Guest Adil Posted March 30, 2015 Share Posted March 30, 2015 Hello All,I have a 1929 ChevAC 6 Cylinder. The car was converted to 12V before I purchased the car.Starts ok, idles fine when cold. drives good out of driveway for about 2 blocks. After 2 blocks, it starts to miss, intermittent backfire and popping out of carb, no power and stalls. hard time to start, when it does start, it backfires and pops out of carb and won't idle. It also has a weak spark. I changed plugs, coil with external ballast, condensor, points, rotor, cap, wires, plugs and ignition switch. I also re-adjusted valve clearance as per manual. Driving me batty trying to figure this out. Any one have any ideas?ThanksAdil Link to comment Share on other sites More sharing options...
Pete O Posted March 30, 2015 Share Posted March 30, 2015 Carburetor icing? Link to comment Share on other sites More sharing options...
GLong Posted March 31, 2015 Share Posted March 31, 2015 Do you have the manual choke pushed all the way off when you leave the driveway? Or are you slowly pushing in on the choke knob? If this was a later car with an automatic choke I'd say the two blocks is long enough for the choke to have opened completely, and the carb's main jets are dirty and the carb is running way too lean, hence the backfiring. Assuming you have a manual choke, pull the knob out part way, providing about half choke.. see if some choke makes any difference in the poor running.Just a thought, GLong Link to comment Share on other sites More sharing options...
Guest Posted March 31, 2015 Share Posted March 31, 2015 Popping back through the carb usually indicates a lean mixture. It certainly could be icing. Around 31 to 35 degrees my Pontiac will ice up if the humidity is at all high. Also could be dirt in the primary jet.Good Luck Link to comment Share on other sites More sharing options...
Roger Zimmermann Posted April 1, 2015 Share Posted April 1, 2015 Or the engine is sucking air from the wrong place: bad gasket at the intake manifold or the intake is warped; gasket at the base of carb. Link to comment Share on other sites More sharing options...
JACK M Posted April 1, 2015 Share Posted April 1, 2015 You might experiment with different points gap. Link to comment Share on other sites More sharing options...
Phillip Robinson Posted April 8, 2015 Share Posted April 8, 2015 I have the same car but not any issues with the motor. After I start it with the choke out about 1/2 inch, about 10 seconds later I start to push it in. In 200 feet the choke is all the way in. Phil Link to comment Share on other sites More sharing options...
Spinneyhill Posted April 8, 2015 Share Posted April 8, 2015 Sounds like what my Dodge does in cool humid weather until warm. Try idling for 5 mins, shut down, wait for 5 mins, then start up again. It might just drive away good as gold.Does it have a manifold heat riser valve and if so do you use it? Link to comment Share on other sites More sharing options...
rhb1999 Posted April 10, 2015 Share Posted April 10, 2015 An intake valve stuck open when the plug fires, causing it to backfire though the carb? Link to comment Share on other sites More sharing options...
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