63 Johnson 5.5 hp fuel mix

WillyBWright

WillyBWright

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Re: 63 Johnson 5.5 hp fuel mix

With the newer oils, you can probably lean that out to 32:1 or 4oz per gallon. Definately not 50:1.
 
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DHPMARINE

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Re: 63 Johnson 5.5 hp fuel mix

Lots of us using 50:1 on these engines.No problems.How come?<br />DHP
 
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alcan

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Dec 14, 2001
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Re: 63 Johnson 5.5 hp fuel mix

DHP,How come? That is a good question. A lot of people get away with not following directions and recomendations all the time. A lot do not as well. There are many theories as to why manufactures change the fuel-oil ratio from time to time. I do not know why you,myself and others have been so lucky in the past with this issue. I am not an engineer. The bottom line is that the manufactures recomendation is what they warranty. In this case the correct answer is 1qt. oil to six gals. gasoline or 24:1. I have disessaembled hundreds of outboards of all sizes. Of all the fifties model OMC's, It seems to me that the big twin 35hp suffers the most powerhead damage. My guess is this is probably do to the fact they were used more and pushed heavier loads. On the other hand I've had very few greesy little TD,TN 5hp models that would not run. Of course this is not a scientific study. Just an interesting observation.
 
Chinewalker

Chinewalker

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Re: 63 Johnson 5.5 hp fuel mix

I've had lots of those small OMCs apart and even ones that "ran fine" on 50:1 showed significant wear on the crankshaft mains due to a lean mix. The extra oil, plus periodical de-carboning is the way to go. If it has bronze bearings, run the rich mix (32:1 with good TCW3 rated oil and mid-grade gas). I'd even recommend it on the little 4s up into the 1970s - I've got a pile of holed blocks and broken rods from those motors - all run 50:1. I think the factory considered them disposable and 50:1 was one way to help that along. Someone gets 5-6 seasons out of a (then) $300 motor and just buys a new one. If you want to keep if for years to come, run 'er rich...<br />- Scott
 
JB

JB

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Re: 63 Johnson 5.5 hp fuel mix

Hi, Peter.<br /><br />OMC's instructions were to use 24:1 in all engines manufactured before 1964.<br /><br />Your CD-20 has sleeve bearings on the mains and on the small end of the rods. Up to the CD-19 the CDs had sleeve bearings on the big ends of the rods, too.<br /><br />It is true that many second guess the instructions of the engineers who designed the engines and get away with it. Those are tough little engines. Many others don't get away with it or shorten the life of their engines. Scott has seen it.<br /><br />How much risk are you willing to take with your engine to save a couple of bux a season on oil? That is the only payoff I know of.
 
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