fuel mixture

[stetsen]

I have been reading a few of the post for the 63 75 hp Johnson. I have seen several different fuel mixtures and I was told something totaly different by a mechanic. I was wondering... Which one is the best or correct one 24/1, 40/1 or 50/1?

 

[Chris1956]

Re: fuel mixture

The recommendation from Johnson (actually OMC) was 24::1 for all motors before 1964. However, some can be run successfully on a 50::1 mix. I recommend you PM Joe Reeves as he is the expert on this subject.

 

[stetsen]

Re: fuel mixture

Thank you but how do i go about asking Joe? No clue who he is and how to ask him.

 

[boobie]

Re: fuel mixture

IMHO, if I had a 1964 or prior mtr, I'd run 24:1. Oil is cheap compaired to pistons, rods and ect.

 

[JB]

Re: fuel mixture

As Chris says, stetsen, in 1964 OMC said that all 1964 and later OMC outboards are to run 50:1 and all pre-1964 outboards should stay with 24:1.

That announcement was marketing driven more than engineering driven. Actually, some models had been safe to run 50:1 for a few years before that and some were better off to stay with 24:1 for a few more years.

Most wrenches and gurus go by the types of bearings in the engine. If there are any friction (sleeve) bearings in the engine they recommend 24:1. Only if all bearings are frictionless (ball or needle) are they safe for 50:1.

Even those rules of thumb are frequently violated for years with no damage.

I don't know with certainty which category your big V4 is in, but I do know this with certainty: Oiling a 2 stroke is like watering livestock; more than is needed does no harm, less than is needed is probably fatal.

Based on that truth I recommend that you use a 24:1 mix until and unless you get a convincing argument for 50:1.

Good luck

 

[hidef]

Re: fuel mixture

The 1963 75 was a fully jeweled engine and can run 50:1 however since it is a 50 year old engine I would run 24:1.

 

[Chris1956]

Re: fuel mixture

Was that an insult directed at "people of age", or just motors?

 

[stetsen]

Re: fuel mixture

Thank you all for the help. I will indeed use the 24:1 mix. I'm sure that would have something to do with my low speed at full throttle. Would explain why i have so much oil dripping from the weep hole above my prop. Also is there a certian type of lube I should use for the lower end being as it is an electric shift? I was told standard lower end lube would be ok.

 

[stetsen]

Re: fuel mixture

Also would anyone have a manual or parts breakdown of the V4A-V4AL-15 engine? Maybe too the some tune-up reference pages. I found one, but there are some variances, like timing mark locations and follower/throttle settings for syncing. Most of it I have figured out and have the motor running good. But i would like to have her at optimum operation. Thanks again to all.

 

[F_R]

Re: fuel mixture

Thank you all for the help. I will indeed use the 24:1 mix. I'm sure that would have something to do with my low speed at full throttle. Would explain why i have so much oil dripping from the weep hole above my prop. Also is there a certian type of lube I should use for the lower end being as it is an electric shift? I was told standard lower end lube would be ok.

Electric shift motors require OMC Type C gear lube. Now renamed "Premium Blend" at Evinrude dealers. Not to be confused with other brands of "Premium". It is still known as Type C here at iboats and others.

 

[1946Zephyr]

Re: fuel mixture

Those 63 75hp motors are great motors and workhorses. Running 24:1 won't hurt it a bit. After all, that was the recemendation. A motor like that probably spends a lot of time at higher RPM's so more oil is better.

 

[JB]

Re: fuel mixture

Your questions tell me that you need, and would make good use of, a Factory Service manual, stetsen. It would be the best investment you could make. Look here: www.outboardbooks.com