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Old 04-07-2004, 05:47 PM
dion's Avatar
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flat spot during acceleration

this just started in the last couple weeks. when getting on the highway or just flooring it accelerates quick and moves up steadily but after a few seconds I notice a very quick "flat spot" where the acceleration decreases and then continues upward again.

I've checked the filter inside the carb (Q Jet) and the inline and both are fine and no vacuum leaks that I can find. plugs, wires and timing are good.

I did recently re-jet the primaries from 71 to 73 jets but how could that have anything to do with it? or could it?

the fuel pump is 2 years old.

the engine is a built 350 with 4800 miles on it, if anybody wants the specs let me know and I'll post them.

thanks guys.

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Old 04-07-2004, 05:49 PM
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Go back to the 71's and see if it disappears.
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Old 04-07-2004, 07:43 PM
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that's the plan Friday, thanks Chuck
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Old 04-08-2004, 01:14 PM
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Don't Q-jets have metering rods? Did you change those out to match the jets? I have messed with metering rod carbs in the past(not Q-jets) but have had good success when just going up a couple jet sizes without changing out the rods too.

Sounds like you got some trash in the carb when you took it apart. I don't see how going to larger jets is going to give you the flat spot just described. Sounds more like accelerator pump trouble/trash in the carb.

Does the truck have a lumpier idle now? If it does try removing the idle mixture screws and blowing some carb cleaner through them, blow some through all the air bleeds too. Might save you some trouble if you try that first.

If you take it apart, check the float level too. Does it seem more cold natured now?
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