Ignition timing set-up

[B.E. Herron]

At 04:55 PM 9/1/97 -0700, you wrote:
>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-
>

I should have said "Your vacuum canister should be set to give total
advance (machanical+vacuum)" at 3000 rpm".  You're right, at WOT, there is
no vacuum signal, but at the above rpm there is.  The statement was made
since he is using an adjustable vacuum canister and if too much advance is
dialed in, his timing at 3000 could be in the 40's before he knows it.  Not
a good situation if accel is part throttle and not full throttle.




Bradley E. Herron
'66 Mustang Fastback	'73 Camaro RS