& > I have gone one heat range colder on the spark plugs and to the 180
& > thermostat and the pinging is STILL there under prolonged hard
& > accelleration (2-3seconds+). I just throw in 2-3 gallons 105 octane
&
& I did not know that plugs had heat ranges. Does this mean they do not
& get as hot? How do you tell what the heat range is? Please excuse my
& anoying questions but this is news to me :-]
So what temperature is the stock thermostat??
Spark plug heat ranges are determined by the length of the insulator
before it meets the body of the spark plug. When looking at the underside
of the plug a hotter plug will have a deeper recess between the center
electrode insulator and the plug body. The center electrode is cooled in
part by the heat traveling through the insulator to the body of the plug.
The center electrode will not stick out any more or less, but the
insulator for the center electrode will have a different taper to control
how far down into the plug the insulator joins the outer plug body.
If the plug is too hot the engine will ping and/or self destruct. If the
plug is too cold, the plug will get fouled and quit sparking. On older
engines with an oil consumption problem going to hotter plugs can help
prevent plug fouling. A colder plug will only prevent pinging if the
pinging is caused by too much retained heat. If it is pinging because the
spark is too advanced then I wouldn't expect a colder plug to help.
The number on the spark plug indicates the heat range. Some companies use
higher numbers for higher temperature plugs (Champion, Bosch, Autolite).
Some companies number the opposite way: lower number=hotter (NGK, ND,
Accel). I don't know about AC. I don't care about Splitfire. I haven't
experimented in the Dak, but I'd recommend NGK or Autolite in general.
The letters indicate thread sizes, electrode type and length, and other
such stuff. The number is the heat range. Each company uses their own
scale for heat ranges, and one increment heat range is not consistant from
company to company, or even from one step to the next within a given
companies product. My table does show that Accel and NGK heat ranges
match up, and they use the same suffixes, so I guess we know who makes
Accel spark plugs now.
Frank Ball 1UR-M frankb@sr.hp.com
Hewlett-Packard (707) 794-4168 work
1212 Valley House Drive (707) 794-3038 fax
Rohnert Park CA 94928-4999 (707) 538-3693 home
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