73 merc 850 lower unit

[Dan850]

Have a 73 mercury 850 , missing lower unit. It has a short center exh housing, manual trim piston is just above lower flange, need to know what yr and hp models will fit with correct ratio. Boat is 14' 1961 gtron jetflite, 500# loaded up. Transom is 16.5", measured up into crank splines down to unit flange and is 18". Been looking on clist for a parts motor/boat to get this in the water asap....any info will help

 

[Chris1956]

Re: 73 merc 850 lower unit

Well, any 4/6 cylinder Merc from early 70s thru mid 80s will fit, if shaft length is the same. The majority of those inline merc 4/6 cylinder motors were longshaft (20"). You need to determine what you have. Your gear ratio was 2.3::1. The IL6 motors will have a gear ratio of 2::1, so a prop change will be in order.

 

[Faztbullet]

Re: 73 merc 850 lower unit

You need a short shaft 4 cylinder unit(2:3:1) off a 4 cylinder 65,80,85 as the inline 6(2:1) units kill the low end on a 4 cylinder...
Here a deal...
Mercury lower units for sale short shaft - Yakaz For sale
or try below as he has couple of hundred used units last time I was there....
Marine Parts Warehouse - Used Outboard Parts
Parts, Warehouse items in Marine Parts Warehouse store on eBay!