Manual choke operation question

[Streetglide2015]

My 64 C10 (283 w/ true dual exhaust) basically is running fine, but I have a choke operation question:
When engine is cold, I step on the accelerator, pull out choke almost completely, and it jumps right up. As it warms up, I slide in the choke about 1/2 way, and go. All fine.
However, even after the truck is at operating temp, good and warm, I find that if I completely push in the choke, it will run a bit rougher. If I pull it out about 1/4, it seems to be a bit smoother, yet slightly higher idle when stopped.
Is it OK to operate with the choke about a 1/4 out, all the time?

Thanks for the advice, as always!

[geezer#99]

Sure you can!
Or find the vacuum leak and fix it.

[dracko]

You’re basically enrichening the fuel/air mixture. Choking off the carb so it gets less air but the same amount of fuel. So like Geezer said, you may be compensating for a vacuum leak..

[Streetglide2015]

Thanks for the replies to this question! One other thing that may or may not effect the choke operation / air-fuel mix (you tell me):
I recently replaced the entire exhaust system from a "fake dual" set up (Y-pipe had a hole cut in, and someone welded another pipe / muffler down the other side, to make it a "dual" exhaust).
I replaced this with two separate (true dual) exhaust pipes / mufflers all the way through. I also replaced the Cherry Bombs with stock mufflers, to quiet the truck and restore the stock image.
Could this effect the 'breathing' now? Truck runs fine otherwise.

Thanks again!

[geezer#99]

Might be a little leaner but likely not enough to cause your choke requirement.
Other things to consider.
1. What’s your initial timing?
2. Have you adjusted your mix screws at all?

[Isaiah92260]

Find the factory recommended idle speed.
Set the idle with a tachometer connected under the hood

Adjust air/fuel screw with a vacuum gauge connected to the manifold.
Vacuum is good when needle on the gauge is steady, truck sounds
Like it wants to die means you tighten the screw too much or too lose, never over tighten that screw or you’re going to need a new carb or needle, you’ll do some damage.

Set the timing to factory spec.

Double check idle speed & vacuum.


If you still have the problem. Either check if the choke is adjusted properly on the carb. Then re adjust idle and vacuum.

Also you could always spray some starting fluid around the base of the carburetor or manifold in different areas(small sprays) and keep and ear out off any changes in Rpm’s.

If the rpm’s spikes where ever area you sprayed the ether at, then you’ve found your leak. Probably need to replace manifold gasket or carb base gasket, maybe a few loose screws? Or your vacuum line could be loose and need to be tighten.

Double check and inspect

I’ve always push my choke cable all the way in once my truck is warm