Maybe they used a thin break-in oil, and the timing is a little too advanced causing some slight detonation.
Check the valve adjustment/ lifter preload, change the oil and filter(cut open the oil filter and see what it's caught) and double check the timing. Let us know what the initial timing is set at and the what the total timing is too.
Last edited by jbc426; 03/28/12 03:17 PM.
1970 Plymouth 'Cuda #'s 440-6(block in storage)currently 493" 6 pack, Shaker, 5 speed Passon, 4.10's
1968 Plymouth Barracuda Convertible 408 Magnum EFI with 4 speed automatic overdrive, 3800 stall lock-up converter and 4.30's (closest thing to an automatic 5 speed going)
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