running rich
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Freshman User
Joined: Mar 2005
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running rich
I have a Stock 351M in a 66 f100. It runs rich; so much that I can't stay in a shop after 3-4 min of it running. Plugs are black, I have checked the sight hole and no fuel comes out at idle. It has a Holley 600 cfm 1850-3. I don't know what jets it has but I want to change them. I want a nice drive with good fuel economy; I don't need power very often. Which direction should I go?
Michael
Michael
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Joined: Jan 2004
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From: Eastern Pa
We will probably need a little more to go on to help. The size carb for your engine is fine. Have you checked to see that the choke is fully opened when warm? Have you tried adjusting the mixture screws? Is this a new problem that just popped up or ? What rpm is it idling at? How does it act on the road? Do you see black smoke any time? Have you tried cleaning the plugs then immediately taking it for a ride sustaining an rpm of at least 2500 for a couple of miles then shutting it down and checking a plug to see haw it looks then?
Last edited by tastyklair; Dec 19, 2005 at 01:06 PM.
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Freshman User
Joined: Mar 2005
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I think it is a blown power valve. It diesels lot, has backfired several times. Today I turned in the idle screws and it kept on running, just like the bunny. Choke is fully open when warm. Just bought the truck two months ago, has run rich the whole time. Yes black smoke when revved up. I a goning to get a kit to prevent power valve blowout and put new power valve and lower the jets. I’ll keep you informed if it worked. Might be after Christmas.
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Joined: Aug 2000
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From: PacNW
First thing I'd do is check/adjust the float levels. It's easy and it's free. It could be dumping raw gas into the intake because the floats are too high. Remember that at idle the circuit bypasses the main jets so that isn't your cause of running rich at idle.
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A couple carb tuning links.
http://www.jason.fletcher.net/tech/c...carbtuning.htm
http://www.bob2000.com/carb.htm
http://www.jason.fletcher.net/tech/c...carbtuning.htm
http://www.bob2000.com/carb.htm
