That is probably not a valve noise- - - -too deep of a sound, and the frequency is too fast. That's either a piston slap or a connecting rod knock. It will run a lot smoother if you plug off the vacuum leak from the tube sticking out of the intake manifold below the carburetor.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!