Mercury 850 EL - please help

[criscomp]

Hello everybody.

I have (bought a ship) a Mercury 850 EL 6cyl outboard.
The serial number is 1625859

The questions:
- what is the year when made
- which is the fuel mixture what I can use.

I'm from Hungary and I can't find any information about.

Thank You.

 

[Faztbullet]

Going to be in the 1963-64 years...original fuel mixture is 12oz of oil to 2 gallons of fuel...

 

[racerone]

Shown as a 1963 model on the list.

 

[merc850]

50:1 - 16oz to 6 gallons (470ml to 22l) is fine with a good oil.

 

[criscomp]

Thank you all of replies!

 

[criscomp]

Going to be in the 1963-64 years...original fuel mixture is 12oz of oil to 2 gallons of fuel...

It's approx. 21:1 . Is it real for todays oils?

 

[jimmbo]

The ratio was 20:1. Being that Mercury has always used anti-friction bearings in their powerheads, the 50:1 ratio using TCW-3 oils is fine

 

[criscomp]

Another question is, how often change the spark plugs ( in usage hours or travelled distances) ? I use it for long distance high speed travel and for water sports like tubing.

Todays NGK spark plugs reccomend for this Merc. model B7S spark plugs. In my engine the spark plugs are B8S. Which is the best and what happend if I change from B8S to B7S.

Thanks.

P.S.: Sometimes the power bring back to low (maybe not all cylinder works) and the boat goes nowhere. Any suggestions?