[FC] Its Backfiring

[corvanatics@corvair.org]

driving to work this morning, and the 'brier backfired a few times as i let off the gas, only seems to happen when its cold 55-60 degrees in southern ca

currently have the lower shrouds off, and i think the timing may be a little high @14-16 degrees

will check timing tonite and get lower shrouds back on

does anyone have suggestions on what else to check, plugs and wires are new

also what is correct timing for 110/4 speed, and prefer cheap gas not premium

thanks in advance to all

keith graham