1987 305 CCC - here's the issue: I've noticed that my idling RPM of 600 will drop to 500 or so when I turn the AC on. I have to either set the curb idle to 700-ish if I plan to be cruising with AC to keep it idling reasonably at stop lights, or keep my foot on the gas to prevent it from bogging down to 500 and idling like garbage. Isn't this what the idle solenoid is supposed to do? I've read conflicting ideas on when this thing is actually meant to come on and exactly HOW it functions. In other words, it doesn't "push" the throttle up, it just allows it to rest at a higher RPM when the AC is on? Unless that's not the function of this thing at all and the behavior I'm describing is perfectly normal.

If this does sound like a solenoid problem, is there any way I can test it? Are these things adjustable for that matter? Thanks!

 

That is the function of the throttle kicker. It should also be adjusted when the A/C is on.

 

The A/C idle solenoid works as you described. By applying 12v to the terminal it activates the rod, extending it outward to push against the throttle arm and increase idle speed when the A/C is running. The solenoid does not generally have enough strength to move the throttle arm by itself and relies on extension occurring when the throttle arm is not resting in the idle position. This can also be accomplished by touching the gas pedal slightly to raise the throttle above the idle position, allowing the A/C solenoid rod to extend. Once extended it can hold in the extended position indefinitely (as long as there is 12v) to keep the idle high for A/C conditions. You are correct in stating it does not "push" the throttle up, but allows it to "rest" at a higher throttle position. It should be adjustable, and you can test it by applying 12v power to the terminal. The rod should immediately extend and stay locked in the extended position with 12v applied. You will have to take the throttle pressure off the rod for it to extend.

I have an Edelbrock 1406 on mine and didn't feel like paying high Edelbrock prices for their branded A/C solenoid so I ordered a NOS quadrajet solenoid on Ebay for $15 and made a simple bracket to accomplish the same thing. I wired it to the A/C circuit to activate and keep idle a couple hundred RPM higher any time the A/C system is on.

 

The CCC cars have a more complex control system for it than just the AC.

It energizes whenever the RPMs are above about 1400 or so; then as the RPM decreases from there, eventually it lets go. It's particularly important in the stock-shift cars; as you shift, in between gears, as you pop your foot off the gas and the throttle slams closed, you get a YUUUUUUUUUUUUJJJJJJJJE belch of emissions (unburned fuel and carbon monoxide) since the carb keeps feeding fuel for a brief instant before the fuel flow slows down in response to the decreased air flow. This function of the solenoid partially alleviates that, by keeping SOME airflow going for that short interval of time.

The solenoid itself is adjustable. You can screw the plunger in and out to tune its operation. Curb idle should be set to 650 - 700 or so, as you prefer; then the point the solenoid holds the RPMs up to can be set with the plunger. Yours is probably that odd shape like a flower or something, I know of no tool for it although logic says there must have been one at some time; I just use channellocks, VERY CAREFULLY so as not to leave pe**** tracks on it. If you back it out too far it will NEVER let the idle return to normal, which is a major pain. It's hard to get it just right, and you'll probably find that if it works the throttle thing right, it'll be a little too aggressive on the AC (like, it'll hold the idle at 1000 or something).As said it doesn't have enough nads to kick the throttle out by itself, it can only hold it out after the throttle has already been opened. At its best it'll probably hold the idle up at 1100 or so with the AC off and fully extended; I'd suggest setting it to that as a starting point, and tune from there to see what you can get.

 

Thanks for all the feedback everyone. Im trying to adjust this thing but I'm worried Im doing something wrong. Ive attached two pictures, one of the solenoid disengaged and all the way. The other engaged with the AC on. There is no contact at either point with the throttle linkage. Do I understand that to adjust this, I engage the AC and then twist the actual rod with vice grips? I feel like ill bust the thing doing that, but if that's whats up, thats what ill do. Thanks!

 

Doesn't look like the right solenoid; looks like off of a 70s car. But, no worries. If it does what it needs to do, it's all the same.

Since yours has the hex head, you don't have to use vise-grips or whatever. You get to use an open-end wrench. 11 or 12mm if memory serves.

 

Unfortunately,it's NOT doing what it needs to do because I can't get it to extend far enough to make contact with the throttle at all. I can get it to screw IN, but that's as far extended out as it'll go. Do I need to hunt around for a new solenoid? This is what that car has had on it for two years but it's never done what it's supposed to, so maybe it is the wrong one?

 

An alternative might be to drill an additional hole in the mounting bracket. It appears that there is sufficient space to drill a new lower hole, and the increased angle will not place the solenoid onto the intake. The increased angle should also not adversely affect the operation of the solenoid against the bellcrank.

 

That might work. But I think I'd reserve modifying that one as a last resort. There were LOTS of those made, they were on trucks, full-size cars, etc.; shouldn't be THAT hard to come up with the right one.

Seems to me the one for these carbs is held onto the bracket by a big nut kinda like what electrical conduit uses, and doesn't have that plastic cover over the end. But I could easily be wrong as always.

 

Is there any way I can tell for sure that this is the incorrect idle stop solenoid before I throw 60 dollars for a new one? If the part is correct then is it possible the problem isn't the solenoid but the throttle linkage?

EDIT: I've just had another thought - could the idle stop solenoid's lack of contact have anything to do with my car dieseling in the winter, when the engine is very cold and I'm shutting it down before the engine has warmed up? Just an idea.

 

It might, but probably not.

I think actually that's what the solenoid you have there was originally for... in the mid 70s they had SO MUCH trouble with run-on like that, that they actually equipped carbs with a solenoid that was energized 100% of the time the ignition was on. I have a 74 454 like that. You used the normal curb idle screw to set the idle to like 450 or some such with the solenoid unplugged, then set the ACTUAL idle with the solenoid, to 700 or whatever. Of course the linkage piece it bumped up against could easily have been different, which is why if it's one of those, it doesn't quite fit right. Your linkage looks right because it has the proper provision for a 700 TV cable which obviously a mid-70s car would not. More likely it's the solenoid that's mismatched.

I'd check boneyards before I'd try to buy a new one. Especially if the bracket you have isn't right either. Which it very well might not be.

 

Hey everyone, just an updated in case anyone is having a similar issue in the future. And also, I feel stupid. It's absolutely the correct solenoid, but adjusting it was just HORRENDOUS. It didn't want to twist so I assumed that was as far as it extended. Put her in a vice and applied some real muscle, and finally broke it loose enough to get it extended out. Works like a charm now. Thanks everyone!

 

The Neanderthal's thought process: (speaking strictly for myself)

If at first it doesn't work, use more force. If it breaks, NBD... you needed a new one anyway.