Rolling along up on plane, next thing I hear-feel is a miss, like running on 7 cylinders. Check the spark plug wires and distributor, checks out fine, oil pressure is fine and oil is golden and full. It will hardly idle and is "ticking" not "knocking". The engine "tick" sounds like it is coming from the top of engine. Motor has 300 hours on it.

Question: Do you think it is a broken valve spring?

Pull a valve cover. That should tell you a lot more. Mine was a bent push rod and a bad cam lobe.

ttt

I would check to see if the rotor is tight on the dist shaft first. then pull the valve cover. I spent a lot of money on the pair that I have and found that the rotor was loose, I locktited it and let it set over night like the book said and problem solved.

Thanks guys, for all the info, I will check the rotor!!

I would pull the valve covers, check the springs and rotate the engine to make sure everything looks ok before I ran it again.

If everything looks good then I would pull and inspect each spark plug and change the dist cap and rotor.

ttt

I would take it to a mechanic

Just pulled it apart, bad lifter on exhaust side of #3 cylinder. You can literally wiggled the rocker arm back and forth and hear a squishing noise, off comes the blower!

What brand lifters are you running?