4.3l merc sterndrive gear ratio.

[Dave87]

Hi everyone,

I have a 4.3 merc with a sterndrive on a 1991 cadorette. I wrecked the upper gear on the stern drive that I can not count the teeth on the gear to find out the gear ratio.

Would anyone be able to help me with this.

Here is a link with a photo of the serial numbers.

Thanks

 

[Bt Doctur]

guessing 1.84

 

[Bt Doctur]

There at it again no edit feature 91-95 Alpha GEN II 1.84 # 75325A3

 

[achris]

...Would anyone be able to help me with this.....

Came out of the factory with a 1.84:1 drive ratio...



Chris.....

 

[Dave87]

Thanks for the quick reply everyone.

Ok so this leads me to my next question if I go down to a 1.62 gear ratio is that a problem?

Im trying to save some money instead of rebuilding here because rebuilding is about 1800$ cnd

 

[achris]

Thanks for the quick reply everyone.

Ok so this leads me to my next question if I go down to a 1.62 gear ratio is that a problem?...

As long as you can drop a prop size (2" less pitch) then no problem. The idea is to keep the engine WOT revs in that range 4400-4800, preferable in the 4600-4800rpm range (personally I don't find being 150rpm over will hurt anything)...

Chris.....

 

[Dave87]

Would this rob me of any power ?

 

[Bondo]

Would this rob me of any power ?

Ayuh,...... It depends on what the prop pitch was with the lower geared drive,.....

If you had a 19" pitch, a 17" pitch, should put it about where it was,.....
If you had a 15" pitch, yer gonna loose power, down low, as that's how low pitches normally go,.....

 

[Bt Doctur]

might look at SEI drives , pretty sure they ship to Ca

 

[achris]

Would this rob me of any power ?

No. As long as your engine still hit 4600rpm at WOT, all your power is still there. The lower pitch props do tend to be a little less efficient, but for the average recreational boatie, it's not noticeable.

Chris.......

 

[Dave87]

Thank you for all your help everyone!!