Force lower unit on Force by Mercury top end

mkrussow

Seaman Apprentice
Joined
May 19, 2013
Messages
38
I've got a Force by Mercury top end (40 hp, serial number puts it in the 1992-1994 range) that runs well. This motor appears to utilize a Force by US Marine block with Mercury components. I've also got a gearcase from a 1989 Force by US Marine 50hp. The older gearcase will bolt up to the top end, although the castings are slightly different sizes. Someone pointed out that the older gearcase does not have thru-hub exhaust, while the top end would ordinarily utilize a gearcase with thru-hub exhaust. Will this arrangement work, or am I inviting problems? It seems like there could potentially be issues with back pressure. I'd appreciate any input someone might have.
 

jerryjerry05

Supreme Mariner
Joined
May 7, 2008
Messages
18,119
I believe the gear box was used from the 80's to 94.
It wasn't until 95 that they changed to Mercury's gear boxes.
The through hub stuff shouldn't matter.
 
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