I wonder if you had your carburetor rebuilt before the prevalence of ethanol. I had a terrific rebuild done a number of years back on my '58 Chev carb, but then along came 10% ethanol and it ate the rubber parts in the carb - including the accelerator pump. I had the same coughing, backfiring you are having. The only solution was another rebuild - this time with the blue rubber parts (withstands ethanol attack) and now it runs great. Check to see if you get a _strong_ squirt from the pump, and if you don't I'll bet that's your problem. BTW if you're into the carb anyway, you might like to try going up a size on your main jets to compensate for the ethanol as well. I did that on my '70 4-4-2 and the difference amazed me. I swear it gave me at least another 50 hp. Good Luck Keith Boonstra Holland, Michigan - bluesport62 wrote: > > > HI GANG. CAN ANYONE GIVE ME AN IDEA WHAT TO LOOK FOR. ON MY 62 SPORT > 383WHEN I PUNCH IT FROM A DEAD STOP IT BACKFIRES AND STUMBLES. I HAVE > DONE ALL THE NORMAL STUF. CARB WAS REBUILT BY AN EXPERT 40 YEARS IN > THE BUSINESS CHANGED PLUGS WIRES AND PLUGS HAVE MOPAR ELECTRICT > IGN.TIMEING IS SET AT 10 DEGREES.I KNOW IT SOUNDS EASY BUT I AM STUCK > ON THIS ONE.IS THERE ANYTHING I AM OVERLOOKING. 3000 MILES ON REBUILD. > THANKS . JOE LUCIANO HOWARD BEACH N.Y. > > [Non-text portions of this message have been removed] ------------------------------------ To send a message to this group, send an email to: Chrysler300@xxxxxxxxxxxxxxx For list server instructions, go to http://www.chrysler300club.com/yahoolist/inst.htm For archives go to http://www.forwardlook.net/300-archive/Yahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/Chrysler300/ <*> Your email settings: Individual Email | Traditional <*> To change settings online go to: http://groups.yahoo.com/group/Chrysler300/join (Yahoo! ID required) <*> To change settings via email: Chrysler300-digest@xxxxxxxxxxxxxxx Chrysler300-fullfeatured@xxxxxxxxxxxxxxx <*> To unsubscribe from this group, send an email to: Chrysler300-unsubscribe@xxxxxxxxxxxxxxx <*> Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/