Greetings . . .

My experience is similar to Twisted and Bowtie's. I had 12:1 pistons in a 327 v-thingie. Cranking pressure was north of 200 psi on all cylinders. It ran fine on regular.

But I was running a stock cam and a stock jetted Rochester 4 barrel. So I think decreasing V.E. as RPM rose kept dynamic CR down to the point that it didn't ping.

Only problem I had with the setup was hot starting. The engine needed to cool down before the starter could cope with hot cranking pressures. With initial timing set to maximize vacuum it was impossible to start hot. Even with timing set slightly retarded from stock it was hard to start hot.

regards,
stock49

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