I checked out http:\\www.autolite.com and found the following numbers for
Autolite plugs for 2.5L engine:
APP985 a double platinum plug with a copper core.
AP985 a platinum plug
985 a standard plug
All plugs have a heat range of D10. I would assume a heat range of D9
would be the next colder plug. Could not fined a number for a D9 heat range
plug.
Regarding heat ranges, I pulled this off the Autolite site about racing
plugs. Some of you know this information already, but for those of us who
don't...
"Spark Plug: Heat Range Facts
Typically, engines which are stock or are only slightly modified, can use
the original equipment (OE) recommended spark plug.
Racing Modified Engines- Generally, any engine modification that alters the
overall compression ratio of the engine will involve spark plug selection
issues. One thing to consider is heat range. The heat range of the spark
plug determines how much heat the spark plug is capable of removing from
the combustion chamber.
The heat range of the spark plug does not increase or decrease horsepower.
It changes the temperature of the tip of the spark plug. If the heat range
is too cold, the deposits will not burn off the tip and the spark plug will
foul. If the spark plug heat range is too hot, pre-ignition can occur.
A switch in heat range of the spark plug will change the temperature of the
spark plug tip by 70-120 degrees.
If you are unsure of the correct heat range to use, always start with a
colder spark plug. If the plug is too cold, the plug will eventually foul
and a misfire will occur. This will not hurt the engine. Unfortunately,
though, if a spark plug that is too hot is inadvertently chosen,
preignition and detonation can severely damage your engine. Don't go to a
hotter heat range unless you've consulted your engine experts.
As there are many different ways to modify your engine for racing
applications, we can't tell you here which specific spark plug to use. If
you have made modifications to your engine, you should refer to your
component manufacturer's specifications and/or contact the experts at
Honeywell at www.autolite.com."
-- Miles Harris III Simi Valley, CA 01 Silver Dakota CC Sport, 2.5L, 5speed 01 Gold Saturn SC1 (3 door coupe) 1.9L SOC, 4speed auto http://www.spikesautos.homestead.com/Dak1.html Profile: http://www.twistedbits.net/WWWProfile/dakota/PfCA4R1zO470w"Alek Benedict" <alek@earthling.net> wrote in article <KHEPKNIADOPGGADEMIKLIEMNCGAA.alek@earthling.net>... > : If I understand posting on list correctly, the 3923 is a colder plug than > : the stock plug or what is called out for by Autolite (sorry don't have the > : stock number). With that logic in mind (and please fell free to > : correct me) > : the thing to do is find the Autolite plug for the 2.5L engine and > : than find > : the next colder plug in that size range and put it in the truck. > > If it's any help, and I don't expect it to be, the little spark plug/wire > reference computer and Wal-Mart said the right Autolites for the 2.5L are > the 65s. I'd *guess* a colder plug would be a 64? > > -- > Alek Benedict with a techno beat. > alek@earthling.net > > 1993 Dodge Dakota Sport [2.5L/5spd] > >
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