I own a 4.3L OMC cobra V6 with a Prestolite (no points) electronic iginition system. changed plugs/ wires/ dist. cap/ rotor/ iginition coil/ fuel filter/ sparyed carb cleaner into the Holley 2 bbl carb/ been using 89 octane fuel. <br /><br />Motor was running on, adjusted the idle screw and air/fuel mixture on carb. this stopped the run-on, probably due to it running too rich at idle speed.<br /><br />Check timing, running 6 degrees BTDC.<br /><br />Motor gives a popcorn type sound when running 20-30mph. Sound might be coming from the exhaust? Runs great at idle and doesn't give off pop-corn sound when revving motor in idle.<br /><br />Also have problem with powertrim when running at high speeds. When powertrim is adjusted at high speeds seems as though the motor loses power and bogs down. Maybe a short somewhere?<br /><br />Any thoughts?
