at least get a cap and rotor for this and so far no shop has them. While on this topic on the first outing, I find that it only pulled 4300 RPMs. I started looking into rebuilding the carb , then it was mentioned to check the timing, ah-ha. it was set at 3 degrees, so now I'm itchy to see if that improves that, as a lot of folks see 4600-4900 with basically the same weight of boat swinging a 19p prop.

 

[Lou C]

In the pic I had just installed a pair of remanufactured cyl heads since I had a bad overheat a few years before that and the head gaskets blew necessitating the repair. When I had the old heads checked there were cracks so replacement made more sense.
In boats you must use the marine version of distributors, alternators, starters and carbs. You cannot substitute auto versions due to safety concerns. If that is a 2bbl you should get 4600, if a 4 bbl you should get 4800 rpm. I have mine timed to 6*BTDC. So you likely have either a Holley 2100 or 4160. Mine being older has the Rochester Quadrajet. Properly set up it’s good power package for that size boat.

 

[RVFR]

AWE.. yea, it's a good ole Holly 2 barrel. I have had a few of their bigger cousins in a lot of the autos apart many times, so pretty comfortable digging into them, yet, it starts so good, idles somewhat ok, it's the low idle that is kind of lumpy. I can get it to 700 rpm via the tach, then it kind of fights it. We will see how this goes after a good run now that it's set at 6. My fingers are crossed that was the ticket, though I just also just read these engines prefer 90+oct fuel so... ? maybe I best top it off with better fuel too.

 

[Lou C]

I always used at least 89 in mine and the gas docks local to me sell only 93 octane.
With the dog clutch Cobra drive you want your idle to be not more than 600 in the water. In order for the drive to shift to neutral you need it to idle that low so the ESA system can lower it down to 450 rpm just momentarily so the drive will shift to neutral. If you idle is too high it won’t be able to function as designed

 

[RVFR]

Hmmm, I knew about the 600 for that shifting reason, I didn't know about the ESA doing a quick cut, kinda like the quick shifter on sport bikes then, ok While here I'm, wondering if you can recall or maybe have a photo of the timing tab. I looked up where 6 degrees should be on the zig zag, easy to see the hole for 0 each peak should be 2 degrees but taking into account how they are made and the corrosion with bent abuse I'm pretty sure I figured out where 6 degrees was. Any chance you can shed some light on that?

 

[MRS]

I do not have my OMC boat anymore I went to 4 stroke outboard. But old habits hard to break I pop on to the OMC section now and then did love the boat 4.3 also would run just under 50 mph 4600 rpm's. This what I had to do to get to the distributor plus you can see what the batwings look like. I just got to old to be crawling around I/O motors.

 

[Lou C]

 

[Lou C]

Love my Chevrolets

 

[RVFR]

where'd you find that? sheesh! I looked high and low for a diagram like that, many thanks

 

[RVFR]

Yep, that's where I have it set. Yea, me too, love my chevy..... trucks too.