1977 Mercury 850 Questions

tallcanadian

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Sep 7, 2006
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I am looking for a lower unit for my 850.It's not that this one has any major issues but I noticed when I bought it that there was a bit of a grind in reverse, like it wasn't going all the way into reverse. I was thinking that the easy way is to pick up another lower unit and throw it on. My question is what lower units will fit this 850? I was told that the 3 cyl Merc in that year area will fit but looking at my '76 it doesn't look the same. Are there any other year, hp lower units that will fit?
 

Faztbullet

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Mar 2, 2008
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Re: 1977 Mercury 850 Questions

Any of the 4 cylinder engines 650/75/80/85/850 hp will work as they are 2:3:1 ratio..
 

Chris1956

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Mar 25, 2004
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27,036
Re: 1977 Mercury 850 Questions

Gearcases from IL6 motors can be used as well. The gear ratio is normally 2::1 on these, so a prop change will likely be in order.
 

racerone

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Dec 28, 2013
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Re: 1977 Mercury 850 Questions

If you shift slowly AKA ---" granny shifting " they will grind going into reverse.----Outboards MUST be shifted with a firm and quick motion.---Easing it into gear is a mistake !
 

Faztbullet

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Mar 2, 2008
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15,589
Re: 1977 Mercury 850 Questions

Gearcases from IL6 motors can be used as well. The gear ratio is normally 2::1 on these, so a prop change will likely be in order.
I disagree as it kills the bottom end grunt unless its on a small lite hull, been there and tried it.
 

tallcanadian

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Sep 7, 2006
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Re: 1977 Mercury 850 Questions

Great info from everyone. I wasn't '' granny shifting, trust me.'' It just seemed to grind a bit. Now I only ran it a few minutes when I bought and it has been sitting since. I will know more in the spring. I appreciate everyone's input.
 
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