I have an early version 1973 Merc 25ss that came with a fixed 0.061 jet in the KC16A carb. That was a good jet size when I ran it in 25ssh in the seventies in Fla. However now E10 gas is every where in Fla and I have not been able to locate non E10 fuel. What are your thoughts on jetting? Do I need to go richer because of the E10?

Should the advance be reduced because of the E10? It was raced at around 0.290" (38 degrees) BTDC.

Also the original recommendation for oil mix was 25:1, should the oil be increased because of the E10?

The engine is on a lake racer hydro in the 7000 rpm range.

Thanks