Re: Distributors and advance curves - how many did Packard build?

Posted by Jack Vines On 2010/6/16 22:50:19

Autolite is the most commonly available spark plug and they have changed their nomenclature three times in the fifty years I've been buying plugs. Their 56 plug was one which worked well in Packard V8s, but recently it is showing as discontinued and they are trying to substitute the 66, which is a hotter plug

To add to the confusion, with US plugs, as the numbers get larger, the plug heat range gets hotter.

With Bosch and NGK, as the numbers get larger, the heat range gets colder.

Throw in the platinum, platinum-plus, iridium and iridium-platinum plug variations, none of which really apply to our cars and most of what comes up in searches is all over the map. The sparkplug.com site will give heat ranges from #5 to #14 as interchangeable. NOT!

thnx, jack vines