I have a 52 B3B that was overhauled and seems to run fine at idle and when increasing rpm in the shop. When I drive it on the road it does not want to go over 30 mph and begins missing and sputtering some popping thru the carb. the plugs are new, firing order is correct, plug wires new, distributor cap not cracked. I have converted to 12V but did not change the points. The points do have a frosting around them. I do not have a ballast resistor to the coil. I am sure the valve timing is correct but have not checked it. Any help would be appreciated. Thanks Larry