Posted by minerva on July 30, 2001 at 00:52:01:

In Reply to: 65 Series IIa Compression Ratio & Spark Plugs posted by hc carter on July 27, 2001 at 21:50:04:

The compression ratio doesn't matter, what matters is how the sparkplugs workk under the conditions they they are being used. Fi nd a good auto parts store and ask for a Champion (not my favorite plug, however theymake good diagnostic charts for the rednecks) and compare how your plugs look with how they SHOULD look. Change up or down in heat ranges as required.

As a practical matter, the best performing sparkplugs are the Platinum fine wire type, not the multi-ground massive electrode type.

Also, with any old vehicle that may have been worked on, the compression ratio may have been changed by head miling, overbore, high compression pistons, stroker crankshafts.

As a rule of thumb, higher compression ratios, bigger carburetters, and free flowing exhaust requires colder 'or harder' sparkplugs, as does working the engine harder by heavy loads, high speeds, or trailer towing.

Low speeds, cold or no thermostats, lots of idling usually requires hotter or 'softer' sparkplugs.

Plugs that are 'fluffy' may be as a result of too much choking or bad ignition wires. Almost all wires sold today are 'resistance' type, and usually don't even contain wire. The current is carried by a carbon/graphite core to reduce radio interference.

As thes wires age they get stiff and the core separates and the ability to carry current decreases. While they can be measured, if they are a few years old it is just as wel to replace them with a better grade. I have two favorites, Sorensen 'Mono Mag' and believe it or not, genuine Bosch wires made for 6 volt VW's.

The mono mag wires are made of a stainless wire wound into a fine 'spring' of varying pitch, which suppresses electromagnetic radiation because the varying pitch makers for a bad 'antenna'. Unfortunately, the sets are custom made, and unless you get a very good and helpful parts person they won't take ther time to either find and/or make you a set that fits. The easy alternative is to get the VW set. They are made of real copper wire, with soldered ends on the distribtor end, and the required restince built into the sparkplug terminals. The terminalssimply unscrew out of the end of the wires, which can then be cut to the proper length and the resistor screwed back on. The only requirement is that the plugs you use have removeable tops, the VW connectors have a spring clip that fits over the screw top of the plugs.

IMPORTANT!!! Fittment of plugs that are of a too 'hot' heat range will quite often cause preignition and piston or head gasket failure. If there is an oiling or valve problem, fit the problem. (Putting in hot plugs is equalivent of the reason lepers lose their fingers)

I hope this helps, if you have questions contact me at jminerva@ntelos.net.

Jminerva