300 6 "missing" problem

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Nov 4, 2003 | 01:09 PM

pinguin

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Joined: Jun 2003

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300 6 "missing" problem

Hi, I have a problem with my 300 when crusing at highway speed and then lifting my foot from the gas and coasting at about 65 or so (not totally sure exactly how fast since the speedo doesn't work, but that's another problem...). I don't know what to call it, it isn't really a miss, it's a slight feeling that the truck wants to miss, sort of a muffled miss I guess. Anyway, I suspect it's something to do with carburation. I have a Holley 2300 that I adapted to the 1 barrel manifold. I basically installed it out of the box and it worked fine except for this "miss." Someone told me that it may be too rich and the excess gas is being sent into the exhaust and burns there as a small backfire like event. Other than that, it runs great, fine starting, idling, under power, great torque, just that annoying little miss. Any ideas? Maybe rejetting? Maybe unrelated to the carb? All I know is it didn't do this with the stock 1 barrel carb.

Thanks,
Mark

Nov 4, 2003 | 08:46 PM

paulfix

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Joined: May 2003

Posts: 203

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Try new pluga and then drive and warm up then try and run it for a mile or so missfiring dip clutch kill moter and pull over. Remove and inspect plugs. If rich the plugs will be dark if lean they will be really hot and light deposits. The important thing is to run for as long as possible with a steady throttle "in the missfire" to coat the plugs then kill the motor and coast to the side of the road.

A lot of goofing around but it works