Last week I had the timing chain and sprockets replaced on the 360 in my 71 Fury at a local shop. At the same time the water pump and fuel pump were replaced. I picked it up on a warm afternoon, about 85, and noticed on the way home pinging under light throttle application that went away with more throttle. I was close enough to home when it started that I didn't go back to the shop but called later and the owner told me he didn't touch the distributor or carburetor. I put some Seafoam in the gas and sprayed a can into the carb mouth which helped but didn't completely solve the issue. I was thinking maybe the new timing chain would eliminate any slop from wear on the old chain which had worn nylon teeth on the sprockets. Could the new chain advance the ignition timing slightly if it was correctly installed? Today I decided to remove the air filter assembly to check all of the vacuum lines to see if any were loose. I pushed them all down tight and adjusted the curb idle down a bit as it was a bit fast. I reassembled everything and test drove the car and the ping is almost completely gone. Ambient temperature is in the 80s again today. Any thoughts? Could one of the vacuum lines have been leaking slightly causing a too lean mixture in turn causing engine ping? Car has 87,000 miles and is pretty much stock.