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79 johnson fuel octane

D

dreemon

New member
"Hi, this is a 79 40 hp, with

"Hi, this is a 79 40 hp, with the older engines, were they meant to run on leaded high octane ? 50 to 1 oil? or should regular unleaded be right with 5o-1, the guy who owns it claims it runs better on the high, maybee carb clean? thanks johnny"
 
"There is no modification requ

"There is no modification required to run that engine on unleaded gasoline, and 87 octane will be fine. On some engines, the higher octane results in damage but unfortunately I have no idea which engines that might be.

When time permits, visit my store (copy/paste) at: stores.ebay.com/Evinrude-Johnson-Outboard-Parts-etc?refid=store"
 
"I have a '75 115. When l

"I have a '75 115. When leaded went out of circulaiton the dealer told me there was an OMC bulletin that recommended retarding the spark. He was emphatic about using super unleaded. I complied with the bulletin and have been using super ever since the mid-late 80's. My engine dosen't get a lot of hours, but I have never had any trouble with it.
If this detune was not necessary, I sure would like to get the 2 mph I lost. And if super isn't needed, sure would like to save 10 cents/gal."
 
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