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Discussion Starter #1
Hey guys i figured I would take advantage of all the knowledge on here and actually learn something.

I have a 67 coupe with a 68 302 holley carb, Afr Heads, Air gap intake headers and probably some other stuff Im just not thinkin of now. Oh year a 2600 stall torque converter on a C4
THe car runs pretty good, its just a "cruiser" never going to the track.
So here is what i would like to learn
When I start up the car it takes two pumps of the gas and then boom she starts right up. Automatic every time, however if I dont let her warm up long enough she cuts off. Once she warms up she is good to go no issues at all.
So like I said I am looking for engine mechanics here why does a car shut off if it is not warmed up. It usually takes about 7 -10 minutes before its warm.
 

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Hey guys i figured I would take advantage of all the knowledge on here and actually learn something.

I have a 67 coupe with a 68 302 holley carb, Afr Heads, Air gap intake headers and probably some other stuff Im just not thinkin of now. Oh year a 2600 stall torque converter on a C4
THe car runs pretty good, its just a "cruiser" never going to the track.
So here is what i would like to learn
When I start up the car it takes two pumps of the gas and then boom she starts right up. Automatic every time, however if I dont let her warm up long enough she cuts off. Once she warms up she is good to go no issues at all.
So like I said I am looking for engine mechanics here why does a car shut off if it is not warmed up. It usually takes about 7 -10 minutes before its warm.
Is there a choke on the carburetor? If so, is the choke adjusted properly?

Being in L.A., you can get away without a choke. If the choke is adjusted too rich, that might explain why the engine dies.
 

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Most likely the choke is cutting off as soon as you step on the gas after starting it. This is causing it to die when it is cold. The choke should slowly step down as the car warms up. The throttle plates should not pop wide open as soon as you step on the gas.

Remove the air cleaner and watch the coke behavior as you start the car and it warms up. Before starting when you pump the gas, it should set the choke to almost closed and the high idle setting on the throttle cam. After starting if you press o; the accelerator it should open the throttle a bit more as it steps down to the next cam position. After 2-3 mins the engine should be warm and pressing the accelerator should open the choke full.
 
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Well, kind of. Sounds to me it need a little more choke. So, look at the black plastic looking cup on the passenger side of the carb. Loosen the screws enough to turn it maybe two notches "rich" and try it.
 

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Discussion Starter #5
Thanks for the quick response guys, I appreciate the problem solving aspect. My question is more of a engine dynamics questions. I know especially here in LA that you dont neccessarily have to let your car "warm up" with the fuel injected engines, so why do we have to let our carbureted engines warm up. Do engine seals need to be a certain temperature to function properly or does oil need to reach a certain temperature before being effective. I am trying to learn how my engine operates beyond the basic Suck, Bang, Push, Blow. I hope this makes sense.
 

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Here is an excerpt from 'Jalopnik'..

"The big reason is that in the cold, gasoline doesn’t evaporate as well, so the gasoline is harder to vaporize when cold, and can go into the cylinders in liquid, droplet form, where it will cling to the walls and do nobody any good.
When the engine is cold, the combustion is uneven and poor; the carb chokes off some of the air to compensate and runs richer, but less efficiently. As things heat up, everything starts to improve, and once the car is warm enough, the fuel can properly vaporize, and the car starts to idle and run smoothly. This just takes some time."


Sent from my SM-G950F using Tapatalk
 

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Discussion Starter #7
Here is an excerpt from 'Jalopnik'..

"The big reason is that in the cold, gasoline doesn’t evaporate as well, so the gasoline is harder to vaporize when cold, and can go into the cylinders in liquid, droplet form, where it will cling to the walls and do nobody any good.
When the engine is cold, the combustion is uneven and poor; the carb chokes off some of the air to compensate and runs richer, but less efficiently. As things heat up, everything starts to improve, and once the car is warm enough, the fuel can properly vaporize, and the car starts to idle and run smoothly. This just takes some time."


Sent from my SM-G950F using Tapatalk
Awesome thank you so much, I feel like i learned something today. So its the fuel vaporizing that takes time. Ok duly noted
 
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