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post #1 of (permalink) Old 11-25-2002, 03:57 PM Thread Starter
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4.2 Carter Choke Question

After my failed atemptes to get the 4.2 running right i have turned to the board agian. Before This problem occured i replaced the thermostat. The engine never operated above 150, but now it shoots up to 195 like a champ. I am running a nuttered carter on my 4.2. The thing just will not idle. The plug/wires are good, distibutor, good spark, good air flow, new carb base gaskets, and pretty sure the intake is not leaking. Once the engine warms up to operating temperature, it will not idle. The choke is all the way off. (plate is vertical). I have played with the idle and mixtures quite abit, but it still refuses to run right. But, if at operating temps, you happen to close the choke (plate horizontile) it will run fine. I have figured my carb is gummed up, it is time to pitch the carter, or my meetering pins have moved from when i did the nutter bypass on it?

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post #2 of (permalink) Old 11-25-2002, 05:24 PM
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Re: 4.2 Carter Choke Question

Have you removed the carb, disassembled it and cleaned out all passages? Could be dirt in the float bowl, clogged idle circuits that include those carrying fuel and those carrying air. A couple of hours and a can of aerosol carb cleaner should do the trick if you haven't already. If you are going to do it, do it right, take it right apart. Mine idled fine, but i hated the rich stink of the exhaust fumes. I find those carbs (probably like all) very sensitive to dirt or sediment in the fuel or float bowl. It will clog and unclog until thoroughly cleaned. Mine had the problem because I bought someone's project that had sat with stale fuel in it for who know's how long in his driveway.
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post #3 of (permalink) Old 11-25-2002, 06:50 PM
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Re: 4.2 Carter Choke Question

If you shut the choke plate and it runs better that would suggest that the mixture is too lean (screws too far in). If you are sure that all of the electric is fine I would start from scratch. Clamp off all of the vacuum lines except for the ported vac to the distributor advance. Get the engine up to operating temp. Shut it down and turn both of the mixture screws all the way in and then 3 turns out. Start it up. Move the screws in 1/4 turn increments each out and wait a minute or so in between each adjustment. If the computer is not making micro adjustments to the mixture it seems reasonable that it will be a little difficult to get it smooth. If the metering pins have moved to an extreme position it may be past the limit of what the adjustment mixture screws can handle.
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post #4 of (permalink) Old 11-25-2002, 08:07 PM Thread Starter
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Re: 4.2 Carter Choke Question

I am going to tear down the carb indoors. That sounds like a plan. I have also had the idle screws 5 turns out adn it would still run rough and get better as the choke plate closed.
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post #5 of (permalink) Old 11-26-2002, 12:25 AM
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Re: 4.2 Carter Choke Question

2 pieces of advice:

1) before you yank that thing, just give it a "mexican tune-up.) Put your hand over the top of the carb, and raise the rpms until it starts to choke and gag - don't let it die though. That creates a massive vacuum and hopefully whatever is in your carb will come free...

2) Have you cleaned out the idle pickup tubes in the venturi cluster? it's a pretty common fix on that carter bbd...
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