strange noise

[twinockchef]

I cannot figure out what this noise is?
It is a very high pitched rattling emitting from the engine intake manifold. At first, I believed it was the timing chain but I do not hear the noise from inside the valve cover. The noise is always there. No matter what speed I drive at.
Is it the valves hitting the cylinders? I have adjusted the valve gaps twice.
Or is it that the engine is out of sync. The engine does not run well, at all, when the timing is dead on, 8 ATDC, but it runs better at around 24 ATDC, sill not great. Could it be that the cam shaft and/or injection pump are not lined up properly?
The noise and the poor engine preformance are driving me crazy.

[250 Coupe]

First thought on the noise is the bimetal spring driven intake manifold heating thingys whose name completely escapes me but further thought says it should change with RPM.

As for the engine being out of sync, I once put a head that I thought was a direct replacement on my 1970 250/8. It bolted right on, all passages lined up and the intake/exhaust matched perfectly. What didn't match was the cam timing. No matter what I did, it was always half a link off. I don't know how much that would affect things but that engine never ran quite right.

Michael