Fuel mix for my 69 Camaro L78

[427TJ]

I ran 100LL Avgas in my 110,000-mile stock 325-horse 396 (10.25:1) and it ran great. The mix was about 50/50. Boy did the exhaust smell good. Nope, no drain bramage either.... Uhh, I mean BRAIN DAMAGE.

Problems encountered: After several tanks of pump 92 with 5 gals of 100LL mixed in each time the engine began idling fast, like 1500 rpm, and if I backed the idle adjustment all the way out it still wouldn't come down below a 1500-ish idle. Someone told me about the detergents in (or not in--can't remember) (no brain damage) 100LL causing problems. Another tidbit from a buddy was that you need "special carb gaskets" that the Avgas won't attack. Well, I decided that Avgas was becoming more trouble than it was worth and went back to straight pump 92 and reset the timing to minimize ping under load. After a tank or two the idle became 'adjustable' again and now the car idles at 800.

One of the local Unocal 76 stations sells 101 octane unleaded at the pump for $5/gal. They also sell higher octane leaded racing gas by the gallon but you gotta' pump it into a can and then transfer it to your car.

Good luck!