fleajr Posted November 22, 2016 Share Posted November 22, 2016 Why does my 1922 Dodge backfire through the muffler while driving acclerating then quickly decelerate the throttle? I advanced and retarded the spark lever when this happens with no change. I also had my 12 volt starter/ generator rebuild. Upon idling the ammeter shows a charge of + 4-6 and when accelerating needle moves all the way over on the charg side of the ammeter. At one end of the generator are 2 adjustment screws so we turned the screw all the way down, but it would not turn apparently low enough to get the ammeter rate to center 0 . The brushes look to correctly installed. Any thoughts? Link to comment Share on other sites More sharing options...
61polara Posted November 22, 2016 Share Posted November 22, 2016 Your backfiring sounds typical of burned exhaust valves. When you decelerate quickly, the exhaust is still fairly rich with gas and the burned valves will allow the spark to flash back into the exhaust. Link to comment Share on other sites More sharing options...
jan arnett (2) Posted November 22, 2016 Share Posted November 22, 2016 I would also check the timing. Link to comment Share on other sites More sharing options...
Guest 1935 Dodge Van Posted November 22, 2016 Share Posted November 22, 2016 1922 Dodges are not in my repair history but your generator must show a slight discharge at idle. This is because the generator has been disconnected from your battery by the cutout. Yours does not seem to be doing that. Are your cutout points stuck? Later generators which I am familiar with have a 3rd brush that is slid back and forth to set the top current output of the generator. Usually 20 amps although I set mine to 15 amps and just drive further each time I use the vehicle. Less wear and tear on the generator and the battery. Your generator is working and the battery must be good or the engine wouldn't start.Look for poor grounding at the battery and at the engine to ground ie the return path to the battery ground cable. Sometimes on old cars the build of rust etc. causes a poor grounding between engine electrics and the battery/generator circuit. A good cure is a flex ground cable from engine bell housing and frame nearest the battery. Which I take it is below the front seat? The 'farting' as mentioned could be carbon built up on the vales and piston tops. A good upper engine cleaner the kind you pour down the carb whilst the engine is running must cure it. My 2cents. Link to comment Share on other sites More sharing options...
22touring Posted November 24, 2016 Share Posted November 24, 2016 Backfiring can also be caused by running too lean, which in turn is caused by things like vacuum leaks, lack of fuel delivery, keeping the carburetor inlet vent closed during hot weather or the carburetor metering rack not being adjusted correctly. Link to comment Share on other sites More sharing options...
mikewest Posted November 24, 2016 Share Posted November 24, 2016 22touring is correct - car running TOO LEAN open up the mixture Link to comment Share on other sites More sharing options...
24 Roadster Posted November 25, 2016 Share Posted November 25, 2016 Here is a wild backfiring case. A few years ago I was in a parade and my 24 Roadster started backfiring. It would run OK for a while then start poping and backfiring and doing all sort of crazy things. I was hauling the mayor so not a good time for this to happen. Somehow I got through the parade and loaded the car on a trailer. When I got to my shop since it was an electrical problem I disconnected the battery. Then I noticed a melted battery cable. The cable was rubbing against the brake or clutch connections and shorting out. This is why it only happened when I stopped. New battery cable and different routing and I was back on the road. Just lucky I saw this before I looked for days for the problem. I would have never thought to look at the battery cable for the problem. Of course everyone in town still kids me about the noise coming out of the Roadster. Sounded like we were being attacked. Link to comment Share on other sites More sharing options...
dwollam Posted November 25, 2016 Share Posted November 25, 2016 Funny, but my 22 DB Screenside has backfired when backing off the throttle for many years. Engine completely rebuilt, stainless valves, new guides, springs, everything. Tried different carbs, different exhaust, no exhaust, timing, fuel mixture, you name it. Usually it is when I am heavy on the throttle on the highway to my house and trying to stay out of the way of traffic. Got her wound out pretty good and then snap the throttle shut and it will explode through the exhaust with a huge bang! If I back off the throttle slowly it usually won't pop. I've given up! Link to comment Share on other sites More sharing options...
22touring Posted November 25, 2016 Share Posted November 25, 2016 I've noticed that when a 4-cylinder DB motor has very good compression, even a slightly worn carburetor throttle shaft will make it backfire on deceleration. Link to comment Share on other sites More sharing options...
dwollam Posted November 28, 2016 Share Posted November 28, 2016 I can believe that. Mine was and is still in very good shape engine wise. For sure WAS NOT before I rebuilt it! Don't really remember back fires before that but it might have. Been too many years now. Pretty sure most all my carbs have got to be sloppy. Link to comment Share on other sites More sharing options...
platt-deutsch Posted November 28, 2016 Share Posted November 28, 2016 15 to 20 amps charge rate may be ok for 6 volt but on these 12 volt systems 4 to 6 amps is adequate. As to backfiring, Check the inside of the Dist. Cap for tracking. Link to comment Share on other sites More sharing options...
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