What's keeping my high idle cam from dropping?

[Can Can]

84 K5- 305 w/ a Q-Jet. This problem started about 3 weeks ago. No recent work was done, other than a new K&N filter installed in the factory air cleaner setup.

For some damn reason, the high idle cam won't drop down when I blip the throttle after letting the truck warm up for a couple of minutes. Just so you know, I've owned my K5 for over 14 years now, and the existing carb has been on the truck for 6 years. This has NEVER happened before. Spraying the cam mechanism down with both WD-40 and PB Blaster has done nothing. I am forced to pull off the air cleaner lid and manually click it down while I blip the throttle by hand.

The only variable is the new K&N, and I can't for the life of me think of a reason why that would affect anything........

 

[1979jimmy350]

did you maby knock a vacuum line off? have you tried cleaing the carb with carb cleaner?

 

[dyeager535]

Of course first thing make sure nothing was disconnected, like the choke wire.

Then make sure the choke is working correctly. Without it open all the way, it's not going to kick down correctly. Never ran one long enough to know if they need adjusting over time myself, but I figure it's possible. Just look at the choke plate and see if it's open all the way while it's running. If not, force it open all the way with a finger, and see if manipulating the throttle then fixes the problem.

 

[Can Can]

One of you must have some more insight in this one.........

 

[mikras1]

When mine had that problem (twice), it was a bad choke heater.

Assuming your 84 has an electric choke heater - Try to turn the key on, but don't start the enginge. If the Oil light does not go on - the choke heater is bad.

Or you can check the choke heater with an Ohm meter. Should be 5 Ohms or less. I think the parts stores call it a Choke Thermostat.

 

[diesel4me]

add weight...

I've had several Q-jets that refused to come off "fast idle" even after the choke fully opens--why I can't say,I tried the usual spraying of WD-40 an other stuff on all the linkages, and ensured the choke pull off was working and adjusted right,etc..so I got pissed and brazed a 1/4" nut on the cam,to add some more weight, so it had no choice but to drop to the lowest idle position..

Maybe not the "right" fix,but it cured my problem!..