Ive been going through my H pretty thoroughly, and I can’t seem to correct the spit/sputter misfiring that happens at lower RPM’s. If at idle, the engine runs extremely rough, and smoothes out as RPM’s increase, until completley smooth at full RPM. The engine smoothes out a bit by pulling the choke halfway out, and is also considerably smoother under a light load, such as 5th gear. Ive pulled off spark plug wires one at a time and have determined the misfiring is erratic, or not specific to one cylinder.
Ive replaced the manifold gaskets, rebuilt carb(checked float multiple times), rebuilt distributor(coil, spark plugs, plug wires, condenser, new points set correctly. NO new cap.) Also timed the valves and replaced the sediment bowl and added an inline fuel filter.
Heres my thoughts, and I wonder if someone can confirm one or both of these as the issue.
1. The new inline filter has air trapped inside that doesn’t seem to get sucked out. Could a leak in the fuel line cause too much air to make its way to the cylinders, causing it to run rough?
2. The manifold mating surface to the block was corroded around the exhaust ports, could exhaust me making its way into the intake port(s)?
As of now, I plan on buying a brand new manifold. Many thanks for any help you fellas can provide.