Solenoids on Carbs

[Rocker75]

I'm getting ready to have a Vintage Air air conditioning system installed on my '75 TA.
First, should I go ahead and install a Holley idle speed-up solenoid and matching bracket on my 750 cfm vac sec Holley?



This solenoid got me thinking, why couldn't I hook up a switch (the previous owner put a metal toggle switch down in the panel below the steering wheel anyway) to activate the idle speed up solenoid for when the car is cold in the morning. Sort of like the choke speeding it up to high warm up idle (my carb does not have the choke plates).

Then to go really crazy, is there a way make a two stage solenoid that could be adjusted to hold the throttle open to 65 mph? sort of like a cruise control? Has anyone done something like this? All thoughts will be carefully considered! This could be a stupid idea but since I'm "modernizing" the car, isn't this sort of what the computer does in modern cars cruise control?

[David Pozzi]

The air conditioning clutch wire would be triggering the idle solenoid when energized. You would need to isolate the clutch circuit so the toggle switch does not energize the clutch. Maybe a diode would work.

[Rocker75]

Thank you for that. I'm not very electrically or electronically oriented but that "isolation" thing makes sense. I'm anxious to hear anyone else's thoughts on this. I can't believe I'm the first one to think of it.

[TheJDMan]

An AC high idle solenoid is useful when running the AC but the choke should provide the high idle for warm up. I think using a solenoid "like a cruise control" is a spectacularly bad idea! Not only is it not dynamic when going up and down hills, using a manual switch on the dash would be extremely unsafe in case of an emergency not to mention being totally illegal. If you want cruse control, you need to install a true cruse control system.

[Rocker75]

Thank you JD

That makes sense. I don't have a choke though (for now) . Everyone tells me I don't really need it here So Cal. but something to boost up the idle a little on cold start up would be nice.

[MonzaRacer]

On cold start, I just keep working the throttle, that keeps the accelerator circuit richening the air fuel. After about 2 minutes, engine should have enough heat to idle.
As for the solenoid as cruise, pass. You could adapt an older cable ran cruise control just remember to wire in a brake cut out. Also if your trans can support a speed sensor you could use a newer unit that runs from speed sensor signal. I know couple of guys who worked through the problems,I'find out when I see them again, one guy has a TH400 with screw on speed sensor he used and it also helps run ecm for a closed loop TBI he built. Think its from a Cavalier or bigger GM car.
Works pretty good.
Another guy has a 4L60E swapped in place of 700R4, lost his speedo cable so he went electric speedo, then went GPS speedo when transplanting into different body style car.

[MonzaRacer]

Here is copy of cruise diagram from my 98 Regal
I will check but I believe you dont need to hook anything to the J or H pin to make it work I think its simply to eliminate low speed activation or inhibition.

[Skip Fix]

On my 81 TA i built for the kids I used the A/C solenoid. Well it must have been slightly stuck so I had it adjusted where it did not have full throw. One day my son was driving it and it went full throw idling about 2500. Freaked him out got is topped in a parking lot and called it "possessed" after that But then he never got used to having to deal with the choke and warm up in real cold weather either.

Holley makes a bracket, there are various Qjet brackets depending on the Q jet used. All my street cars have them.