HH56 wrote:
Quote:

I still need to seal off the heater box and check for other leaks in the engine bay.

If you haven't done them already don't forget the rubber edge seals on the flapper valves for air vent shut off and heater shut off. The way Packard placed the intakes for the air vent tubes behind the grill, the vents are amazingly efficient in sucking in the exhaust from the car in front of you and can blow past a poor seal. Damaged cloth ducting on the vent tubes either leaking or partially slipping off at one end and leaving a gap is also another good source of engine fumes into the car.