gear ratios

[lockit1970]

Hello first time on a forum but at my first dead end hope someone can help .
i have a 2002 22 foot stingray with a new 4.3 , bought without a out drive I don't know what would be best ratio gear to get along with prop , ideas would be great thanks all

 

[Bt Doctur]

1.84 usually for the 4.3

 

[lockit1970]

More info , have a 1.81 on it now with Qa1912x17pitch it has a hard time making plane and wot will be at 3800 rpm max , will the gear ratio make that much difference? Along with prop I have access to what ever gear drive I need not looking for speed just make plane quickly and tubing with kids I'm not a speed demon
thanks

 

[achris]

Your almost a thousand revs short of where you should be.

I suspect there's something else not right. I put my old 4.3LX (carbed) into a 23' cabin cruiser. It had a 1.84 drive and needed a19" prop to stop it exceeding 5000rpm.

 

[lockit1970]

Then a 1,84 should work much better than the 1,81 I'm assuming as it is 22ft cubby cabin , the motor is new last year with carbs and runs strong with good compression I'm going to try it with the 1.84 thanks very much

 

[achris]

The performance difference between 1.81 and 1.84 is largely insignificant. That change came about because Merc changed the tooth count in the lower housing to reduce gear noise. Mathematically, it's less than 2%, so at 4600rpm, the difference would be about 70 rpm... I think you have other issues, not a drive ratio issue.

 

[lockit1970]

Sorry the rpm were at 4200 to 4400
typo but was hard at getting on a plan

 

[thumpar]

A Stingray is not a very heavy boat so you should be at or exceeding recommended RPM at WOT with a 17". Time to do some diagnostics. Any chance the ratio is not 1.81?

 

[Scott Danforth]

You are down on power


Make sure you are running on all 6 cylinders and your flapper have not dropped down the Y-pipe blocking exhaust flow