Anonymous asked in Cars & TransportationCar MakesChevrolet · 1 decade ago

V-8 chevrolet caprice 305 4 bbl Rough idling?

I have a chevy caprice 1986 and ive done quite a tune up on it like changing the fuel filter, air filter , spark plugs with correct gapping , adding stp fuel system cleaner and cleaning the carburator. But still it idle rough at about 650 rpm all the way to 1000 rpm and its slugish and burping when taking oh a red light.

any sugestion carb adjustment , idle adjustment , wire , disrtibutor ??

5 Answers

  • 1 decade ago
    Favorite Answer

    find a tune up check list and follow it step by step in the correct order. chilton manual parts store.

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  • 1 decade ago

    sounds like the carb's idle mixture screws needs adjusting and maybe the timing

    Put a vac gauge on engine, turn 1 idle mixture screw at a time watching the vac gauhe, stop turning when you get the highest vac reading you can get. Then do other screw same way

    check the mech. advance in dizzy (parts under rotor button) If gummed up, real rusty, broke springs, etc the timing will not advance as rpm comes up

    check and set your timing. Around 4* BTDC would be a good starting point on that one. (check with vac advance line un hooked from dizzy and plugged off)

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  • 1 decade ago

    Sounds like you are on the right path, check the inside of the distributor for rust, that was a recent problem on my 5.7.

    Wires might be bad sometimes when they go bad you can pop the hood at night while the motor is running and see sparks jumping off the wires to your block or the closest ground.

    It does sound like the timing could be retarded, mark where it is and attempt turning it slightly counter clock-wise and if you here the valves rattle when you give it gas you have went to far.

    Your carb could also be out of adjustment or you could havvacuumccum leak.

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  • 1 decade ago

    monte's pretty good - I'd check your vacuum lines, and while you're at it, check and clean out your EGR - it will cause all sorts of evil if its sooted up.

    When you cleaned out the carb, did you mess with the adjustments? Also, did you replace your HEI's cap and rotor?

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  • monte
    Lv 6
    1 decade ago

    Sounds like a vacuum leak. Check all hoses for cracks, splits, or any other problems. Also check or replace the PCV.

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