Tractor Repair: Loud Knocking In Tractor Engine, ford 8n tractor, spark plug wires

Question
Hi, I have a 1948 Ford 8N tractor that started knocking very loudly all of a sudden.  It seems to be coming from the engine area. It knocks even at idle (but not as loud).  While idling, I removed the spark plug wires from each plug one at a time. When removing 3 of the 4, the tractor would run noticeably rougher, obviously missing on the cyclinder missing the plug wire.  However, while removing the 4th plug wire, the tractor did not run any differently with or without the plug wire attached.  (Not sure what that means or if related to the knocking). Anyway, any ideas what I might be facing?  Thanks.

Answer
Randy sounds like it could be a big end bearing or a gudgeon pin bush may be crook the way you checked it tells me this could be the problem.
You will need to drop the sump off the engine so you can check the bearing and pin bush from under the engine.

I would not continue to use the machine because you will destroy the engine Randy check it out and let me know what you find with it matey.


                Kind Regards Danny Last