Bravo gear ratio

[ottawamerc]

Hello, I bought a used Bravo 1 and the seller said it had a 1:5 gear ratio in it. The decal on the side has been replaced and there is no stamping there now so I marked and turned the drive input shaft one rotation and the prop shaft turned almost 3/4 rotation. What ratio do you think that would be?

Scott

 

[alldodge]

It may be a 1.65
The 1.50 should rotate 1/2 with the drive rotating 3/4 turn.

To check the 1.65 ratio, rotate the drive shaft 3 times, this should rotate the prop shaft 1.95 times, or real close to 2

 

[ottawamerc]

Ok so for 3 rotations on the drive shaft I get 2 full rotations on the prop shaft? So it looks like a 1:65! is that any good behind a 454?

 

[alldodge]

is that any good behind a 454?

Sure it will work so long as you have room to change the prop pitch. If your turning a 27 pitch then you may not have enough room. If your turning a 21 or so, then you have room to increase pitch. What prop do you have now?

 

[ottawamerc]

I'm changing the whole drive from a 350 Alpha to a 454 Bravo I have in stock now with the boat a 15.25X15 a 15.25X13 and a 16X16

 

[alldodge]

Just spit balling here, but if you were running WOT (4800 rpm) with a 15 pitch, then going to the 454, I would think along the line of a 21 to 23, which still gives room to work

 

[ottawamerc]

Wow that big of a pitch on a 27' SeaRay 268?