Thanks to all for suggestions both through this forum and PM's.
Here is an update after a Saturday of tinkering. The idle stop solenoid now works automatically as I hoped that it would.
I lengthened the replacement idle screw by about another 1/2" and widened the bracket to 2 3/8". I pushed the solenoid out to the edge of the new bracket to gain more leverage with the longer idle screw.
I rewired the solenoid using an SPST relay. The relay is triggered by the compressor wire. The solenoid is still wired with a 5 amp fused line, but it now has its own feed instead of drawing directly from the compressor line.
I run the AC idle speed at 50-100 RPM over no-load idle speed...250 was too much. This seems plenty to better cycle the freon...and I no longer see a major dip on my dash ammeter when my AC is turned on as I did without the solenoid. The change in the idle speed when the AC is turned on seems much more seamless, but is enough that my ear can tell if the solenoid is working correctly.
Once the solenoid is dialed in to run 50-100 RPM over no-load idle speed, it can be left alone. Adjusting the no-load speed with the idle screw is the only adjustment necessary for the carb. Since the new, longer idle screw remains on the same plane regardless of how the idle screw is adjusted for no-load idle, the difference between AC load and no-load remains constant.
The rig works equally well when I turn the AC on or when the compressor cycles during operation.
Revised pix are on the same photobucket link listed above.
Thanks to all my 'bolter friends for helping me to refine the original design. Hopefully anyone else attempting a similar project now has a working model to start with.
Matt
