How to Install Spark Plugs in a 1981 Corvette

The best spark plugs for a 1981 Corvette are the Delco platinum or iridium type. The platinum plugs advantage over standard plugs is its ability to resist fouling. The iridium plugs, though more expensive, have an additional advantage in their longevity; they also have the strongest electrode and can maintain their gap longer. The spark plug gap with the standard ignition coil is .040; however, an increased output from the coil or the addition of an MSD capacitor discharge ignition system requires a wider gap, as specified in the instructions that accompany the component.

Instructions

1

Remove all the new spark plugs from the box and install their accompanying metal washers. Always install the washer with the taper down. Gap the spark plugs according to specifications for the ignition system installed. If the system is stock, there is a placard on the radiator support shroud that details the recommended spark plug gap, timing and idle adjustment specifications.

2

Check all the spark plug wires for burn spots, cracking, missing insulation or torn spark plug boots. If any of the aforementioned is discovered, they should be replaced. The firing order on a Corvette is 1-8-4-3-6-5-7-2, and the distributor rotates clockwise. All the even-numbered cylinders are on the passenger side, while the odd-numbered ones are on the drivers side of the engine, starting with the lowest number cylinder located closest to the radiator. Always locate the Number 1 cylinder that is the closest to the radiator on the drivers side.

3

Follow the plug wire from the Number 1 cylinder to the distributor and mark the terminal with a piece of tape or marker. If all the wires are removed, start with the marked Number 1 cylinder and install the wires clockwise in the firing order mentioned in Step 2.

4

Twist the spark plug boot on the plug to be replaced to break it loose from the porcelain on the plug; pull the boot off. Make sure the engine is cold before removing the spark plugs. Remove the spark plug, using the ratchet with a short extension and socket. In the case of the front plugs partly hidden by accessory brackets, use the universal joint.

5

Loosen the plug by turning it counterclockwise. If the extension is difficult to turn by hand once the plug is loose, remove the extension and socket and use the -inch vacuum hose. Push the hose on the top of the plug and twist the hose to remove the plug.

6

Thread the spark plug in, by hand, to start with, so as to prevent any possibility of cross-threading the plug. If the plug is difficult to reach, use the vacuum hose again to thread the plug in. Tighten the spark plug until it is just slightly tighter than snug. Never over-tighten spark plugs, or they may break or stretch the cylinder head threads. The washers keep the plug from working loose once snugged down. Do the same for all the remaining spark plugs.