I have a straight 6 in my f100 with a single barrel Holley carb....90 percent of the time when I get in my truck I need to pull choke out slightly and pump gas 5 times to get engine to fire up...once fired up I need to rev it to let engine warm up...... I went to another HAMBers house with same engine and truck and he just reached in the cab turned key without even getting in the truck and it FIRED RIGHT UP.... What could or would be causing this issue? Is there an adjustment I could make ? Any help would be greatly appreciated
Sounds like a restriction in the idle circuit. The idle mixture screw is what adjusts it, but you may have more of a contamination issue. 'Course, I'm no expert..... -Greg
What would I adjust to try and fix the issue. I'm just getting into working on cars and in the early learning process
There are a couple adjustment screws on a 1bbl carb. One is the idle speed, the other is the idle mixture. The speed adjustment makes the throttle open or close a little bit, you should see where it is either on the throttle arm, or as a stop for the throttle arm. Turn it one way, the idle speed drops, screw it the other way, idle speed increases. The mixture screw is threaded into the base of the carb, it has a small spring around it. Turn it in, the carb gets lean, turn it out, it gets rich. "rich" means more fuel than needed for the amount of air, lean means less fuel. I suggest you play with the mixture screw, turn it out maybe 1/4 turn and see what happens. One common trick before you start, is to screw it in all the way gently, count the number of turns it takes to seat the screw. Then unscrew it the same number of turns, and remember the number. usually between one to three turns, and you have to count half turns and quarter turns too. like 1-3/4 turns out. then you'll be able to put it back to where it was if you get lost. Usually...rich makes it run better cold, and start easier. but might make it sputter or put out black smoke when it's warm. Lean makes it run more efficiently, but can also make it cough when you open the throttle, or die, or other things. Play with it.
This might be silly, but are you sure his truck hadn't already been started that day? If my truck is cold I usually pump the pedal once or twice, and if it is cold outside I might have to pull the choke in until it warms up. But if I shut it off and turn it back on within an hour or so it starts right up no problem since there is still a little gas in the carb.
Do u mean when u get in the truck first thing in the morning, or every time you go to start the engine?? Having to the use the choke to start a car first thing in the morning is prety much what the choke is there for.
Start with the idle mixture screw about 2 1/2 turns out from seated. (Don't overtighten it- it will break easily!) Get the engine warmed up fully, and adjust the idle SPEED down as low as you can and still have the engine run smoothly. Slowly screw the MIXTURE screw in until the engine just starts to falter. Listen carefully, as you're after just the subtlest change in idle quality. When you find that point, back the screw out 1/2 a turn. I hope this makes sense. -Greg.
It very well may have but. Even if I start mine and go to my office for an hour and go back down I need to repeat same process as before...
Also check for vacuum leaks, such as loose bolts holding the carb to the manifold, loose screws holding the bottom of the carb to the main part of the carb, loose manifold bolts, cracked gaskets, cracked or missing vacuum hoses, etc.
Is the tune, points,dwell,timing,plugs all recent and right, no vacuum leaks etc.I would make sure all that is done then do what was suggested on the carb adjustment.
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