The GMC CCKW

Hi ...just wanting some suggestions from the brains trust. My 1943 open cab cckw seems to emit a lot of black /carbon emissions ... to the extent that it creates a watery black mark on the corrugated iron in my shed when I start it up ( I only have about a foot or so to spare on either side of the truck in my shed). Is this normal? Is it likely to be running too rich? or is this likely to be related to the oil bath air filter? Engine compression is good, doesnt seem to be excessive oil use.
comments welcome
regards
sixbysix

Black exhaust is usually an indication of incomplete combustion (such as one the engine is cold, choke in on and fuel mixture is rich.

When our CCKW is backed into the shed and the exhaust pipe is pointed at the wall, it leaves a black mark on statrt up on that side of the shed.

Cat Man