Spark Plug Heat ranges

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Apr 16, 2015 | 07:40 AM

rustyrudder

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Spark Plug Heat ranges

Hey yall, quick question.

After much conversation, mostly with myself, I have decided to try to find a "colder" spark plug for my truck. I understand that every spark plug has a different heat range rating, but I'm not sure how to compare spark plugs from different manufacterers, or if this can even be done. Is it apples to oranges?

Also, where do you buy the different plugs? Autozone, advanced, all of those stores pretty much just have one kind of each brand. And to make matters even worse, I have an EFI head which has a longer electrode than most other spark plugs. Do I have to special order a colder plug?

Thanks!!

Apr 16, 2015 | 08:48 AM

The Frenchtown Flyer

Fleet Mechanic

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Why do you want to switch to a colder plug? What do you expect to gain? Have you upped the compression ratio by several numbers?

Modern spark plug designs are more compliant over a broader range of temps than older versions. Unless you are using a turbo or increasing the compression ratio to race-only levels I see no need.

Apr 16, 2015 | 08:57 AM

Harte3

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From: Spokane, WA

"I have decided to try to find a "colder" spark plug for my truck."

For what purpose?

Apr 16, 2015 | 08:36 PM

ZarK-eh

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Joined: Sep 2014

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From: like subarctic, brrr man!

I would check the plug colours to be sure. EFI engines should run a bit hotter than carb ones for emission reasons, as the EFI computer expects it.

That said, I use Autolite APP1525 Double Platinum and Gapped them to .060" (Stock is .044") as I'm running a custom computer and a wasted spark coil pack for big dwell times. I expect to get decent life out of them and just pulled one and they are a nice tan colour.

Apr 28, 2015 | 10:07 AM

rustyrudder

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I apologize for the late reply, basically I was getting a sort of a white glaze to the insulator and I was under the impression this could be from an incorrect plug heat range. My compression ratio isn't anything to write home about, and I realize this glaze could be a result of running too lean, or having my ignition too advanced. I don't hear any pinging, so I figured to move onto the next step which was plugs. Am I off base here? I've been checking the plugs regularly, and they are consistent. Also, my gas mileage has been pretty good, 15-16 mpg on the highway.