[johnsma22]

I hate to tell you this but there no lead substitute that you can get "off the shelf" that is worth a damn. True TEL (tetra ethyl lead) for gas is illegal to use. All the so called "octane boosters" at the part stores are snake oil at best and are a fraud. Some guys here have had good luck using toluene to raise octane, you can get it at any hardware store. I'm not sure of the mixture ratio but I'm sure you could do a search here for "toluene" and get some more info. Mixing chemicals in my tank every time I fill up is not for me!

IMO you have only two realistic choices. (1) Run racing fuel either at full strength or in some ratio that you find by experimentation to eliminate the detonation. (2) Lower your compression ratio ie.. dishing pistons, changing to larger cc heads etc.

I guess you have a third choice. Do nothing and risk hammering your rod bearings into oblivion in very short order or worse, like I did.