morgan in ar
Member
I had some time to work on the old Chevy today. I took out all the plugs, hoping to cough out any debris in the cylinder...no change. No plugs appeared damaged. I bought a bore scope, but I couldn't see anything except for the reflection of the light on the camera on the back of the cylinder walls. I pulled the valve covers, and didn't notice any change in the sound, or see anything odd. Three pushrods weren't rotating, but nothing really loose. All valves appeared to be closing all the way. The knock seems to keep time with the valve train. It sounds kind of like a three cylinder Ford or Perkins, to keep it tractor related. Other than the knock, it is running smooth. I tried listening through a hose, and the sound is loudest behind the water pump, and inside the breather on the front of the intake manifold. Camshaft?, Maybe fuel pump lifter? Could be a coincidence, not related to the carb change. What next? Pull the intake?