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Actually your cranking compression tells the story. Challenger1 has a measured 10.4/165-170 psi and you're way higher than that on the psi plus I'm assuming no quench so I would say no way on pump gas. As you know pinging is extremely damaging & must be avoided at all costs.



I get what you're saying, but why on earth was this engine able to run on 91 without pinging then? There were no signs of detonation that I could see. The plugs look fine, albeit a bit on the rich side.

Nothing like that is a given. There are too many variables that will
can effect the end result.




Cam timing can affect cranking psi with the same compression.