distributor springs light enough ??

Light spring controls initial advance off of idle, in other words while idling light spring keeps mechanical advance from activating until rpm increases to set point where mechanical advance starts. Sometimes if one or two light springs are used to regulate mechanical advance through rpm range, this will allow governor weights to bounce off of the bottom of stop slots during rapid rpm increase. Bouncing creates several degrees of advance, and retarding in the 2600-2900 rpm range as these weights dance around for a bit until settled at higher rpm.

Using a heavy long loop spring will control this bounce, and progressively allow final three degrees of advance to occur smoothly by around 2800 rpm. The large long loop spring has no control over speed of initial mechanical advance impute, that function is solely controlled by the lighter spring.

I recurved my distributor so mechanical advance would not activate below 1500 rpm by light spring selection, and to be all in at 2800 rpm controlled by long loop spring. In park idle is 1100 rpm with this car several hundred rpm above stock mechanical advance set point. Previous owner drag raced this car, had removed the light spring, and idle timing was fluttering around up and down a few degrees in sync with cam induced lope. This made idle rpm more unsteady running up and down a hundred rpm or so, and the car a PIA to drive in traffic, or shift out of park into gear smoothly as the slightest throttle impute rapidly advanced timing which rapidly advanced several hundred rpm.

Distributor recurve spring selection available from this fellow on slantsix dot org: bigslant6fan