Here’s a letter that Half-Mast received from the field…
I’ve run into some trouble with carburetors on the 1/4-ton Willys’ got a batch of them to overhaul and after I’d cleaned them up and replaced all parts with new ones, they were put back on the vehicles. But they just wouldn’t idle. I checked them all over: the idle jet was clear and all passages free of dirt and lead accumulations, the economizer was free of all foreign matter, the floats were set at the specified level, and the metering rod adjusted to the proper operating length. I also checked for cracks in the base of the carburetor and the body, and I checked the rivet plugs. All was in order. Can you clear up the mystery? Another question is: What are the Welch plugs on the side of an engine block for and what’s their purpose.
There’s a lot of conditions in the engine that could prevent it from idling properly. But I’m gonna assume the engine idled all right before you overhauled the carburetor-and then I’m gonna suggest you check the throttle butterfly.
If you didn’t assemble the butterfly with the letter “C” facing the manifold and towards the port opening in the carburetor body at the air-adjusting screw, that ‘d be your difficulty. Because if you checked all the things you said you checked-the trouble is probably improper assembly of the parts.
The Welch plugs on the side of the engine block are simply to close up the holes made by the core sand legs when the block was cast at the foundry. And just because a lot of guys call them freeze-out plugs, don’ t think they’ll prevent cracking of a cylinder block when the water inside freezes solid -they won’t.