300 Carb Problems
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Freshman User
Joined: Jan 2000
Posts: 29
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300 Carb Problems
Every one I talk to has the same problem with their 1bbl carb on the 300 six....Rebuild it, it runs better for a while, but never idles right. A year later, it's rebuild again.....and still never idles right. Tear it down, nothing appears to be wrong. What's the deal with these beasts? Is there a sensible replacement option which doesn't cost several hundred? What about a progressive 2bbl?
Post Fiend
Joined: Jan 2000
Posts: 5,330
Likes: 17
From: Dryden, ON, Canada
300 Carb Problems
Sounds like you have the truck running too lean, mine had a rough idle and wouldn't idle when it was cold when I got it, richening the mixture straightened it out. I have never had to re-build one of these carbs yet, I had go re-jet mine though, running a 240 head makes the engine a little more thirsty.
Evan MacDonald
82 F100 FlareSide
42300-6 66 240 Head
83 NP435(6.69 low)
Mettalic Blue
Evan MacDonald
82 F100 FlareSide
42300-6 66 240 Head
83 NP435(6.69 low)
Mettalic Blue
Senior User
Joined: Mar 2000
Posts: 337
Likes: 0
300 Carb Problems
A 240 head makes your motor run thirsty? well i have a 300 1bbl also and mine runs rich (so rich that i can get a flame out the tail pipe when ignited with a cigarette lighter, ive adjusted/checked everything to the manual's specs. still rich, you said a 240 head makes yours run lean well, do you think a 240 head will make it run a bit leaner, also how much more umph do you get with a 240 head?
Senior User
Joined: May 2000
Posts: 137
Likes: 0
From: conneaut usa
300 Carb Problems
i have a '84 model with same problem with some research i have fond that the problem is that the needle vavle and seat is not seated properly i need to replace it evidently i replaced it must have not seated correctly so i am goin to retry it with a friend and hopefully with better results need to get better gas mileage only get 9 or 10 mpg right nowi know it is needle set becasue if i turn the mixture screw all the way in it keeps runnin mater a fact that is how i have it set right now to keep it as lean as possible till i can afford to buy a rebuild kit on the first of the month. good luck
Post Fiend
Joined: Jan 2000
Posts: 5,330
Likes: 17
From: Dryden, ON, Canada
300 Carb Problems
I'm not exactally sure of the size of the 300's chambers, but the 240's are around 62 cc, and the 300's seem to be around 84, so the cr should have went up from 8.4:1 to 10.25:1 if I figured it out right, it should give ~10 horses and ~15 lbs/ft.
I really need to get a better intake for it, It sure could use a 4bbl setup.
Evan MacDonald
82 F100 FlareSide
84 300-6, 66 240 head
83 NP435(6.69 low)
Blue
I really need to get a better intake for it, It sure could use a 4bbl setup.
Evan MacDonald
82 F100 FlareSide
84 300-6, 66 240 head
83 NP435(6.69 low)
Blue
