Pinging like crazy

My 1.5 89 civic along with other problems has been pinging like crazy. I set the timing and that helped but, it seems to get worse and other times improves. When it is pinging my ears of, if I push the pedal almost to the floor, the pinging almost goes completely away while accelerating. However, once I go back to normal driving the pinging comes back. I'm thinking it has something to do with a vac. line somewhere. I had a 64 chevy that had a vacuum advance to advance the timing. Does this Civic have one too? If so how do I check it ? Where is it? and if not what do you people think is the problem?