[Bruce Compton, Canada]

Randy : BOB has a good suggestion with the MMO, but pour it down the carb after the engine has reached operating temp. Make sure you do this OUTSIDE, and pour it in while opening the throttle enough to keep the motor running till all the MMO is in. Let it stall the engine then leave it sit for a few hours before starting it again ( don't forget to turn off the ignition). I also would not eliminate the timing gears as a potential cause as even many parts suppliers still don't know the reason for the tooth pitch angle difference between the early and late gear sets, as they totally interchange. If this is the problem, it would take quite a few miles for the wear on the inside of the timing cover to increase to the point that it would allow any noise. However, now I'm guessing that you will find your noise when you run the engine with the belts off. One last guess though, is the tube over the fuel pump push rod. I've had these come out of the fuel pump stand ( press fit) and fall down so that the umbrella on the push rod hits the bottom of the tube causing a noise that sounds remarkably like a loose valve. Again, Good luck : Bruce.