92 188 Spyder ?

[RVFR]

I just got a 92 sea swirl 188 spyder on what seemed to be a deal, it looks for the starters a nice fun boat. It has an OMC Cobra 4.3.. which by all accounts is 190hp. ? What I am curious about is and from what I've read here and there that the 4.3 has a somewhat lower RPM in regards to WOT, I'm reading a range from 4200 - 4800rpms depending on conditions. now granted I got this with a couple of hic-ups that I worked out, so off to the water we went. Knowing this hadn't been in the water for over 6 years had me at bay in what to expect, with a knicked-up aluminum prop of 14.5x19, 4 adults, full fuel, and sorta trimmed out on a freshwater lake I saw 4300 RPMs on the tach. No telling what the speed was, though it felt low 40s. I also felt it should do better. ?? Second trip out on saltwater after taking care of a couple more Hic-ups like fixing the Speed-O and getting a SS Michigan 14.5x 19 prop, this time 3 adults, 1/2 tank of fuel, this time I saw 4400rpms at 45 mph via speed-O on kinda light chop of 6"-8" also trimmed as best I could with a feel thing. I'm wondering if this is pretty normal? on that outing we also gave a try at fishing which means in this case we trolled leaving the engine at idle while in gear. which seemed to be ok, until, I wanted to go. LOL when I pushed the throttle forward it coughed and spit then died. Granted we were in that mode for a good 40 minutes. Yet thinking it should do this all day without much trouble, after a bit of starting and running on 2-3 cylinders by the way it ran then dies. I finally got it to do 2000rpms even at that if I thought about moving the throttle it would crap out it did this like 3 times before I left things well enough alone, but after like a 1/2 hour of this it started to run as it did, so my thoughts are I loaded up the plugs? So now I'm looking into what's the what here. Thanks for your time what a site full of boat info

 

[mr 88]

Your RPMs are in the MFGs recommended range , so I would stick with that prop. Odds are your carb is gummed up and letting to much fuel in while your trolling around. Or possibly the choke is hanging up . I can troll with a 454 all day long at 650 rpms and never have a issue with fouled plugs , same thing with my 305's. When I first got the 305s boat it would run a bit rich and actually soot up the transom. That boat had sat for a few years and the PO never ran it up to speed. New plugs , cap , wires , rotor and carbs rebuilt fixed about 95% of it , Running it at 4,000 rpms off and on over the course of a week or so and it got rid of the built up carbon and now runs 100% clean.

 

[RVFR]

Thanks for your take. good to hear being I'm somewhat new to this sort of boat thing I mean I've been around watercraft my whole life but they were 2 stroke outboards. This is a tad different being an outdrive and all , still though how hard could it be since as a hobby a fiddle with Hot Rods. But, add in god knows what I've walked into. but it all seems to be right where it just sat. One thing I didn't 'mention was the fuel, there was around 1/2 a tank meaning 15 gallons by the looks of it. on the norm, I don't mess with fuel any more than a year old, but this stuff once I started pumping it out smelled good and looked ok, I then went and had it tested since the price of fuel is going through the roof, they told me it was ok and that it had more than likely fuel stabilizer in it, so I topped it off with good ole E85 . I also scoped the intake through the carb thinking and looking for crud, it looks all good. from that I replaced the fuel pump, it was working and all the fuel filters. on another part, I did take out a couple of plugs which told me the last time it ran, it ran well so didn't bother with those. Yep cap and rotor looked good too. so off to the water we went and she pretty much fired right off the bat, from that I watched the choke do its thing. so I know that was ok, but now yes, the idle jets being they are little might play a part thank you for pointing me in some direction.

 

[roffey]

just to compare I have a 4.3 mercury alpha one gen 2. Like yours its 190 hp with a 24 inch prop (it should be a 23 inch). On the GPS I can run 51 to 54 MPH (depending on the conditions and what I had for lunch) with just me (230lb) and half a tank of gas and tach 4600 RPM. Keep in mind my boat is light and I think I have it over propped.

With the original prop, 23 inch I would tach 4800 RPM

 

[RVFR]

Wow, great info, thanks LOL, yea I had it in my mind being the original prop was the factory one to upgrade right off the bat, besides it was dinged up too. . But first, get it in the water and see how things are. I really thought and hoping I would have seen at least 4600rpms but no. I'm still working on that though, then going over prop data was telling me on a good overall user-friendly prop the 19" was the way to go. The thing was I had prior found a new SS 21" that I would love to have. then running the numbers it was still looking like the 19 was the best still though if I can get this 4.3 running really good, maybe a 21 may work, but, then I need to get over the top speed thing a bit and get the right one that works the majority of the time, Do they make a 20"? This 19" I found looks new and is a Michigan, so it's pretty good if I need to stay with it. On the matter of weight, I'm finding this boat being more a 19' ski boat weighing in, less gear and fuel to be 2300lbs, so with fuel and gear 3000 would probably be the norm. It would be interesting to go out by myself with like 1/4 tank in perfect water what can be had. I mean I have a few more Rs to go before overrunning it. Thanks for the reply, it's good to know.

 

[mr 88]

just to compare I have a 4.3 mercury alpha one gen 2. Like yours its 190 hp with a 24 inch prop (it should be a 23 inch). On the GPS I can run 51 to 54 MPH (depending on the conditions and what I had for lunch) with just me (230lb) and half a tank of gas and tach 4600 RPM. Keep in mind my boat is light and I think I have it over propped.

With the original prop, 23 inch I would tach 4800 RPM

^^^ This has nothing to do with your set up ,period. You ,we , have no idea what boat he has in comparison to yours, so the prop and everything else you can throw out the window.
In order for you to gain RPMs you have to go down in pitch. So your looking at a 17" prop or possibly 18 ,if you can find that size. A good prop shop can change the pitch to your specs or they can suggest what you need. Going up in pitch will translate to slower top end , more fuel consumption and more wear and tear on the motor. Looking down a carb with scope is useless, looking at your cap ,wires etc and then.deeming them ok is just as useless. You cannot see hairline cracks or inside the carb jets . Replace cap, wires ,rotor , plugs and have carb rebuilt . Then time it and try it.

 

[RVFR]

Yes, I can agree with all that, been there with autos. LOL boats are worse when adding in corosiron too. The top to the coil had me worried it was like Holy ****! Got it cleaned up and so far it doesn't seem to be a problem, have decent voltage there. Then taking into account how easy this starts has me going ok, it does idle well considering. This second outing was a first in what I would call a short-term idling around. it does fine in short terms like 5-10 minutes getting out of the boat slip and all, yet something is a miss there, so yes a look into the carb is in order. Next is to get my lazy ass some new plugs as well then check the timing, curious though, some say 6 degrees at idle, some say 8, being is this is pretty much a fixed advance unlike your auto there was lots of don't over advance it, yet a lot of folks swear by the 8 degrees. I'm going to have to give it a try here and there I guess, thanks for the input.

 

[briangcc]

Stingray's are typically the lightest fiberglass boats out there and are known for doing more with less HP. So I wouldn't use that as a baseline as a 23P prop seems mighty tall for a 4.3.

You should be able to find an 18P prop - work with a good prop shop to try different combos and exchange as needed.

 

[roffey]

LOL, I guess what I was trying to do was give him my info and RMP at WOT. I mentioned the prop and light boat because he likely would not be able to get the same speed but should have the same RMP.... Just trying to be helpful.

 

[mr 88]

LOL, I guess what I was trying to do was give him my info and RMP at WOT. I mentioned the prop and light boat because he likely would not be able to get the same speed but should have the same

Here we go again ! Lets not confuse the OP and stay on point . He has two issues , loading up at idle and his prop in relation to max rated RPMs. This calls for a complete tune up with new , plugs, wires, cap , rotor AND not a quick look at them with a, " there good " lets throw em back on. Next the carb needs to be rebuilt by a pro or replaced with a new one for about 350.00 . Then it's a timing light , [ split the difference and go 7* ] and a vacuum gauge to set your idle mixture screws in conjunction with a digital tach to verify your rpms while setting it up.
Roffey , I know you mean well but.... OP more than likely has a OMC outdrive as he stated his engine was badged that. I have zero knowledge about those outdrives but would be willing to bet that the gear ratio is different than your Mercruiser , which would mean you can throw your " RMP ' out the window along with what your running for pitch , sorry but your comparing apples to oranges or in this case OMC to Mercruiser.
I agree with briancc about Roffey's pitch on 4.3 Mercruiser ,unless the outdrive had a gear change or came off maybe 4 or 8 banger ( didn't do the math to figure put which would have taller gears.). Have not seen any 4.3s with that much pitch.

 

[roffey]

I'm going to stay out of this... It is what it is..

 

[RVFR]

Roffey, don't sweat it, I got what you were saying I love info and experiences and know not everyone is the same. yet there may be clues and or similarities that need to be heard, it's all the same path, just some folks look at it from another view.

 

[RVFR]

All righty, after a more in-depth looking thing over like changing plugs looking over fuel may be issues that was pointed out by a carb guy, then, Wa-la. I find it was looking to be the timing, LOL it was set at what looked to be 3 degrees. I say that because the timing prong shows clearly where Zero is. The timing gun showed it on the upper side before the first point which by what I read is 4 degrees. I have it at 6 degrees now, so we will see what it is like now.