Valve noise on startup only?

I don't know of anything to clean the lifters, but it definitely sounds liek they are just bleeding off and taking a little while to pump up. What weight of oil do you run? If you run a thick oil and its cold out it can take longer for the lifter to pump up as the oil is harder to push into the lifter, thus the reason that it quiets up after the motor heats up the oil and thins it out.

For years peeps have been using Marvel Mystry Oil to free up stuck lifters. Seen it work many times on very sludged up motors.

however

You usually don't have probs like that if you change your oil & filter on a regular basis.

Grady

The lifters are bleeding down....

Depending on oil weight, it may be time for new ones....

How many miles are on the motor?

Joe

Chris,
I don't know if I'd trust those "flush" type solvents you put in your oil. I used that stuff once, and once I drained my oil, I found tons of garbage, that could've just been accumulating inside the engine, some of which appearing to look like brass? Last time I checked, anything gold looking was material from a heavily scored bearing, so I got lucky when the block cracked, and I tossed a junkyard engine in, instead of rebuilding the engine in there. More than likely, the two were completely unrelated, since several months had elapsed between using that particular product, and the block failing, but it still makes me weary of using it, after everything I had drained out.
Now on to the noise you're having, I agree that it's more than likely a lifter, and I'd do an oil change or two before I go tearing into the engine. With the luck I have, it'd end up being an exhaust leak or something, that closes up once the metal expands...