Correct fuel/oil ratio for mid 1950’s Johnson

[retiredoz]

The Johnson Service Manual tenth edition – which I believe somebody uploaded for online access – has a section on Lubrication and Fuel blending starting on P81. Interesting reading in that it is very specific about the mixing process. Apparently if you just put gas in the can and add oil, it sinks to the bottom, and gets consumed first (smokey ??) while the upper layer has relatively little oil in it which may have wretched consequences.
By and large, the claim is that 24:1 is appropriate for motors prior to ’64. If you use more, they claim, you may experience more spark plug fouling and maybe excessive carbon accumulation.

[dshanks]

The 10th edition manual was one of the places I saw 24:1 which is why I was surprised when I ran across a 1963 service manual that said 16:1 for pre-1959 motors. I figured the AMOCI was the best place to get expert advise.

To combat carbon accumulation I’m planning to mix SeaFoam in the fuel. Good idea? Bad idea? Idiotic?

I just want to make sure I’m taking care of this thing so I can pass it onto my son some day. I know they’re not valuable in a monetary sense, but there’s something to be said for keeping up a motor that’s been used to take five generations of my family fishing. 🙂

[frankr]

There are a lot of people that swear by Sea Foam. Personally, I don’t think there is a problem if you use a quality TC-W3 oil that is CERTIFIED by NMMA and bears their logo. (Non) carbon deposits is one of the tests the oil must pass to get that certification.

[1946zephyr]

Well, if this infact a ’54 QD, then I would definitely go with the 16:1, especially, since you just woke it up from a long nap. I have seen a lot of posting regarding the wrist pins in the first 10 years of the QD’s These are bushing bearings only and tend to wear prematurely. So the 16:1 is just better protection. Oil is the cheapest thing you will put into a motor. 😎

[Author]

Posts