I bought a 1952 International Harvester Metro a few months ago with the original motor. The vehicle sat unused for a few years. I replaced the main gaskets, the timing was not touched, replaced spark plugs, coils, points, condenser, I had the upright carburetor restored, replaced the gasoline filter, water pump, gas pump, I calibrated the valves. The engine cranks, but doesn't start. There's a spark. I tried using starter spray, but nothing. Any advice?