ok my friend has this 78 van with a 350 and it keeps poping i cannot figure out what it is its only does it when you get on the gas. i replace the cap rotor wires and plugs i also took off the valve covers and made sure it was all ok in there. did a compression test and all the pistions were between 110-120 it has a newer carb, any suggestions? tia

 

check the carb and make sure the floats are operating correctly

 

check your advance canister... see if you take vaccum off of it... if it stops popping