what gear ratio ?

[canman]

hi guys ,happy thanksgiving . could someone tell me what the gear ratio is on a 1986 johnson 140 , and what the gear ratio is on a 120 horse johnson ? the 140 head was replaced with a new 120 head . my mechanic tells me if they did not change the gear ratio the motor is not going to perform right . also what plugs should i run in this motor? thanks .

 

[Dhadley]

Re: what gear ratio ?

Depending on which model motor you have the gear ratio is either 2:1 or 2.25:1. The powerhead has no way to know which gear ratio it's turning. I'd be curious to know how your mechanic arrived at that conclusion.

Use Champion plugs. I'd use the QL77JC4's if it were mine. And fresh 87 octane.

 

[rickdb1boat]

Re: what gear ratio ?

The gear ratio on the 1986 140 HP is 2.00:1. Same on the 120 HP of the same year. Champion QL77JC4 would be the correct plug....