Gas options

You would think a 318 would run on low octane.
But if it does ping with low octane ethanol free, try low octane with ethanol. I read somewhere that ethanol raises the octane levels higher than the posted minimum ratings.
I run my 340 with 93 unleaded with ethanol and I have 10.25 pistons. I do try to add a lead substitute but it never pings even if I don't. But I always add stabilizer to it if it is in there more than two weeks.