stupid question 115 to 85 merc

[1954bmw]

I have a stupid question, can you bolt a mid 70's inline six onto a 1973 85 horse merc, have plenty of inline six parts???? Thanks, Mark

[Capt.Insane-o]

Yup

[1954bmw]

Yup
Thank you, Capn.

[Dave S]

But l4 motors have a Different tuna so you may lose some power.

[crazy horse]

You didn't say if your going to use the 850 gearcase? The 850 has 2.3 to 1 and the six bangers are 2to1. I have a buddy that been running a 850 case on his 115 for years but he has it on a big ass deck boat so nobody cares. I've never been a fan of that combo on a big inline on a lite rig like mine.

[1954bmw]

You didn't say if your going to use the 850 gearcase? The 850 has 2.3 to 1 and the six bangers are 2to1. I have a buddy that been running a 850 case on his 115 for years but he has it on a big ass deck boat so nobody cares. I've never been a fan of that combo on a big inline on a lite rig like mine.
Is the gear case the same, just the gearing being different or is the actual gear case dimensions different??? What does this mean concerning props???

[crazy horse]

The gearcases look just alike and will work fine with your inline six. When I installed the 2.3 case on my buddies 115 he was already turning that old girl too slow so I didn't have to dig up a taller wheel for him. He was lucky that he didn't burn down his old 115 by turning so slow. His 1975 115 is still running strong and the 2.3 case is still holding up.

[Mark75H]

Everything bolts up, only the gear ratio is different. If you have the inline 6 parts transfer an inline 6 tuner to the housing. Get a tach and watch the rpm's - as noted, you will need different props. Keep the rpm below 6600 and generally above 5800.