I have recently added a Fast ethanol/alcohol air fuel meter on my Cole Tr 4, Blown 540.
I am running e85. The ideal number appears to be about A/F ratio of 7.5. Fast meters tell me the numbers between 6.0-9.0 is good.
The readings I got initially was A/F ratio 8.5 to 8.6 during run. That probably isn't far from where it should be, but I wanted to bring the number down (richer) slightly. I changed from 101 jet to 103 jets (QF).
That run gave me a reading of about A/F ratio of 8.3. It did make more power.
I have had limited testing time, but my questions are, would a jet change of 2 sizes or about 9% create a variation of almost a 2 and 1/2 point change in the A/F ratio and would the ideal A/F ratio of 7.5 be the same for naturally aspirated and for a roots blower set up?
(Originally posted as 6.3 and not 8.3 in error.)