Ignition timing set-up

[Johnny]

B.E. Herron wrote:

> 
> Mathew is correct.  Idle advance (mechanical only) should be 10 to 12
> degrees, no more.  Idle advance (machanical+vacuum)) should be 20 to 25
> degrees.  Total advance (mechanical) can be anywhere between 30 and 36
> degrees for max power.  Your vacuum canister should be set to give total
> advance (machanical+vacuum) in the same range for total mechanical advance
> or detonation results.

I'm not sure if I get this last statement. First of all, since manifold
pressure equals atmospheric pressure when at WOT, there is no vacuum
advance involved in total advance. What do you mean when you say "in the
same range for total mechanical advance"? Idle advance, or static
advance is just a function of where that happens to end up after you set
your total advance. Low and midrange rpm mechanical advance is just a
function of how much advance curve rate you can get away with
programming in at WOT before detonation, on the way to your total
advance at max rpm/max power. Vacuum advance setting is just a function
of how much part throttle advance you can get away with programming in
after you have set your total advance and mechanical advance curve,
without detonation.

-j-