Cold start idle issues
03-30-2017, 10:03 AM
#1
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Cold start idle issues Pretty new to carbs. I have an LM7, MS3 cam, Holley mid rise, Holley 750 with mech secondary's. Seems like during cold start it takes a good 5 plus minutes to be able to get the car idling. I'll crank it and it will pop. Add a couple squirts of fuel, crank it, it will run for like 2 seconds. Add a few squirts of fuel and it will run for 3 seconds.... eventually it will idle for long enough for me to give it a little gas and take it to about 1500-2000rpm. hold it there for a little, let go of the gas and it will sputter and die. I'll do this for a few minutes and it will eventually idle on its own no problem. Would this be a normal cold start condition with this setup?
Vid of the car idling on its own. I turned the idle down a little to see if it would still idle with low idle and it does.
https://www.youtube.com/watch?v=-UmT...ature=youtu.be
Vid of the car idling on its own. I turned the idle down a little to see if it would still idle with low idle and it does.
https://www.youtube.com/watch?v=-UmT...ature=youtu.be
03-30-2017, 03:23 PM
#2
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Maybe change ur timing ,advance it slightly and retest. Do you have a choke on the carb? Sounds ok at idle but make sure u have no minor vacuum leaks that could give u trouble specially cold
03-31-2017, 05:30 AM
#3
Does the carb have a choke? Also do you have a wideband? What are the idle AFR's when the car is warmed up?
Shouldn't be that bad if the choke is adjusted right. Even in moderate weather mine can take a couple of tries to get going. If you don't have a choke than it is going to be hard to start. All carb'd motors have a certain sequence of pedal strokes to get them started. Adds to their character.
Make 100% sure you don't have any vacuum leaks. Gaskets can shrink when cold. If no leaks and no choke, than you can try going rich on the idle screws in the cold months.
Lots of guys will claim their chokeless cars start up in hot or cold weather. I've read other posts that said the ONLY way that can happen is if they are set too rich at idle. Probably true.
Shouldn't be that bad if the choke is adjusted right. Even in moderate weather mine can take a couple of tries to get going. If you don't have a choke than it is going to be hard to start. All carb'd motors have a certain sequence of pedal strokes to get them started. Adds to their character.
Make 100% sure you don't have any vacuum leaks. Gaskets can shrink when cold. If no leaks and no choke, than you can try going rich on the idle screws in the cold months.
Lots of guys will claim their chokeless cars start up in hot or cold weather. I've read other posts that said the ONLY way that can happen is if they are set too rich at idle. Probably true.
03-31-2017, 07:25 AM
#4
If my car has been sitting for more than 24hrs, it takes a good 5 or 6 pumps of the gas peddle to give it enough fuel to start AND stay running.
It will start with only 2 pumps of the peddle, but it doesnt seem to be enough gas to keep it going when cold.
I have no choke. So once I get it started, I still have to hold it at 1500 or so for about a minute, and then maybe rev it a lil before it will idle. Sometimes it may take a minute more depending on outside temps.
It will start with only 2 pumps of the peddle, but it doesnt seem to be enough gas to keep it going when cold.
I have no choke. So once I get it started, I still have to hold it at 1500 or so for about a minute, and then maybe rev it a lil before it will idle. Sometimes it may take a minute more depending on outside temps.