Can't get 355 motor running right

I have a 88 chevy truck with a 355 motor, holley 650 carb, edelbrock intake, and glasspack exhaust. The carb has been rebuilt, and has the smallest jets, 66 I believe. We thought it was running way too rich because of the larger carb. Well going down the road the engine backfires out of the intake, at least I believe so, and makes a pinging sound. I dont know if it is running rich or lean, or what is going on. I know I have a small exhaust leak but I wouldn't think it would make such a difference. Anyone have any answers?

check for a blown diapham on the distributor vacuum advace. check the timing too sometimes if it's advanced too much you get an intake backfire. you might have a bad/misadjusted valve also. i usually use a vacuum gage to figure out whats going on with carbs. this link deals with the diagnosis from a vacuum gage. good luck!!http://users.bigpond.net.au/ergoff/vac1.htm :smokin: