really high idle on cold start

[DRobb's_85]

Ok, normally when I start my truck up cold it will idle around 1100 or 1000 rpm for a minute or two and then with the tap of the throttle goes down to normal warm idle. Well today after school I cranked it up as usual and instead it revved all the way up to 1900 or 2000 rpm and would not come down until i waited a few minutes and tapped the throttle, which it then came down to the normal warm idle. For those few minutes I thought it was gonna blow up, everybody was staring at me like what are you doing hah..Anyways, its done this to me just a few times in the past, hardly ever happens. But I'd like to figure out why its doing this, I dont like it revving like that when its cold..Could it be the choke maybe? By the way, its an 85 k10 with 350 and a relatively new edelbrock 1406 carb.

[bitchin85]

first check to see if your throttle retunr springs are tight enough, then see of the throttle cableis gettin hungup anywere. if both of those are fine then its your electric choke

[vtwinsport]

I second the throttle springs, cold weather makes metal act differently including the vacuum advance.
It was 26 here last night and I noticed my vac advance was stuck closed for maybe 5 minutes this morning while the truck warmed up. I had no problems with it when I went for lunch and it was 34.
Not sure what the elec choke could be doing if it's adjusted right.

[bitchin85]

Originally Posted by vtwinsport

Not sure what the elec choke could be doing if it's adjusted right.

could be getting cold and sticking. the elec choke holds it at a litle higher idle as it warms up until the choke plate opens. could be sticking too far.. of for too long

[4wdriver]

just got a 78 k20 4x4 about a month ago it also has that carb which i knew nothing about so i went to the edelbrock web site they have the owners manual online look for that.i did notice it said some adjustment may be needed for different seasons.also that carb has a high idle mechanism which might be out of adjustment.hope that helps

[jchav62]

Did it happen to be a little colder that day? Maybe the elec choke was wound up a little tighter. The high idle screw may need to be adjusted to compensate for that...

[GMC Guy]

i'm having a similar problem with my 1406, except the electric choke takes FOREVER to open, and doesn't want to stay open. i tried adjusting the black choke mechanism but had no luck

[LiveAnimals]

My stock Qjet on my 77 does it everyday I start it up, it says right on my stock air cleaner HIGH IDLE 1500 RPM and normal idle around 6-700. The guys I talked to said its normal, I figured it does that to warm it up a little faster.

[willett]

next time it happens put your foot under the gas pedal and see if you can lift it up.

my '78 had "cruise control" until i took off the old holly with the skicky throttle linkage and put on a new edelbrock.

[DRobb's_85]

Ok well I went and did a thorough check for any sticky or stuck linkages, and everything looks fine. One thing I have noticed is that these past few days have been colder and whenever I cold start it, I have to tap the gas just a bit as soon as it turns over to keep it from revving that high. Its weird, if I just crank it up and let it go it will do just what it did and rev all the way up to 1900 and stay there till its fully warmed up. If I just tap the gas a little as soon as it turns over it stays down at the normal cold idle level (1100-1000). Should I just mess with the high idle screw? By the way what is the normal cold idle supposed to be at? thanks

[tonyscustomrides]

I have the same carb, and symptoms. all it is, since its cold the choke needs to get to a certain temp to disengage. but to get it to come off faster, just take a screwdriver, move the throttle linkage wide open, and you will see a slotted screw. back off the screw thats in the back about a turn and see what it does. also, its best when its completely cold, and when its off or else it will flood. hope this helps