What controls my ignition advance curve?

[vetteboy86]

I know on my older TA, it is done with weights and springs, to get your mechanical advance. I run 12 degrees initial, and another 24 which gives me a total of 36 degrees total advance.

What controls it on my corvette? Is it still done with weights and springs, or is the EST wire somehow in control. Does it have any relationship to a vacuum line on an older distributor?

Here is my problem, I checked my advance curve, and by 2000 RPMS, my car is already 45 degrees advanced. I think this is pretty much the maximum, but the car is pulling timing when I crowd it and it shifts into second. Under normal acceleration, or top gear acceleration it doens't do it as much. I did notice though that the spark retard even happens if I am sitting still and rev it up past 3000 RPMS or so. I know I need this advance to come down, but how do I do it?

 

[scorp508]

I would start by dropping your initial advance a couple degrees. Do you know how to do that properly? Your timing is controlled by many things in the ECM, and yes the EST wire is what does the actual adjustment at the distributor for you. You will see very different timings just rev'ing the engine in your driveway compared to driving down the street under load.