Cobra Outdrive gear ratios v6 vs. v8

[tmcgeachy]

I have a 1989 Cobra drive, model #985269 with a 4.3L v-6. The drive broke last year (very loud bang, then it froze up). My boat is only worth about 6000 if everything was working, so I am looking for alternatives to a rebuild.<br /><br />My question is ... I have an opportunity to buy another cobra, in good shape, but it is from a V-8.(model #985271). How different will the gearing be, and can the change be compensated by using a different propeller ? Please advise.<br /><br />Todd

 

[bluewater19]

Re: Cobra Outdrive gear ratios v6 vs. v8

I don't know the spec's but I'm sure the v-8 is geared a little taller because of the extra torque in the bigger motor. you should be able to use a smaller pitch prop and have good results provided the v-8 drive is compatable with the setup you have.

 

[tmcgeachy]

Re: Cobra Outdrive gear ratios v6 vs. v8

Thanks, that's what I was thinking as well. I believe the ratio for the 4.3 is 21/19, and the V-8 is 21/16.<br /><br />Does this mean that for 21 turns of the motor, I see 19 or 16 turns on the prop ? Or vice versa ? <br /><br />Any ideas on what the impact on rpm might be ? The boat usually ran around 4200 trimmed up, this seems a bit low for a V-6. What is my target rpm ? 21' Chris Craft

 

[Lark40]

Re: Cobra Outdrive gear ratios v6 vs. v8

Highest rpm for that engine is 4400 with the two barrel carb or 4800 with the 4 barrel.

 

[tmcgeachy]

Re: Cobra Outdrive gear ratios v6 vs. v8

Thanks for the responses.<br /><br />I just bought a package from a '87 5.7L. Leg,transom mount, exhaust mainfold,riser,etc.<br /><br />Everything from the head back. I just need the outrive (leg), what is a reasonable price for these parts. They are in excellent shape, and it seems that someone would need them.<br /><br />I had a bit of a time finding manifolds for my V-6 so I know there is some value to them.<br /><br />from a 1987 Bayliner 5.7L