Quadrajet adjustment/
 

My truck has a rebuilt quadrajet and it starts instantly when cold and fast idles at 1300rpm and can be driven away immediately even in freezing cold weather.
Hot it starts up instantly as well.But if it has been sitting for more than an hour
and its not stone cold but not hot either it can be hard to start and puffs out a lot of black smoke when it intially catches.
I was wondering if the choke is coming partly on and making it hard to start?

Re: Quadrajet adjustment/
 

When it’s hard to start do you pump the gas pedal at all?
If you do the choke can close and start rich like that.

Re: Quadrajet adjustment/
 

Yep that's most likely it.I will see if it starts on the key without pumping the throttle.It only does it in that half warm state and really only in the winter.

Here's a phone video of what happens.

https://www.youtube.com/watch?v=kEcGEwYoAS4.

Re: Quadrajet adjustment/
 

You should be able to adjust the choke to make it a bit less rich.

Re: Quadrajet adjustment/
 

It could be dripping gas into the intake while sitting making it a little rich. A lot of vehicles have issues starting when they are in between hot and cold.

Re: Quadrajet adjustment/
 

This would be my bet. If my engine is anywhere near warm and I hit the gas before starting it will get a blast of extra fuel and puff black smoke like that. It might even take some extra cranking before it fires. Took me awhile to learn how to drive it daily.

In the winter if it has been sitting for a while after being driven and the engine is still warm it will always fire up without hitting the gas. But if the choke needs to kick on it will with a tap of the gas after being started. That way it can warm up a little but will still start easily.

If any of that makes sense lol

Re: Quadrajet adjustment/
 

Cannot believe I have been driving this truck for 8 years and only just learning how to start it.As you said once it has been run and off the choke if I just turn the key and leave the throttle alone she fires straight up with no effort. thanks .

Re: Quadrajet adjustment/
 

The well plugs may be leaking gas into intake like stated previous.

I also know my carb vehicles like about 1/8-1/4 throttle when starting warm, otherwise they struggle more to start. I don't blip throttle before starting hot, I just give it slight gas to open plates and crank.

I have Q-jet, Demon, 2-jet and 4-Jet carbs between my vehicles.