Here is whats going on:

When i first start the car early in the morning, and immediately drop it in drive and give it gas, it has a MAJOR hesitation and even sometimes dies

But if i wait for the engine to completely warm up, it will hesitate much much less, barely at all.

To help narrow your ideas, i know its not a timing issue, because i just reset it to 8 degrees a couple days ago.

Brand new holley 570 with an electric choke. the choke is wired to + side of the coil and was getting 13.5-13.8 volts. (too much?)

I thought it could be a lean condition causing the hesitation (which is always present, just far less when engine is warm). so i readjusted the mixture screws to a complete 3 turns out.

im fresh out of ideas now

 

Its an old car, The engine needs to be warm for it to operate properly. You should let it warm up anyway.

 

+1 Fast66

you probably want to let the car warm up for a good 5+ minutes in the cold weather before putting it in drive. If you put your car in drive right after cranking it you could run the risk of screwing something up. Maybe you let it warm up but you didnt specify that.

when you crank it the engine cold it will run at a higher rpm, let it warm up and then bump the gas and it should calm down and run normal. If you dont let it warm up it will probably bounce you around and either cut off or sound like its going to cut off on you.

 

--->To help narrow your ideas, i know its not a timing issue, because i just reset it to 8 degrees a couple days ago.
1. make sure your vacuum canister is ok on distributor (suck on the hose and see if it holds the pressure. you can do that engine off)
2. make sure you have the vacuum advance hooked up to the correct port on the carburator (on the holleys it's the upper one)
3. make sure to set the engine on timing (your 8 degrees are fine) with the vacuum advance disconnected and plugged on carb side (so carb can't suck air trhough there)


-->Brand new holley 570 with an electric choke. the choke is wired to + side of the coil and was getting 13.5-13.8 volts. (too much?)
not too much. 13.5-13.8 is full voltage when car is running. that's perfect. Holley suggests to hook it up on STAT port of alternator which will have the same voltage. just the little difference of only being activated when the car is running. This means if you switch on ignition and wait for a few minutes before you start car you will have no choke operation when the car starts
Before you start the car make sure to push the throttle fully to release the ckoke.
So leave that as is

--->so i readjusted the mixture screws to a complete 3 turns out.
that has absolutely no effect when you are in choke operation.
one of the things that the choke does is pushing the throttle a bit (this is set by the fast idle screw). If the throttle is off idle the mixture screws don't come in effect anymore.

I have that carb as well (570 street avenger) and it's good for 289/302 engines right out of the box. So check for vacuum leaks around the carb, vacuum canister, hoses for power assist and the vacuum hose from manifold to automatic transmission if you have that.
If you have a pcv valve hooked up and hooked up below throttle plate (intake or lower carb) then make sure this is operating as it should or just disconnect the hose from valve cover pull the pcv and block the hose for a quick test
You can check for vacuum leaks by spraying carb cleaner or wd40 around the carburator gaskets, intake gaskets and the hoses. if idle changes while you do that you know it's pulling air from there. Don't spray into carb directly as that will falsify your results. you're best off with a spray that has a long nozzle (little hose attached) as otherwise your engine fan will blow the stuff all over the place before it gets there

that'll give you plenty to do :-)

edit: fogot to mention to check on the distributor cap and rotor and contact breaker!

Kalli

 

Mine does the same thing on cold mornings but once it warms up some then it runs fine. I don't notice it when it is warmer but if it is in the low 40's or lower temperature wise then I notice it.

Best to just let her warm up some prior to taking off on a drive.

Years ago I had an '82 F150 with a 302 in it that was the same way. Just had to start her up then go back inside to brush my teeth or get a cup of coffee or whatever till she warmed up some.

 

any engine operates best when warm (at operating temperature). Pistons are actually thinner at top when manufactured and cold and once it warms up to operating temperature they expand to make that fit perfect. I guess it';s similar with any part of the engine. So running a cold engine is not the best idea and revving a freezing engine is an absolute nightmare for it. But still I have the feeling that there's somethign wrong on his particular car. Therefore my long post.
The car should perform good when cold as well. My car doesn't hesitate or stall or anything when cold. It starts with the turn of key and I can drive it in a reasonable kind of fashion to work or anywhere else. i just don't floor it when cold.

Kalli

 

When the choke is enabled (i.e. the engine is cold), the air to fuel ratio and the engines air flow volume is going to be less than idea for performance. Think about it. When the choke is closed, you are blocking the carb intakes. You also have the issue of not achieving complete combustion when the engine block and combustion chamber is cold. In my engine, the AFR is slightly lean and the engine will stumble until the engine warms up and the choke is disabled.

 

Thanks for the responses, makes sense that the engine would stumble with the choke still activated.

One more question:

When it comes to achieving your desired park and drive idle rpms, it it best to use only the mixture screws, OR to use a combination of the idle speed screw and the mixture screws?

What i mean is, right now, it idles exactly where i want it to, and the idle speed screw is not being used (i.e. dont touching anything)

should i use a little idle screw and close off the mixture a little more or does it matter?

 

Typically you set the idle mixture screws to the AFR you want and then adjust the idle speed control to the rpm you want then recheck and readjust the mixture screws. The two often affect each other. I assume you know how to adjust the idle mixture screws to the problem level, but it you do not, it is time to get a carb tuning book.

To answer you question, you need to adjust both.