First off I know very little about adjusting carbs, but here is my issue. 1985 F150 with a 302. My warm idle seems to be to high (when in Park or Neutral). Cold fast idle works good, and it kicks down just fine. But with the engine warm its idling at around 2000 rpm still. Fast idle seems to be around 2400 to 2500rpm. If I put it into Drive or Reverse it drops down to 800rpm and runs perfect, but as soon as I put it back into park or neutral it shoots back up to 2000 or just under. So how do I adjust this, a picture of what to adjust would be even better haha. When its warm and kicks off fast idle I want it to be around the 800rpm. Thanks and let me know!

 

The idle speed screw would be on the shaft linkage, on the carburetor, that hooks to the linkage that comes from the gas pedal. To put it another way it would hold that shaft, that has the two round tabs that goes through the bottom of the carburetor, open. Did I totally confuse you yet?(I confused myself).

Anyway if you find that screw, turn it counterclockwise to slow the engine down.

 

Haha I should be able to find it from that description (hopefully). Just didnt want to turn the wrong screw. So I should be able to let the engine fully warm up and then turn that screw until its idling where I want it right?

 

Yes, right. A lot of times that screw will have a small coil spring around it so the screw will not turn on its own.

The latest(newest) carburetors I messed with were from 1970, but I think the 1985 carburetor should still have that screw. I have a lot of hands on with the older carburetors.

 

Okay thanks, I will let you know how it goes.

 

Okay is that the one I am supposed to adjust, the one with a spring around it? I can see how when you let off the throttle it rests up against that plunger type thing, but I tried adjusting the screw and not much changed. If I push the throttle cable back manually then it will idle around 800 rpm. But if I rev it up again it won't come back down, goes back to 1500 rpm and doesn't even rest on the plunger. So am I adjusting the wrong screw or is the spring on the throttle cable weak and not pushing back enough? Thanks!

 

First I'll say that carburetor has a lot more gizmos on it than the ones I'm used to. That is probably not the correct screw, and them newer carburetors(like yours) may not have such a screw. The idle speed may be vacuum or electric controlled.

But beings you can slow it down by pulling the throttle cable back you probably have a weak spring, as you suspect, or a sticky linkage. You might try spraying something like WD40 on the linkages. If that doesn't work you might try getting an extra spring at the hardware store and hooking it in a strategic place, just don't get one too strong or your gas pedal will push down hard and you may break something.

Good luck with it and let us know what you figure out.

 

Could I pick your brain for a second as well, this is something you might know. In this picture there is a metal rod that curves down in front of the firewall and connects to a linkage on the side of the transmission. At the top it connects to a tiny spring and linkage. It had popped off at the bottom and was just hanging freely. Any idea what this would be for? I hooked it back up now and it pulled the tiny spring and linkage a lot further back. Just curious is all.

 

That rod has a lot to do with when your transmission shifts. If you are pushing down more on the gas pedal the transmission will shift to a higher gear LATER. That rod also kicks you transmission in to what they call PASSING GEAR, say you are going 50 MPH and you floor the gas pedal to quickly and safely pass another vehicle your transmission will shift down a gear for quicker acceleration. You won't get that kick down if that rod isn't hooked up.

 

Thank you very much! Good to know and I am not sure how long it has been off for. Will have to keep an eye on it and make sure it doesn't pop off again.