Identify my cobra outdrive

LassePelle · Sep 4, 2009

Hi. I am trying to identify my drive by the serial number on the upper housing with no luck. Could anyone here please help me with this?

The sign says: 984542 and type t0529599. The drive says 5.0l but my engine is the 4.3l ho 205hp.

What i am looking for is the year and ratio bechause i think my prop is too big. When at wot i only get approx 4000rpm and 27 knots. The prop is 15 3/4 x 15. Any ideas wich size could fit my boat better? The boat is full planning an weight is approx 1.8 tons.

Lassep.

TowRoper · Sep 4, 2009

Re: Identify my cobra outdrive

i would have thought a 19p would be on there hmmmm????

bruceb58 · Sep 4, 2009

Re: Identify my cobra outdrive

A 15" or maybe a little smaller would be about right if that drive was originally for a 5.0. I used to swing a 17" on my 5.0 Cobra.

LassePelle · Sep 4, 2009

Re: Identify my cobra outdrive

I have been looking at Propulse props. Maybe that is what i need? This is why i would like to know about ratio and year

So i can get a prop that fits my drive.

Bondo · Sep 4, 2009

Re: Identify my cobra outdrive

The drive says 5.0l but my engine is the 4.3l ho 205hp.

Ayuh,... It's a 20+ year old barge that Doesn't have it's Original Parts,...
Everything posted here will just be a Guess...
Mine is,..
You're Over-geared will the V8 ratio...
I doubt you'll find a prop Small enough to make up the difference in Gearing....

LassePelle · Sep 4, 2009

Re: Identify my cobra outdrive

Thanks for the replies

After reading a lot of info on the web i think that the ratio for the 5.0 is 1.68:1 and the 4.3 is 1.59:1 This is not a very big difference i think, so it should be possible too get a working prop i hope

LassePelle · Sep 5, 2009

Re: Identify my cobra outdrive

Does anyone know bout the number on the drive? What year i is?

gbeltran · Sep 5, 2009

Re: Identify my cobra outdrive

According to that number it's a 1987 drive for a 5.0 with a 1.5:1 ratio. The 4.3 should have a 1.68:1 ratio. In 1989 OMC went to the 1.59 ratio for the 5.0.

LassePelle · Sep 5, 2009

Re: Identify my cobra outdrive

Thanks

When trying to calculate the size of a matching prop i get 14 1/2 x 15 approx. Does this sound ok??

gbeltran · Sep 5, 2009

Re: Identify my cobra outdrive

Do you have access to props that you can try? A 15 pitch prop isn't going to be a speed demon by any means. Was you're wide open throttle RPM with the drive trimmed up or was it still full down? Stock prop with the proper gear ratio would have probably been a 14 1/2x19 maybe a 15x17 depending on the hull, but with the gear ratio you have I don't think either of those will work if you only get 4000 now. I know there is a 3-400 rpm difference at WOT on my 4.3 depending on how the drive is trimmed. Down I get 42-4300, trimming up for speed it goes to 45-4600.

LassePelle · Sep 6, 2009

Re: Identify my cobra outdrive

The previous owner took me out for a test drive and he ran it with the drive fully down hehe. We couldn`t get more than 3600 rpm at wot. But when i tested it and tilted the drive a little up the rpm`s went up to 4000.

I also have tabs at my boat but they are only used if i am heavy loaded or the boats is not balanced.

I have tried to search many websites and the recommandation i get is a 14 1/4 x 19 or 21.

I am not looking for high performance but a good cruising speed and relatively low fuel consumption.

The average speed of theese boats with my hp is about 30 knots

Don S · Sep 6, 2009

Re: Identify my cobra outdrive

I'll move this over to the Prop forum, possibley they can help you find a usable prop, but with the wrong gear ratio it will never be right.

This_lil_fishy · Sep 6, 2009

Re: Identify my cobra outdrive

It's a possibility that's just the housing that's been replaced and the internals are out of the original housing (thus possibly the right internals) but not likely. I think you said that it's a 4.3 which should run 4200-4600 rpm. So start there, with that info you should probably prop down in size. It'll never be quick, but you might increase the life of that poor motor. Geez though, with a 15 pitch prop that's gonna be a dog slow barge.

Ian

larryhere · Mar 24, 2012

Re: Identify my cobra outdrive

LassePelle said:
Hi. I am trying to identify my drive by the serial number on the upper housing with no luck. Could anyone here please help me with this?

The sign says: 984542 and type t0529599. The drive says 5.0l but my engine is the 4.3l ho 205hp.

What i am looking for is the year and ratio bechause i think my prop is too big. When at wot i only get approx 4000rpm and 27 knots. The prop is 15 3/4 x 15. Any ideas wich size could fit my boat better? The boat is full planning an weight is approx 1.8 tons.

Lassep.

I have a 14.5x19 on my 4.3, 20 foot bowrider that works well!

Identify my cobra outdrive

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