oiling question for pre 64 engines

[soundchaser]

I'm wondering what exact change was made to make a 1964 40hp engine 50:1 oiling ratio when the 63 was 24:1. I have a factory 1962 manual and have been looking at the main crank and bearing setup pretty closely.

Is the difference that they drilled bigger oiling holes in the crank or something? Because it appears that all the bearings are basically the same. Did they really change something, Or did they just realize that they could run them fine with 50:1 mixture?

 

[Chris1956]

Re: oiling question for pre 64 engines

When motors went to all roller and needle bearings, they went to a 50::1 gas-oil mix. OMC completed the transition in 1964, however, some of their models had all roller/needle bearings earlier. You might PM Joe Reeves with your particular model, as he will know exactly how your motor is made, and can recommend a fuel mix.

 

[soundchaser]

Re: oiling question for pre 64 engines

Thanks for getting back, Who is Joe Reeves? I have a couple of RD22 Johnson motors I'd be interested in knowing if they could be ran 50:1.
I believe they'd be all roller bearing.

 

[JB]

Re: oiling question for pre 64 engines

You can go round in circles many times on this because both OMC and now BRP have changed their minds several times.

One thing that has not changed is that neither ever speced any pre-1964 OMC engines to use 50:1, and both always call for 50:1 in 1964 and later engines, including some models that are not all "frictionless" bearing engines. JW and JH models, for instance didn't go all "frictionless" until about 1968-70.

That means that your RD-26 should run 50:1 but the RD-22s call for 24:1.

You will find that many say that 50:1 is okay in the RD-22s. I am not one of those many, though I doubt that anyone can show you how they are any different than the RD-26 except on the model number plate.