Avgas and advance

[Joe Bob]

I have been told that using avgas, 50/50 110 lo lead with 92 octane...using SSIs and no cat, is a waste of time unless the dizzy is set with more advance....

Anyone know a safe advance setting for the dizzy while using avgas?

[RarlyL8]

Too many variables. Ambient temperature, engine operating temperature, altitude, single/twin plug, compression ratio, etc.
Trial and error is all you can do. when it pings back it off a little.

[3liter914-6]

Originally posted by mikez:
I have been told that using avgas, 50/50 110 lo lead with 92 octane...using SSIs and no cat, is a waste of time unless the dizzy is set with more advance....

Anyone know a safe advance setting for the dizzy while using avgas?

Mike,

Unless I'm mistaken, your car ('83 SC Cabernie?), except for aforementioned exhaust mods, is basically stock. Certainly running gas of an octane rating higher than 92 is wasted with the SC ignition (ie non-adaptive) and stock ign. settings. As RarlyL8 said, it really is a crapshoot, involving guesstimations and trial and error for the varied conditions you'll encounter. For example you may be able to run more advance on a cooler day, but encounter pinging on a hot day. Something important to note is that detonation, especially in an aircooled motor (with all its extra noises) can be encountered before it is audible. I'd question wheter whatever gains (assuming there are any!) could be realized through the use of more advance and AVgas is worth the risk of hole-ing a piston or such similar nastiness.

Good luck with whatever you chose.