Help- lost power at freeway speeds, clackity noises

Just did an oil change and set the valves this morning.

.006, cold engine. VS 1900, about 800mi.

Everything checked out, went for a test spin at low speeds, then went out again and got on the express way.

After about 5mi, sudden change in engine tone, lost power, felt like it was missing, little louder clacking than usual.

Shut it down immediately, had it towed home.

Obviously, will check the valves again when its cool.

Any other suggestions?

I loosened my valve assemblies all the way out once, like a dummy, and when I put it back to a loose .000 ... I actually set the ends of a couple the pushrods against the lips of the cups on their rocker pieces.

Once it warmed up a bit, the pushrods bounced off of their precarious positions and made one HELL of a lot of noise.

I pussed out of trying again. I paid a guy, but asked him to show me what I did wrong. I also called Danny Piperato in a panic, but that's a horse of a different color.

I since found a happy place for the settings on my engine, too. It's happiest at .003, using standard rocker pieces and oval-port Bus heads. (I have a T-IV, not a T-I.)

You'll probably get out of this one alive, but you'll not really find out until you pop the valve covers again.

Good luck, amigo.

Wadda you think?

Valve lash adjustment lock nut/screw backed off and sitting in the valve cover?

Push rod no longer in contact with the socket on the rocker arm?

Snapped rocker arm?

Any/all of the above . . . ?

LOVE the simple fixes.

Paul, I had the same symptoms and when I pulled the valve covers I found that one of the little wire clips that holds the rockers in position on the rocker arm had failed and one rocker adjuster screw was no longer hitting the end of the valve, but the valve spring keeper beside it. There is a cure if this is your problem.

Thanks for the replies.

Won't know until I have time to dive back in, hopefully in the next couple of days.

Fingers crossed for something simple.