Runs rough on cold start
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Elder User
Joined: Dec 2006
Posts: 913
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Runs rough on cold start
Why does my stock (except for headers and duals) '73 302 w/2bbl run rough on start up when engine is cold? Starts to smooth out after 10-15 seconds and runs good after abt. 45 seconds to a minute. But at first I have to feather the gas or it will die. Carb setting? Timing? Valves? Or is the answer: "All old trucks are like that."? Have had other older carbed vehicles act the same-guess everyone has. "Cold-blooded" is the phrase most often used. Is this fixable? Thanks.
Laughing Gas
Joined: Dec 2003
Posts: 900
Likes: 3
At the time, carburetors were the only fuel mixer offered by most car makers because fuel injection was'nt widely used yet. EFI has many sensors to let the computer know engine temp, air temp, engine speed, throttle position, altitude, etc. so it can decide how much fuel is needed for the engine to run smoothly at any given scenario. Therefore, the carb being a much simpler device, does'nt have the ability to that and can only be optimized to run well under a much narrower conditions. You could "tune" it to run well on hot days then tune it again to run well on cold days, then tune it again to run well at higher altitudes etc. You may be able to adjust your choke settings to improve things a little. My truck , car and bike all of which have carburetors take a while to warm up before they run smooth. They're kinda like me, the colder it is, the more cantakerous they are. When the temps are in the teens, my 79 has to be restarted 3 or 4 times before it runs on it's own, and my bike has to run for about 5 or 10 minutes, even on a warm day, so it won't stall when you open the throttle.
