Have you tried just pulling a few degrees out?

I have one 440 (10.12 comp) that would faintly rattle on a hot humid day at 37-38 total. Pulled it back to 34 and it was OK.


72 RR, Pump gas 440, 452s, 3800 lbs, Corked, ET Radials,. 11.33@117.72. Same car, bone stock 346s, 9.5 comp, baby solid. 12.24@110.