thermal effects of combustion chamber

[Talltom]

One last try. Looking for somebody to bite  on the discussion of aluminum
pistons,
valves, ceramic piston tops or coatings with respect to fuel and ignition
requirements.
I have an 84 jag with aluminum heads, 11.5-1 compression(factory) that went
thru 
emmissions with 20 hydrocarbons and no CO. It's a completly stock v-12, and
a dog.
It does not ping on regular fuel. I have a 54 cornbinder with a turbocharged
500 cadilac eng. that pings on the same fuel at 9in. vacuum(it idles at 12)
Cadilacs have been famous for being detonators but the combustion chamber looks
reasonable to me.(Reassuring huh?) Yes I've played all the timing games. My
question is 
could the difference in thermal conductivity between aluminum and cast iron
and or
inadequate coolant circulation in the heads be the cause? If heads have hot
spots
does anybody with an oz or two more IQ than me have any suggestions as to
how to eleviate the problem? Yes I have thought of making like a canibal and
drilling out
the coolant holes in the bottom of the headgasket, but this seems just a
little to 
close to neanderthal for me even. I would like to modify the cooling somehow
so that
it could take a 30 minute full throttle blast.(without nitrous)

P.S. For you guys complaining about 12 mpg, I've got a 5.00-1 diff, and 27"
tires
behind a turboed 500 caddy, without an overdrive tranny. I'd be elated to bring
it up to 6.