[Tom Wesenberg]

Hot air pipe is the steel pipe that carries heat from the exhaust manifold to the air cleaner, such as you would find on 70's and 80's cars. Hot air pipe on a Model A probably means the connection between an exhaust heater and the firewall.

The cam gear has just a dimple, such as a drill bit would make about 1/8" deep, or a hair less. I've never had to put a point of the timing pin.

I use a vacuum gauge when it's needed, if the manifold has a vacuum port.