Can't Reach Fast Idle screw on '83

[YellowLark]

Well, all the books tell you how to adjust the fast idle speed on my E4MC Quadrajet, even have pictures of where the adjusting screw is.

But, you simply can't get a screwdriver, or even a special flexible 18" "Carburetor adjusting tool" with little sockets, near that screw.

That's because of all the various emissions hoses in the way.

How can you adjust that screw when the engine is running? Or, do you have to remove the various hoses and keep trying to iteratively adjust by trial-and-error with the engine off ?

[Larry Schramm]

On a lot of those carbs the two mixture adjusting screw had covers put over them and the onlyway to get to them was to remove the carb and use a hack saw to break the cover off. Then reinstall the carb and make the adjustments.

[YellowLark]

Thanks, Larry,

But my issue is not with the idle mixture, it's with the fast idle speed adjustment, whose screw is (barely) visible, but not really accessible.

[NTX5467]

Just out of curiousity, why does the fast idle speed screw need adjusting?

You might have better luck adjusting the electric choke coil a few notches leaner. The thermostatic springs can tighten with age, which will make the fast idle "harder to come off", even with original factory-spec settings.

From what I've seen, there are no special tools which are specifically designed to access the fast idle speed screws on Q-Jets or Holleys. I've had some luck with a small open-end wrench of the appropriate size, or in some cases, a small ratcheting (flat ratchet with a screwdriver bit in one end) screwdriver. Neither of these "tools" are very expensive and are about all you can use without taking the carb off.

Still, though, I'm curious as to why you need to adjust the fast idle speed screw?

Curiously . . .

NTX5467

[YellowLark]

NTX,

Because that adjustment is not computer-controlled, and this car has apparently been taken apart and put back together so many times that I had to buy a parts car just to know what's missing or not hooked up.

So, that adjusting screw was totally backed out sometime in the past, and I'm looking for a way to access it while the car is running so that I can set it to the proper rpm's.

BTW, I just converted this QJet to electric choke last weekend, after seeing that the hot air choke tubes had rusted apart.

Edited April 8, 2011 by YellowLark (see edit history)

[NTX5467]

Thanks for the update and information.

Thanks,

NTX5467

[Guest pfloro]

I have successfully used a Craftsman 'ignition' open end/box wrench to make this adjustment. Rather than try to adjust it on a running cold engine when the choke is operating, I have performed it iteratively over several days with 'hood closed' cold engine starts. Unless you change the base timing, this is a 'set once & forget' adjustment.

I have always adjusted the fast idle to 'feel' and don't worry about the actual RPM. You want it high enough to keep a cold engine running but not so high that the drive line is stressed when shifting into gear.

Paul

[NTX5467]

Thanks for the further updates. I have used an "ignition" wrench too, with good results.

I concur with your strategy of fast idle speed adjustment. I generally have to fiddle with those adjustments to get things to act "right", as you mention.

Take care,

NTX5467