Rebuilt outdrive, prop question

[mattsk8]

Let me start by saying hello! I've been boating my whole life. Love watersports and absolutely love boating! I grew up on boats; my parents were big into boating so naturally I am as well. After getting married, my (our) first boat was a 17' Larson w/ a 140 merc. I sold that and picked up an 82 Mastercraft stars and stripes. I loved this boat for performance but hated it for the family. There was no room. I sold this and picked up the boat I have now, a 1993 4winns 190 horizon w/ a 5.0 cobra.

I purchased the boat fairly cheap because it had a bad outdrive; the guy ran it through some shallow water and annihilated the gears (and everything else) in the drive. I ended up paying $1800.00 to have the entire thing rebuilt after I found a gear set that was originally intended for a v6, it had one less tooth.

My basic question is this, I know this boat won't ever go like my Mastercraft did out of the hole, but it does seem like a bit of a dog. It has a top speed of 48mph on glassy water at 4700rpms. I have a 23 pitch prop on it, bigger because of the gear change. The guy I purchased the boat from said it went 52mph. Does anyone have any prop recommendations? I'd rather go better out of the hole than go good on the top as most all we do is ski, wakeboard and tube w/ it and I know it'll never be a race boat anyhow.

Someone recommended I try a stainless prop but I don't want to spend the money unless I'm positive I'll get truly noticable performance gains. Any advice?

 

[Bondo]

Re: Rebuilt outdrive, prop question

I'd rather go better out of the hole than go good on the top as most all we do is ski, wakeboard and tube w/ it and I know it'll never be a race boat anyhow.

Ayuh,... Drop down 2" of pitch, 'n try it...
Just be careful ya don't over-rev it...

 

[mattsk8]

Re: Rebuilt outdrive, prop question

Any guesstimate as to how that would effect the top end? Also, what about a vented stainless prop w/ the same pitch? Do they make that big of a difference?

 

[craze1cars]

Re: Rebuilt outdrive, prop question

You said you didn't care about top end? I doubt it'll change much if you pitch down to 21. Will probably spin 5,000 rpms on your full speed run (harmless if short durations), but it'll make a noticable improvement in holeshot. Bear in mind your motor probably is rated for 4,200 to 4,600....so by the book you're ALREADY in an over-rev with your current 23 turning 4700. Going to 21 will make the over-rev worse. But if you do watersports, that's what you need to do, and just abandon the idea of top speed runs.

What kind of 23 pitch do you have on it now? Standard run-of-the-mill aluminum? If yes, you might do well switching to a 21 of a more aggressive style, with more rake/cupping and more stern lift. Like a 4 blade Solas HR Titan 21, or a 22 pitch Stilletto 4 blade. Rpms will stay similar to where you are now, but it will probably bite better and holeshot will improve (the big key is the 4th blade). Expect to spend $350-ish for either. Solas also makes a cheaper aluminum alternative called the Amita in a 4 blade. Probably well worth trying and closer to $150, again I think I'd suggest 21 pitch in that model, but I think it will still over-rev a bit if you do a lot of high speed, and will be a step behind the stainless models all-around.

Vented prop will give very slighly better holeshot. No difference in top end.

The 1993 5.0's were known to be dogs...very underpowered for a V8, and heavy to boot. 1996 and newer got a substantial HP and torque bump with the introduction of Vortec heads and some marine models even provided a few lighter-weight aluminum components, like intake manifolds. So frankly I'm surprised your pre-vortec model is going as fast as you say it is. Overall you sound fairly well propped overall IMO, but I don't know your exact gear ratio so can't calculate slip to confirm.

Check state of tune as well...ignition timing in particular. If it's retarded even a few degrees, HP will suffer noticably. Make sure throttle butterflies are opening fully, and check compression.

Smart Tabs are another good product, reasonably priced, that improve holeshot substantially.

 

[mattsk8]

Re: Rebuilt outdrive, prop question

The 4winns has a 230hp 302 and it's running tip top. I only asked what mph I'd loose on the top cuz I'm willing to sacrifice a bit but don't want to be turning 5k at 42mph. As far as the speed, the speedo works great. Was 48 mph on very calm water according to the boat. I have since then checked the boats speedo w/ my phone's gps and it seems to be spot on. I haven't had it in water that calm since so the fastest it's gone is about 47.

I was told by the marina that rebuilt the outdrive that I wanted to stay around 4700- 4800 rpms, that was the max rpm for that engine. Just like everyone else, just trying to get the most bang for my buck. I'd hate to spend $350- $450 on a prop and be unhappy w/ it!

The prop that's on it is a cheap 3 blade, no frils aluminum prop.

Thanks for the replys btw!!

 

[mattsk8]

Re: Rebuilt outdrive, prop question

I haven't bought a prop for anything other than a merc outdrive. I assume they're different for the OMC? What do I need to look for when I'm searching for one or what info do I need to get off my outdrive?

Also, should I go w/ a 4 blade stainless 22 pitch or something different?

Thanks again for the replies!!

 

[craze1cars]

Re: Rebuilt outdrive, prop question

1993 was right at about changeover time for the Cobra. It could be of the very first cone-drive clutches with a Volvo SX style prop shaft, or I THINK most of the 1993s were the last year of the older dog-style clutch OMC drives...

Post up your outdrive's serial number in the OMC I/O section and someone will decode it for you. Or just post up a photo and someone can identify it for you. Also you can count prop shaft splines. 15 splines = old OMC style, 19 splines = new Volvo SX style. Mercruiser props NOT be a direct fit.

As for what prop and pitch you should try, my opinions are written in my reply above. I cannot offer any guarantees they will do exactly what you want, nor can anyone else. There is no substitute for test-driving locally and borrowing props from a local marina/prop shop that is willing to help you dial in the boat. Mail order something from my recommendations above at your own risk.