Have a 302 w/ a holy 650 carb just got tuned up, timing 8 deg advanced, points, new dist cap, plugs, wires, holly blue electric fuel pump. Car starts good, and has a strong idle. After the car is warmed up and was driven for about 15 minutes started to notice a 'popping' sound while driving around 55 @ 2k RPM. Not sure if it was comming from the tail pipes or carb though sounded like the rear end. The car had been sitting awhile because of cash probs. unfort did not have time to open the car up and see if it would bog down or poping sound would increase. Also, if I hit the gas @ a standstill I could run it all the way (6 ~ 7k) up and no backfire/pop. Only seemed to do it under load. Any ideas?!