" . . voice cover . . . " ? - fumes from the slits/openings (exhaust smells?)?
We knew what you meant:
" . . . to minimize the strong exhaust smell I looked at the cowl vent drain line that ends right above the voice cover . . . "
valve cover
Clutching at straws:
#1: Is your road draft tube clear?
#2: Get a nylon tubing connector and a 4' length of rubber vent hose. Extent the vent hose to exit under the starter. I do this to allow rainwater from the vent to exit under the truck, rather than over the open-slitted valve cover (1955-1st and earlier). That hose-extension should also result in air being sucked out the hose under the truck, when moving.
