carb backfire

the other day i was letting my jeep wrangler warm up it has a weber 32/36 carb and a hei distributor ,258 cid motor,when all the sudden it shut off and backfired thru the carb.i tried to start it but it would turn over make a funny noise out the exhaust and backfire thru the carb.i checked the dist.to see if the shaft might have broken it was alright.check tdc on compression stroke rotor was pointing to number 1 piston.i changed the timing chain and gears lined up dots with number one up on compression stroke,when i tried to start it it turned over and then backfired thru carb.does anyone have any ideas what is wrong?

I would check the compression to ensure that you did not mess up a valve.