I am struggling to figure out root cause on a slight tapping noise on my TR3A. The engine had not been run for over 30 years until last year. It has great compression and oil pressure, runs very strong. But under load, at about 2500 rpm and higher, it makes a slight tapping noise. You can make the sound come/go purely with throttle position while driving. We were able to re-create the sound while sitting still if you rev the engine quickly, it will make the sound as it ramps up in rpm. Then a friend listened with stethoscope, determined it was cylinder #3, we unplugged that cylinder and the tap went away. Thought maybe it was excessive carbon buildup, looked like a lot of carbon thru the plug hole. Tried Sea Foam spray in plug hole, soaked overnight, then sprayed through carbs - lots of smoke but when done it still makes the slight tapping noise.
Have already made mixture richer, checked timing, and switched to 92 octane fuel. None of these seem to really make a difference. Rocker clearances all look fine.
Any other ideas?
Have already made mixture richer, checked timing, and switched to 92 octane fuel. None of these seem to really make a difference. Rocker clearances all look fine.
Any other ideas?