Fuel

[x33rs]

I run the same 91 octane here in Arizona in all the cars.

The 69 Z with 11:1 compression my wife daily drives for the last 6 years and it's had nothing but 91 octane. My 70 Formula with 10.13:1 compression is the same and I drive that one nearly everyday myself.

We have a few other cars with high compression that also use nothing but 91 octane, one of them makes 724 hp on it, on motor alone.

When I built these engines I took steps to make sure the higher compression would live on the cat pee we have at the pumps by doing things like making sure the pistons are at zero deck for tight quench, degreeing the camshaft so intake valve opening is about .030-.035" more than exhaust at TDC overlap stroke, hardened seats, stainless valves, and a bunch of time, usually on a dyno, with tuning the carbs and dialing in a good ignition curve with proper vacuum advance etc....because I don't like to give up power either. Going through this isn't a cheap endeavor and may not be an option for those with survivor cars, but it's what I do to make these cars live with what's easily available while still maintaining what makes these engines so great.

I started building engines like this more than 20 years ago simply because mixing fuel had already started to become a problem and way too expensive even back then. I can't even imagine going through that now. Plus we drive our classics daily, everywhere. They have to run what ever I can find at the pumps.