Ethanol in a flat head engine?
E-85? Main thing I believe is the lead additive for the seals unless it has been updated.
Ethanol is primarily a problem for fuel system seals. If I were going to run ethanol in a flathead I would up the compression ratio.
You are most likely asking if E-10 or E-15 is in today's pump gas with a small amount of ethanol is compatible with your flat-head engine. The big issue will be the absence of lead in the fuel. This will be hard on the valves and seats. Either get them upgraded or run a lead substitute in your fuel.
Search Maintenance & Repair Questions
Maintenance & Repair Experts