The 3.9, 5.2 and 5.9 engines seem to respond well to the colder plugs. I do not
believe using a colder plug would cause pinging in any engine. the new aluminum
engines have very different heads and may not utilize that plug number properly
because of a different electrode length. Does anyone know if the stock plug for
a 4.7 is the same as the stock plug for the cast iron magnum engines? There may
be a better than stock plug for the 4.7 but it may not be the 3923.
> o.k....... what's the deal i have a y2k 4.7 L 5spd with 3.92's posi. i've
> been running bosch platinum's #fr8lpx. ran a 9.01best at 71.09mph in 1/8th
> mile. after this afternoon(putting in 3923's with .040 gap) i run a 9.058
> best at71.53 mph in 1/8th. but on the way home cruising 65 mph in 4th gear i
> TROMP the gas and get detonation. i didn't have that before. the times we're
> best out of 8 passes, 1 week apart at same outside temp. please explain this
> maybe i'm not understanding. not hearing or feeling much difference, but
> HATE the detonation.
>
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