Throttle solenoid

Good Day. Some confusion on what exactly the throttle solenoid is for on carberator. Is it only for idle speed on A/C optioned mustangs or is it used on both A/C and non A/C cars. Can a dashpot be used in its place? Mine is missing if it ever had one. Thanks for any help.

The soloniod can be found "back in the day" on both ac and non-ac cars. They can also be found on automatic and standard trans cars. Most of the electric soloniod were use as the idle adjustments energized and when the car was turned off the throttle would drop to the 500 or600 rpm setting, closing the air off to prevent after-running.
A dashpot was found on the early to mid 60's models to slow the throttle plates down to there initial setting of the fixed screw setting. This was used to prevent stalling when you hit the gas fast and had to drop fast cause some idiot didn't move or drive off in front of you. In the later 60's dashpots became used on standard trans cars more often as the production costs were cheaper than wiring and soloniods.
Dashpots didn't prevent after-running problems, only stalling and so they were fazed out. If my memory serves me well, Most if not all 390 - 428 Mustangs used electric idle soloniods due to excessive underhood temps that added to the potential of after-running which was higher on those models.
Hope this helps, Bill - Las Vegas Nevada
Hope this info helps

Bill. Thanks so much, your response cleared up a lot of questions.

Guido- Alberta , Canada