360 idling fast untill I tap the gas

[bike5087]

This is a new little quirck my motor has - after coming to a stop, it'll idle kinda high until I tap the pedal, then it'll come back down to normal. Its a manual tranny and I just added power brakes. Any suggestions as to what to check first? I've given the throttle linkage a quick look but did'nt really see anything weird.

[knightfire83]

The first thing that comes to mind would be the fast idle cam on the carb. It comes into play when the choke is a bit closed, and kicks up the idle until the truck warms up.

After warming up the choke opens fully disengaging the cam, and idle speed drops to normal after taping on the gas pedal.

If your choke isn't working properly or is out of adjustment it can do what you are describing.

[FLATBEDFORD]

I have the same issue (70 F350 360 manual). More in cold than warm weather. I've been ignoring it. I'll keep up with this thread, maybe I cab get mine working right too.

[ares360]

you might attack your whole linkage from pedal to carb with WD-40 or a lube of your choice. I was having that problem with a dodge I was working on, and the pedal bar that goes through the firewall had a lot of friction.

It might also be that choke...look to see if its an electric or manual choke. my old carb had a manual choke that would close randomly and give me that problem.

here is a shot of my manual after I installed the cable...

[sgs]

In 1974, I was an ase certified tune up technician. That was a long time ago. I'm going from memory. This will get you close.

Assuming you have a stock type or electric choke; you could be describing a near normal condition. I say "near normal" because the choke and fast idle is supposed to stay on until the engine starts to warm. I know that you know this. There are very simple things to look at to make yours a "normal" condition. Your choke coil needs to know that the engine is warming. It knows this because of an electric lead going to the coil on some carbs or a heater hose that should be routed to a bracket that contacts the choke coil. Many people when changing heater hoses don't bother to route them back to this bracket then the choke coil doesn't pick up any heat as the engine warms. If you have an electric choke check that the choke coil is getting juice when running. If it is nether of these two ideas, Just adjust the choke coil to a leaner position. I don't remember how many notches we used to move them but it shouldn't be too many from center. If that doesn't correct the problem, look at replacing the choke coil. The choke coil itself has a bi metallic spring in it that moves your throttle from fast idle to step down and then to idle. The bi metallic springs do wear out and need to be replaced from time to time. The good news is that none of this is very hard or expensive.

sgs

[thebannister8]

on my daily driver for work ( 89 gmc )..the main throttle bar that goes into the carb housing has worn ever so slighty..unless i put a gargantuan spring on the return it does the same thing

[bike5087]

Thanks for all the suggestions - sorry it took so long for the reply, I've been out of town.

[DGrant09]

I have the same issue (70 F350 360 manual). More in cold than warm weather. I've been ignoring it. I'll keep up with this thread, maybe I cab get mine working right too.

We'll also be watching this thread.. I may be able to check the linkage tomorrow..

[willowbilly3]

It is a typical symptom on the crappy design of the auto choke on those old 2100/2150. I had new ones that didn't work right. If it's getting lazy you can sometimes adjust it a little by twisting the black thing on the side ( called a choke thermostat or chokestat) Of course you have to loosen the screws first. The chokestat opens because it has a bi-metal spring that coils.uncoils from heat variations. It is supposed to get it's heat sucked through the hot air tube that goes fron the choke housing into the exhaust manifold. Fom the other side of the manifold should be a pipe/hose back into the air horm so it can pull clean air. If that hose is gone and it pulls dirty air then it can get dirty inside the inner workings if the heated choke mechanism, or if the pipe gets rusted through then it doesn't pull enough hot air to open in a timely fashion. Uou can eliminate the whole heat tube thing by installing an electric chokestat. I think someone posted a link to one Holley sells or you can find one from a 70s Ford that will work fine. Wire the Ford one off the "S" terminal on the alternator.

[FLATBEDFORD]

Uou can eliminate the whole heat tube thing by installing an electric chokestat. I think someone posted a link to one Holley sells or you can find one from a 70s Ford that will work fine. Wire the Ford one off the "S" terminal on the alternator.

Do you know what model/year listing should I go with for the electric?

[willowbilly3]

I do not. But I would think one from a late 70s car with a 2150 2 bbl should fill the bill.