What is the correct gear ratio? Alpha one 1986 3.7L 4 cylinder 190

[Killerkev]

I am in the market to buy the upper unit for my alpha one outdrive. The upper unit is stamped 1.53 (Ithink it's a 3) which I believe is geared for a 8 cylinder. I was trying to find info on the web about what the proper gear ratio should be for a 1986 Mercruiser 3.7L 4 cylinder but not having much luck. Does anybody know where I can find this info? A family member has one that is a 1.98 that came off a 4 cylinder, some else tells me that I should put a 1.84? ratio on it. Any suggestions?

 

[Bondo]

Re: What is the correct gear ratio? Alpha one 1986 3.7L 4 cylinder 190

I am in the market to buy the upper unit for my alpha one outdrive. The upper unit is stamped 1.53 (Ithink it's a 3) which I believe is geared for a 8 cylinder. I was trying to find info on the web about what the proper gear ratio should be for a 1986 Mercruiser 3.7L 4 cylinder but not having much luck. Does anybody know where I can find this info? A family member has one that is a 1.98 that came off a 4 cylinder, some else tells me that I should put a 1.84? ratio on it. Any suggestions?

Ayuh,.... Yer Right,...

The 1.50:1 is for V8s,...
The 1.98:1 is for GM I4s....
Yer's is the 1.84:1....
The 1.65:1 is used for some I6s, V6s, 'n low power V8s, in Big hulls, or higher elevations...

 

[dubs283]

Re: What is the correct gear ratio? Alpha one 1986 3.7L 4 cylinder 190

you'll want the 1.84 ratio

1.98 is for the 3.0/2.5L 4 cyl engines