Marty I have been told that some of the manufactors go below 14:1 for a length of time and then jump the mixture over 15:1 to cool the overheated valves.. The results, I've been told, is a little more mpg. So there is always a fluctuation in the pulsewidth. It seems overheating is the reason to not go below 14:1 for any length of time.
Big JIm <img src="/forums/images/graemlins/pfft.gif" alt="" />

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