Drop the ignition timing back a few degrees and see if the rattle goes away. It sounds like you're getting a preignition/detonation situation going on, which can be very destructive to engine parts, particularly pistons.
Jerry


"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
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