Anyone use Autolite XP-103 spark plugs?


Jul 31, 2003
i'm trying to find out what the heat range is on these things. Autolight says the heat range is 3, but im not sure what stock is for heat range. Anyone running these? I'm looking for plugs that are 2 heat ranges better than stock. I know the tr7ix are, but i cant find these locally; however, i can get XP103 plugs tomorrow. Can anyone help, i've searched and searched but i just got a headache from it. They seem so new that i cant find any info on them.
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Active Member
Aug 12, 2005
Clovis, CA
since you have a v2 blower you can use NGKtr6 plugs which are 2 step colder and AWESOME plugs for forced induction....way better than auto lites IMO


Jul 31, 2003
since you have a v2 blower you can use NGKtr6 plugs which are 2 step colder and AWESOME plugs for forced induction....way better than auto lites IMO
We'll those are only 1 step colder and im currently using those. I keep getting spark blowout and The car has been rugish with them. I replaced a couple of them, fixed the rushish ride, then 3kmiles more its back. I need a better spark plug and soon. I want the iridium because there a stronger plug. For some reason my engine does not like the TR6's I think there to hot for my temps. When it was 60-70 outside it was fine, but once we hit 100 here in cali it hasnt been driving right, and with out continuous hot weather its time to get a colder plug.

If there is any iridium plugs locally i can buy that is 2 steps colder i would prefer to do that. If im stuck buying online it'll be the TR7IX plugs, but that will take a week to get.

Any other recommendations?


New Member
Nov 6, 2005
just go to the parts store and ask for lightning plugs they are 2 heat ranges colder from factory.

the 103s in auto lites are only 1 step colder.


Jul 31, 2003
Thanks guys, but i gave up looking. I just ordered NGK TR7IX online with 2nd day shipping. was actually the cheapest online after shipping.


Founding Member
Sep 11, 2002
Visit site
The Autolite XP 103's are the factory plug for the Ford Lightnings. They are Iridium plugs, and probably arent kept on hand in a parts store. Im sure you could order them in for the next day.
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