[George Bongert]

Greetings!

I agree with Bill. It is most likely valve train noise. I heard nothing to suggest that there is anything wrong with the lower end of the engine. The engine itself appears to be idling roughly, and I would definitely check valve adjustment, and timing among other things, including the idle speed mixture adjustment. When I owned my truck, I had my 305 idling so smooth that you could place an orange juice glass half full of water on top of the air cleaner, and barely see a ripple in the water. Yours should be idling just as smoothly. The engine appears to be extremely clean, suggesting that the previous owner may have replaced the valve cover gaskets, and may have made an attempt at adjusting the valves. The lack of power that you describe can come from valve adjustments being too tight, thereby holding valves, especially the exhaust valves, partially open when they should not be, which could very well contribute to loss of power, and to the rough idling of the engine that I observed in your video. Hope this helps, and good luck! Sometimes it takes a little time to chase down those mechanical Gremlins, especially when you don't know what the mechanical aptitude of the previous owner(s) was!