I have the NGK GR4 V power spark plugs in my car. Are the ZFR5N plugs so much better that I should change these?

The color of my plugs is rust orange, dose this mean anything? The engine runs fine so far.

thanks

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Grandpa's 1974 Dart Custom 4 door 225 auto, Aluminum Radiator, 1920 Holley.

There's nothing wrong with GR4s. You get a little better fuel economy and driveability with the ZFR5N plugs. Maybe next time you need plugs would be the time to make the swap. Remember to remove the metal ring washers from whatever plugs you install; they're not used on '63-'74 heads.

Rust-orange colour is due to whatever additives are in the fuel you're burning. As long as the plugs are otherwise clean, this shouldn't be a huge problem.

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Too many people who were born on third base actually believe they've hit a triple.

The plugs are new, so it will be awhile before the next change. The color is even across all cylinders and they are very clean. I live in upstate NY, who knows what they pt in the gas, 10% ethanol + whatever else.

I just removed the washers per your advise, that is when I checked the type and color. Thanks for all the great info.

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Grandpa's 1974 Dart Custom 4 door 225 auto, Aluminum Radiator, 1920 Holley.