Idle speed solenoid for AC

[YIIHAA]

I was lying in bed last night thinking about the usual cr*p when I came up with the idea of installing a push solenoid, with its shaft running through the idle speed screw, powered off the electrical feed to the ac compressor clutch. The idea being that I could run a low idle for cooling purposes, without having to enrichen the idle mixture to allow for the AC to start. This way I could adjust the idle without AC running and with.

I started looking in the RS catalogue for a suitable soleniod. Then googled and found that edelbrock already make such a device for exactly this purpose.
Edelbrock solenoid
Holley solenoid


Has anybody tried one of these?

[US-GTR]

That looks to be the same as a standard GM "High Idle Solenoid" that was used in the late 80's to (very) early 90's. Single wire hooke up, simple to adjust.

You don't need to have it go through the idle screw. The head of the solenoid (adjustable bolt) simply contacts a flat portion of the linkage and pushes up.

PM me if you have more questions.

[YIIHAA]

Have to see if I can get one in the UK. I can imagine the conversation at my local motor factors now

me:"I'd like a GM high idle solenoid please"
them:"what car is that off?"
me:"anything normally aspirated made by GM in the 80s"
them:"Them Vauxhalls are GM, how about a Chevette"
me:"Goodbye"


Don't suppose you have a GM part number? Google is getting me nowhere.

As luck would have it my parents are in the US this week, so I could get them to pop in to a store and bring one back. They are in Boston, Ma (Watertown), anywhere you could recommend?

[US-GTR]

I'll check into a part number for you.

The chain that I currently work for does not have a store near there. However I am sure that if they went into any auto parts store with a referable part number, they could get one.

[ultimacz]

I have used the GM "High Idle Solenoid" last year. Works generally fine but there are two problems which I found:
1. If Voltage in the electrical system drops (commonly known problem, but meanwhile solved on my car)the solenoid movement will be too weak or the head of the solenoid will not go out far enough
2. Due to the high under-hood temperatures (especially above the engine, at the carb), the solenoid survived just one season, then something melted inside I guess (just quit working)

There must be some better solution available?? Main problem on my engine is that when switching on AC, rpm drop by 300 and Vacuum to around 7. This means that my 8.5 powervalve opens at idle, which is of course is bad. Have to use 6.5 powervalve now to avoid that, but this again is not good for acceleration where the 8.5 powervalve would be much better because std. idle (w/o AC) and cruising vacuum are always above 10...

[davefiddes]

Modern engines have an Idle Air Control(IAC) that bleeds a variable amount of air into the manifold. The ECU then has the ability to bump up the idle speed to handle the extra load of the A/C. It also allows the engine to run with a higher idle when cold and to run faster if the battery voltage is getting too low. Virtually every aftermarket ECU I've seen (Holley, FAST, Edelbrock, Motec, MegaSquirt) has the ability to do this out of the box.

If you want to fix the problem ditch the carb.

[YIIHAA]

ultimacz said:

1. If Voltage in the electrical system drops (commonly known problem, but meanwhile solved on my car)the solenoid movement will be too weak or the head of the solenoid will not go out far enough ...

I intend to power the solenoid with a relay, activated by the AC clutch feed via an overide switch (like the fan overide switch, so I can set a high idle when the engine is cold)

As to the solenoid overheating, I don't have a solution to that , until my exhausts get there ceramic coat.

I don't want to ditch the carb. I like living in the stone age.

[davejw]

The 4 cylinder Lotus Esprit Turbos use this arrangement - hot engine and the one on my brother's car was 12 years old and still working...

Knowing Lotus, the parts bin cannot have been that exotic or expensive.

Dave.

[eliot]

davejw said:

Knowing Lotus, the parts bin cannot have been that exotic or expensive.

You never know, it may of come from a Vauxhall Chevette!, After all, the esprit door handle were Moris Marina

>> Edited by eliot on Friday 9th July 13:08

>> Edited by eliot on Friday 9th July 13:10

[ultimacz]

Holley supplies such a solenoid. Look at their web-site:
www.holley.com/HiOctn/ProdLine/Products/FMS/FMSCA/46-74.html

They also supply a bracket and locknut.