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Does 93 octane leave chronic soot on the transom?


Does 93 octane leave chronic soot on the transom?

Old 07-25-2013, 12:19 AM
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Default Does 93 octane leave chronic soot on the transom?

Trying to figure my carb out some and I'm thinking it maybe a shade lean on the idle side, but I have traces of soot on the transom. I run 93 octane, is that a sign of to rich or just the nature of a slower burning fuel?
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Old 07-25-2013, 12:50 AM
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Tough to tell because it might be rich at idle (causing the soot) or rich at speed. Really need an AFR gauge to take out the guess work. I won't do another motor without an AFR gauge, whether it be carb'ed or EfI. It makes life easy.
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Old 07-25-2013, 01:00 AM
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yep ! it sure does..i afr's are at 12.6 and my transom is shady grey so yes it will turn the back black..
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Old 07-25-2013, 08:17 AM
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For me and on my 502 efi........ YES it dose!!!!! 87 octane for me. Other wise I'm scrubbing the transom down after every run.
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Old 07-25-2013, 12:04 PM
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I am the soot "King" with my 496 and all of it's rich condition issues.... If your motor was designed to run 87, thats what you want to run, Higher Octane Fuels burn slower, an dreally offer no advantage (if tuned for 87). As I am to understand it. My 496 has been tuned to burn 91, yet even with 90 (and even 87) I still see soot. A lot of my soot problems were coming from Ethenol. I now only run Ethenol free 90 octane and it has cut my soot in half...
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