RPM sticking sometimes.

[cbrown5385]

I’m having a slight problem I have 86 k10 with a carbureted 350. Every so often when just crushing and pulling up to and intersection the ideal wants to remain high to where I almost have to rev it a little bit to get the ideal back down to its resting spot.
I did it today coming into my drive way I got on it a little bit and the RPMs hung up until I reved it then it settled back down. Any thoughts?

 

[idahovette]

Choke linkage on the carb, throttle cable binding, look and ye shall find???

 

[PrairieDrifter]

I'd say choke not adjusted properly. You are getting up on the high idle cam because the choke isn't coming off all the way.

 

[DoubleDingo]

Possible throttle shaft. Personal experience, truck ran great, high idle when cold was perfect, idle at operating temperature was perfect. BUT! The throttle would stick sometimes. This is an original carb I rebuilt but obviously didn't check the slop in the throttle shaft. Stupid me. The throttle would stick if the pedal was applied to open the secondaries. Fortunately, yet very scary, it happened in the driveway, so when the engine took off I frantically turned off the ignition. EDIT: I verified with the engine off that it was indeed a loose throttle shaft and swapped on a different carb. I need to bush the throttle shaft on the original carb, but haven't done one before, so I am reluctant to until I can gain the courage and hope I don't ruin it.

Not saying this is happening to yours, but it could be, and it'll be obvious as the throttle shaft will be sloppy and not simply rotate.

 

[Radiohead]

Cable for throttle actuation? A wear bind developing?

 

[cbrown5385]

I’m going to have to watch the linkage and the choke I thought I had the choke adjusted well, but the stuck linkage or cable would make a lot of sense

 

[cbrown5385]

I’m also not sure if this is part of the issue but at first start up this thing SCREAMS! Then if I tap the throttle it’ll bump it down to the high idle and then if I hit it again it’ll bump down to normal idle

 

[PrairieDrifter]

I’m also not sure if this is part of the issue but at first start up this thing SCREAMS! Then if I tap the throttle it’ll bump it down to the high idle and then if I hit it again it’ll bump down to normal idle

Normal choke operation. I believe there's two steps. The high idle has an adjustment screw on the choke side of the carb.

I guarantee it's a choke adjustment issue. Not the high idle screw. But the choke is physically not disengaging, which will keep the high idle on until you tap the pedal, even after warmed up.