Can hi-compression engine be happy on 91 octane?

[Big Fins]

It's basic 90 octane gasoline. No brand additives, as Sheet's isn't a brand, just a retailer. I use the same product, 90 octane Deathanol-free fuel in both the '69, 472 and the '76 Eldorado 500. Both have the base timing advanced 5^o BTDC over factory specs. No issues in either in performance, after shut-down run on or pinging or knocking.

I use this type of fuel because I don't use the cars as daily drivers and I don't want the $$$ carbs ruined by moonshine, which as noted in this and other threads, is called Deathanol for a reason.

You drink corn juice, not burn it in your vehicles.

[farmerbrown849]

1972 Fleetwood 75 Sedan, 472.  5th owner.  Mechanically sweet; paint and interior, not so much...I originally ran it on 89 ethanol but it would diesel on shutdown.  Switched to 93 ethanol, no dieseling.  Need to try 90 no ethanol. 

[Big Fins]

1972 Fleetwood 75 Sedan, 472.  5th owner.  Mechanically sweet; paint and interior, not so much...I originally ran it on 89 ethanol but it would diesel on shutdown.  Switched to 93 ethanol, no dieseling.  Need to try 90 no ethanol.

Idle set too high? These were 8.5:1 engines and designed to run on regular.