It's not uncommon to convert an engine into an air compressor. Thousands of Model A Fords were modified like that to run jackhammers by running the engine on two cylinders and compressing air with the other two, but it required a special cylinder head. I've also seen a 302 Ford V8, and several flathead Ford V8's converted that way. It would require a bunch of modifications other than just disabling a valve to get fresh air, instead of an explosive fuel/air mixture into the tires! Nothing like launching a John Deere into orbit with one little spark!
Several years ago, I had a tire inflator that was installed in place of a spark plug to pump air, but it had a rubber bladder and a one-way check valve, and it didn't put the fuel mix into the air hose. It just put the unburned idle mixture for that cylinder down the exhaust pipe.
Jerry
