Stern drive and engine mismatch ?

[Gearhead59]

I bought a 1987 Rinker V180, with the original 4.3 liter V6 engine in it. The stern drive that is on there is for a 5.0 liter, model #985687. It is a OMC Cobra outdrive. The model # of the stern drive that was originally on there but no longer anywhere to be found, was 983900,.....got that from the engine sticker. The previous owners also had a 19"prop on it. What would having the stern drive for a V8 on a V6 powered boat do for performance ? Is the gear ration in the V8 stern drive, the same as what it was for the V6 stern drive ?

 

[alldodge]

Is the gear ration in the V8 stern drive, the same as what it was for the V6 stern drive ?

In most cases no, but so long as you can find a prop which will allow the motor to reach max WOT there should not be an issue. What are you seeing or having trouble with?

 

[Gearhead59]

I'm getting around 4200 rpm out of this two barrel, 4.3 liter Chevy,....that is about 42 mph on the water according to my speedometer on my boat. I made a mistake on my earlier post,.....it's a 20" prop,.....14 1/4 X 20". Guy at the marina wants to take it out for a test drive and match up prop, etc. for me $$$. I'm not real unhappy with the performance of the boat. If you could give me an idea if that RPM range and water speed sounds about right,.....any suggestions for props would be appreciated also ! ? I also need a to get a complete seal kit for this stern drive unit, model #985687,.....I haven't been able to get anything to come up with these #s ! ? Thank you all very much !

 

[bruceb58]

Hard to believe it's a 14 1/4 x 20. Drives in that year used 15"diameter props and OMC props typically were in odd inch increments 15, 17, 19

 

[jerryjerry05]

Not all OMC props end in 15/17/19
4200 is close.
​I believe that motor was rated at 4400 at wot.
42mph ain't bad either.
You can get about any kind of prop to work if the hub fits.
What hub kit or prop is on there? Pics?
Aluminum or stainless?

Standard OMC props run anywhere from 14 1/2-20 up to a 28p
Those are the SS props.
The alum run in 15X13 to 19
Also 15x1/2 13 or 14 probably used on bigger boats or pontoons??

Pics or part numbers?
​You sure you want to reseal the whole unit??

Is it leaking?
0984458 is the part# for a complete kit.
About 50-60$

 

[bruceb58]

Yes, the aluminum props were the ones in odd increments.

 

[Gearhead59]

No Title

I have 2 props that came with the boat. Both are stainless steel. One is a 14 1/2 x 20, the other is a 14 1/4 x 20. One has no brand name on it, the other is a "Raker". Yes,....the unit leaks. Thanks for the part # for stern drive seals jerryjerry05 ! Yes,....I want to reseal the whole unit,.....or find out which seal is leaking and just change it cause the unit is tight, no wobble or looseness on either end. Anybody got any ideas on which seal might be leaking ? Here's a picture of the bellows seal, (I guess),....it is ate up,....but I don't see how that would let oil into the stern drive unit ! ?

 

[bruceb58]

Did you have water in the bellows? That would cause water to get into the drive.

Drain the drive oil and perform a pressure test. That will help you find which seal is leaking

 

[Gearhead59]

Yes,....there was a mixture of oil and water pooled in the bottom of the drive bellow, and the edge of the seal on the drive bellow looks all ate up. What do I need to pressure test the unit ? I have an air compressor. Also,....the part # given to me by jerryjerry05 was for the lower unit only, didn't include upper unit, or bellows. Plus, I'm having a real hard time finding any #'s that match what I have ,...the stern drive unit has a model # on it,....985687, serial # t0677914,....engine model #, 432apwxs serial # t0918543,...help me find a complete seal kit for upper and lower units, including bellows.

 

[Gearhead59]

I'm beginning to think if I can just replace the bellows that it will solve my water in the oil issue. Can someone give me a link to a parts supplier that would have my correct bellows part ? Or give me a part # for the drive bellow ?

 

[alldodge]

What do I need to pressure test the unit ? I have an air compressor

Keep the compressor away from the drive, should be no more then 14 psi, 10 psi is best, also for best results need a vacuum pump as well
Adults only link http://forums.iboats.com/forum/engi...drives/239516-drive-pressure-check-prior-post

 

[HT32BSX115]

engine model #, 432apwxs serial # t0918543,...help me find a complete seal kit for upper and lower units, including bellows.

Your engine is a 1986 model.

432AMWXS 1986
432APKWB 1986
432APWXS 1986
434AMKWB 1986
434AMWXS 1986
434APKWB 1986
434APWXS 1986

You can go to http://epc.brp.com/ to find part numbers or you can go to any supplier that has OMC parts for it.

I wish I had seen this thread when you originally posted. I sold a 15" x 17p stainless prop that was essentially new old stock on eBay for only $75 + shipping!

It would have probably worked just perfect for your application.

However, before you buy any props, BE SURE you have an accurate tach and use GPS to determine speed. MANY tachometers on boats are way off at the higher RPMs........... If you don't know your WOT RPM, you're wasting your time testing different props and tuning etc.....

AND before you do any testing, verify your drive ratio. (Count input shaft turns, divide by propeller turns to get ratio) ............ I.E.----> 15 engine turns divided by 10 prop turns = 1.5:1 etc......... pay attention to fractional turns also....... half, quarter turns etc.....)

Then you can easily estimate what you need to make the boat perform by using a prop-slip calculator & approx 15% slip...... http://www.go-fast.com/Prop_Slip_Calculator.htm is my favorite, there are many out there!



Regards,


Rick