#4 and 6 plugs might be fouled or bad. Tight lash will cause popping but why just those two? Timing, crossed wires, cracked or carbon in dist cap, carb/intake manifold leaks cause popping too.(vaccum check for a steady needle)


1951 Ply Concord truck
1954 Nash Rambler 2 dr
1955 Nash Rambler Farina