Idle stop solenoid FYI

[Reddeye]

I recently got my AC system running after 40 years of not working on my '72 C20 and immediately encountered idle issues when the compressor was on. Found I needed an idle stop solenoid (found on Rock Auto) but was missing the bracket that bolts to my Q-jet carb.

I found several threads discussing the solenoid and even the bracket but none ever had a part number for it, only members selling NOS ones. I found that the bracket for a '71-74 Corvette will fit the Q-jet and solenoid and they sell it at CorvetteCentral.

[Mike80D]

I have one on my 72 with AC, but mine is for anti-dieseling I’ve always thought.

[body bolt]

Originally Posted by Mike80D

I have one on my 72 with AC, but mine is for anti-dieseling I’ve always thought.

It's dual purpose. It allows lower curb idle and It also serves EVAP to remove vapors from the canister. The chassis service manual has a lengthy description of operation but the schematic leaves a lot to be desired. It's funny that this item came up because yesterday mine has been stuck on. I'm thinking the temperature switch failed. I just electrically disconnected it for now.

[slikside]

Took 2 to replace mine. First one failed bench testing.

[Rich72C10]

All the research I have done on this solenoid it is for anti-dieseling for our trucks, though it doesn't mean you can repurpose it to "up" the idle for when the A/C kicks on. I'd image you'll have to tap the gas pedal at stop as it isn't all that powerful. I spent a lot of time getting a working/proper solenoid, finally got a NOS one off eBay some time back.

As I am using mine for the original purpose, I have summer and winter idle adjustments. After two summers, this has worked well for me.