MarkV

I've noticed that my original '77 L-82 4 speed w/ AC, doesn't have a 'stop idle solenoid' on the carb. Can someone with an all original 4 speed '77 w/ AC let me know if their car has this? (this is what kicks the idle on the car up several RPM's when the AC compressor is engaged) I checked and my carb isn't even drilled & tapped for the bracket that holds it! I also checked the '1975-1977 Fact Book' and there is a photo of a base motor (L-48) 4 speed car w/AC (pg 143) and you can clearly see that there is no stop idle solenoid on the carb. Was this only used on auto transmission cars? It makes no sense that they wouldn't equip 4 speed cars w/ AC with this 'stop idle soleniod'. Can anyone check and let me know? This solenoid is mounted on the driver side of the carb and is in front of the carb linkage & springs. It also has a wire attached to it.

redwingvette

Sorry but I don't know the answer for sure but, an automatic trans will put a load on the motor when it is in gear and your foot on the brake where a manual trans won't. My 73 had the solenoid but it didn't have anything to do with the A/C. It was used to stop it from run-on when the engine was shut off. The solenoid was energised any time the key was turned on. Taht was what set the idle speed. when teh key was turned off the throttle plates would close all the way to stop desieling.

FeedVaal

I don't have it either. I've never noticed enough drag on the engine in neutral to need it.

Marv

If you install one on your 4 speed car the engine will "race" when the compressor kicks off and between shifts-like a sticking throttle. You won't like it. Don't ask me how I know!

MarkV

Thanks for the replies. I've pretty much found out that the 4 speed L-48 & L-82's w/ AC didn't have this solenoid. It really sucks because when you turn on the AC the car wants to shut off at idle. If you adjust the idle to run alright with the AC on, of course when the AC is off, the motor idles at 900 rpm. I wonder how GM handled this problem when these cars were new and under warranty? I would assume not very well. I wonder if there was ever a GM fix bulletin for this condition? Now that my AC is brand new, the car (barely) idles at 400 rpm with it on! :mad :mad If it isn't one thing, it's another!

page62

No. Back then, there wasn't anything much better. We simply lived with it :yesnod:

Smokehouse69

There are actually several different types of solenoids, one is the idle stop solenoid, which actually cracked the carburetor open when the car is shut down, it was used to prevent run on in automatic cars.
The second type of solenoid was used it was called the idle speed solenoid. It was used to set the idle on automatic cars with A/C. You adjusted your idle speed by screwing the plunger out or in. The plunger is up against the accelorator linkage and it kicks open when the A/C compressor is on and a extra load is placed on the engine.
I vaguely remember another type that would actually keep rpms up even when the car was in nuetral or the clutch was in. In the height of the gas shortages of the 70's I remember being pissed when trying to coast that it didn't do me much good , because that damned solenoid only slowly allowed the throttle to close.