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OMC Cobra Conversion to Duo Prop

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mcdixtapa

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"My question is whether anyone

"My question is whether anyone knows if it's possible / practical to consider upgrading a 140HP FORD/OMC + OMC Cobra outdrive unit to Volvo's Duo Prop and if possible, whether I'd have to replace both engine and outdrive or if there is an adaptor kit to plug the duo prop outdrive into the existing engine.

Boat is a 1990 Spectrum Bluefin."
 
"Yes, there is a kit that prov

"Yes, there is a kit that provides both adaptation parts for the DP-S drive, and engine mounted sea water pump.
The DP-S then mates up to the OMC Gimbal Bell.

This also eliminates the ESA system and one shift cable causing the need for the main shift cable to be replaced with a longer one.

No more ESA... no more dog clutch gear engagement!

The over-all drive ratio must be correct for the 140 hp engine.

."
 
One thing remains to clear out

One thing remains to clear out:
140 HP FORD/OMC?????
Never in my book.
A 128 Ford (pinto) with the 'small' cobra. 2.3 L
A 140 GM with normal cobra. 3L
Which one??
 
Sorry Morten; The previous own

Sorry Morten; The previous owner told me it was a ford motor and that it was 140HP. I now understand that OMC's 140HP unit was a chevy 181cid.
 
"In round figures, about how m

"In round figures, about how much to upgrade to the volvo DP-S drive.

I guess there is no conversion available to the duo prop, which requires a higher torque engine."
 
"I'm not convinced that th

"I'm not convinced that the Duo Prop requires more engine torque. I do know from my own personal and professional experience, that the same engine (w/ Duo Prop) will power most hulls more efficiently than w/ a single prop drive.... hands down!
Word is, the 4 cylinder engine gain (in %) is not quite that of the gain with the V-8's.

As for price.... used or new?

Your Cobra may put some shilings in your pocket too, if sold on auction via e-Bay, for example."
 
"with shipping and taxes, even

"with shipping and taxes, even with free labour, gotta think you'd be in the $5000 to $10,000 range for new or reman stuff.

Even if you got used stuff cheap and spent 1/4 of that 10K on parts, it would rank among some of the worst bang for the buck upgrades ever in the history of boating.

I wonder if there would even be a compatible gear ratio DP for your ford engine with its WOT rpm of 5200 rpm

Maybe you could look for a trashed hull with a DP powertrain and then swapping everything to your hull might increase the value of your boat, but with the 2.3 in there, not a good idea to invest in upgrades"
 
"OK. You convinced me, Hy Stat

"OK. You convinced me, Hy Stat.

Plus, I found a web link to Volvo that indicated that it does not sell a kit for the duo prop 2.3 conversion. And the economics don't seem to justify an upgrade to even the DP-S.

Maybe best to look in the direction of a different boat with better power combination than the pinto engine coupled to a problematic first generation OMC Cobra.

Thanks, guys for all the good help."
 
"I was going to leave this one

"I was going to leave this one alone, but wouldn't be able to sleep tonight if you went away with the impression that this was a good idea in any form.

Don't spend a single dime on this setup you have.

If you just have to keep this hull find a donor boat with a bad hull and rip out the motor and drive and install everythingfrom the donor boat.

Everything meaning the motor and drive.

Some one will pay good money for the parts you rip out.

Good luck !"
 
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