Re: ? What is Hole for on top of exhaust manifold? On a 6 cyl 1941 19 series 110

Posted by HH56 On 2024/1/20 10:55:43

It looks like the end of the heat stove. That is a tube pressed into the exhaust manifold in such a way the hot exhaust gas surrounds and heats the tube. The bottom end of the stove should also be sticking out a slight amount but be crimped in such a way there is only a small orifice remaining. Placement of tube varied by engine and carburetor. Here is what one looked like in a later engine.


In operation, a length of 1/4" steel or copper tubing would have a snug push fit into the upper end of the tube. The other end of the tubing is connected to the automatic choke enclosure on the carb. When the engine starts, because of the orifice in the heat tube air flow is restricted so vacuum can only draw a small amount of air heated by the exhaust gasses up thru the tube. The heated air acts on a bimetal spring inside the choke housing. As the heat causes the bimetal spring tension to change it allows the choke to open when the engine reaches the temperature point where the choke is adjusted.