Spark Plug Pull & Check
Applicable Years: C1, C2, C3, C4, C5, C6
Skill Level: 1 Wrench
Tools Required: Spark plug socket, ratchet, plug boot pliers
Time Required: 1 hour
Parts Source: Favorite Corvette parts/accessory supplier, local auto parts store, or auto department of a mass merchandiser
A spark plug is one of those parts that most folks scarcely give any thought to . . . until their engine starts missing, running rough, or develops some unhealthy symptoms. That's why it's a good idea to pull and check your spark plugs at regular intervals-for example, with every third oil change. Checking your plugs is not hard to do, although it's a tad more difficult on some Corvettes than on others due to plug location, exhaust headers, and/or other obstacles that may make them hard to reach and remove.
Start by pulling the plug wire off at the boot (investing in a pair of plug boot pliers is a good idea to avoid damaging the wires or the boots as they're made specifically for this purpose). After the plug wire is off, use the ratchet and socket to remove the plug and inspect it. Check the plug to make sure the electrode isn't burned away, that there's no cracking of the ceramic body, and that the color of the center electrode looks good (optimally, the electrode should be a tan color). Black indicates the engine is running too rich, thus producing a lot of carbon resulting from fuel that isn't burning properly, and a whitish color denotes the engine is running too lean. If the plug indicates you're running either rich or lean, some adjustments should be made to correct the situation and a full tune-up wouldn't be a bad idea.
If everything looks fine, just replace the plugs and push the plug wire boots on all the way. While the plugs are out of the engine, it's a good time to replace them with new ones, perhaps an upgraded plug such as the ones from E3 that don't require any gapping. If you're replacing your plugs with conventional ones, be sure to gap them correctly according to the specs in your Corvette service manual.