carbureator backfire

[Guest]

437000

i really need some expert advice....i got an 84 jeep cj7 and have just completed an overhaul of its 258 inline 6 and the timing has been set correctly and the vehicle runs great and idles fine but after about 3to4 times of hitting the throttle the carb is back firing (out)through the top.spitting gas.it has a carter 2 barrel carb and the idle and gas mixtures have been set.any tech info if anyone has encountered this or advice would be great.this is my last ditch effort to find out what would possibly cause this.holt.

 

[Guest]

438000

From my experience, backfire is either timing, too lean or in some weird instances a bad intake valve, as in not seating properly. I'd suggest a go over. Check your hoses for air leaks which can lean out your mixture. Recheck your timing. Compression test may help with the valve question. Is this happening only with the air cleaner off or both off and on?

 

[Guest]

439000

thanks ill check and trouble shoot a while.

 

[MORGSTER]

440000

Check out this site, it might have some useful information. http://www.off-road.com/jeep/tech/258bbd/index.htm

 

[sillsmack]

441000

Remember,

Backfire through carb = timing advanced

Backfire through exhaust = timing retarded

As all engines have timing set a couple of degrees advanced, backfire through carb CAN occur with lean mix