1973 and 1974 mercury 850 compatibility

riley19k

Recruit
Joined
Jun 26, 2013
Messages
2
Hey everyone I'd like to start out by introducing myself my name is ray and I am new to this site and to boating as well. I just bought my first boat it is a 15.5 ft venture pacer II bass boat. when I bought the boat he gave me two mercury 850's with it he had no info on them other than the one on the boat will not run because when he bought the boat he tried to run it dry for a few minutes to make sure it ran and the belt broke when he tried to remove the pulley he gummed up the pulley by using a huge gear puller. Let me just say I don't know a whole lot about boat motors by I am mechanically inclined enough to fix these with some guidance. The motor on the boat now is a 1973 mercury 850 and the spare is a 1974 mercury 850. My real question here is are the parts off of these motors compatible and if I should work to buil one good motor out of two of them or should I see if I can just get the spare one running. He told me he's never tried so I'm sure their is a reason why. But with no info on these motors ie. last time ran or anything I'm not sure if their is anything I should check before trying to just run them. I apologize for making this so I was just hoping to cover everything.
 

Faztbullet

Supreme Mariner
Joined
Mar 2, 2008
Messages
15,570
Re: 1973 and 1974 mercury 850 compatibility

All parts will interchange except possibly blocks as you will need to see if the 73 is a 8 or 10 bolt block.(check serial #'s) Check the compression on both before you spend any $$ on them ...
 

riley19k

Recruit
Joined
Jun 26, 2013
Messages
2
Re: 1973 and 1974 mercury 850 compatibility

I appreciate the advice today my friend and I got into those two motors they both seemed to turn over well . The one on the boat now is a little rough but we pulled the spark plug and looked inside it looks very clean but also very dry it turned over very easily the spare was corroded looking inside but also turned over. We did a compression test on the spare and it was only reading at 35 which seemed a little low to me but I was turning it over with a socket and breaker bar so maybe I wasn't turning it fast enough I'm not really sure to be honest. We didn't do one on the one that's on the boat now because the flywheel and everything is off. I will also upload a few pictures after a while because I'm not sure what the parts are called that have been taken off.
 
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