Theo,
The parameter that directly determines the spark voltage is the spark plug
gap. Back in the '70's the auto manufacturers went to very large gaps -
.070"-.090" - and consequently had to increase the cap size and make other
improvements in voltage standoff capacity. I'm not sure what gap is normal
these days, but bigger is better to a certain extent at least. I think you
will see that MSD recommends around 0.055" or so, depending on compression
ratio. For quite a while I ran an MSD with a standard Ford dual-point
distributor with 0.055" plug gap and never had a problem. This was with a
pretty high compression motor BTW. I think a good set of 7 mm wires will
work just fine too, in case you are after that "stock" look.
Good luck,
Bob
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