I just put 1968 #62 heads on my 1962 389 with a 1965 TriPower intake . I opened the chambers up a little to drop the compression even more. The 389 pinged badl on 93 octane gas. I had all the parts necessary to do the swap so I figured it was an easy way to cure the problem. It had a "066" replacement cam so valve clearance was not a problem. It went from pinging on 93 octane to running well on a mix of 89 and 93 octane gas.
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