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I'll let my truck warm up, choke works good. My idle screw is set at around 650 rpm. I will be driving through town at operating temp and next thing you know im idling at 900-1000. I find myself messing with my idle screw alot. I just replaced the spring on it thinking that it was a little loose but that didnt seem to do much. I figured i would try having it idle at around 500 so I got out a put it at that. About 10 minutes later at a stop sign, its idling near 100-200 barely staying alive. Its really annoying because I find myself having to stare at my tachometer but I have no idea what could be causing it. Any help would be greatly appreciated.
Auto choke or manual choke? What engine? What Carb? Pic of your linkage on the carb? Pic of your choke. All of that will make this thread a bit shorter.
Agreed, I see a line coming off your ported vacuum fitting but I don't know where it's going. and even if it's connected properly your vacuum advance can could be sticking.
A bad vaccum leak, such as your booster could cause it.
Like he said it happens after warm-up. That would make me suspect of heat making the metal to expand causing binding. also you should be using studs not bolts to mount the carb.
Well I don't know if any one will still respond on here as I'm super late to respond myself, but today I took off all my vacuum lines and made sure each and every one of them was good and they were. I finally sprayed around my carb with the truck running at operating temp, and i hit a spot with carb cleaner and it would make the idle go down. I read something that if you have a vacuum leak where the carb meets the intake, if you spray it with carb clean, the idle will go up. Well my idle went down. Does that make sense? Obviously it shouldn't be sucking in air from there no matter what so I am going to get a new gasket but I really hope this solves the idle problems because it is none of the vacuum lines.
So overall, does that make sense that it makes my idle go down instead of up?
The best way is to cover the air horn slowly with a rag , if it speeds up you have a vacuum leak if it slows down you don't. this works on most leaks.
Check your timing. if your distributor or something is goofed up it will cause all kinds of idle issues. see if your advance is hooked to ported or manifold. if this all checks out I'd suspect the carb.
