Swaped 350 Chevy backfires ,need some idea's help

Swaped 350 Chevy backfires ,need some idea\'s help

I swaped a 350 chevy in to my CJ7 and it backfires a lot,some times real hard. I picked the motor up at a junk yard,the motor sounded good, I put it in and put new plugs,and wires,and distrubuter cap and router cap. Wired all plug wires up with a chiltons book. The motor sat in my shop for 6 months and when I went to start it I had to turn the distrubuter cap to get it to run, it would backfire off and on,but all the vacume hoses were off,so I thought that it would go a way after I had them hooked up. I drove it a ways and it only backfired after I got on it hard. I had it rev real high and I tryed to bump the gas to get it to rev down and it would not come down so I shut it off and it backfired real hard and it has run like cr4p from then on. I had a guy over to help with the vacume hose's and we cant keep it from backfireing hard. I think it only backfired hard 2 times. Could it be getting to much gas,you could smell the gas in the exaust. Would the carb make it backfire like this. The guy that is helping me thinks that it could be valve's,and thinks it is on one side of the motor. Help wife is pi$$ed off at me. Thanks.