How to Switch Spark Gaps

Switching or changing the spark plug gap on your vehicle becomes necessary when readjusting the gap due to normal plug wear or when installing new spark plugs. The tip of the spark plug contains an L-shaped electrode that sits over a firing tip. The gap between the electrode and firing tip must sit within a prescribed distance in order for the spark plug to deliver the correct strength and heat of the ignition spark. The wider the gap, the cooler and weaker the spark. If the gap is too short, the spark may be too fast and hot for proper ignition

Instructions

1

Set the vehicle in park or neutral with the emergency brake applied. Raise the hood and disconnect the negative battery cable with a socket and wrench. Use a pair of insulated spark plug wire pliers to remove the plug wire from one spark plug. Grip the plug wire at the boot and pull it off. Use a plug socket and wrench to loosen and remove the spark plug in a counterclockwise direction.

2

Inspect the spark plug number for its correct size and rating, according to your owner repair manual's specifications. Remember the number when removing all other spark plugs. If reinstalling the old plug, use a wire brush and carburetor cleaner to clean the electrode portion. Wipe it dry with a rag. If the plug appears black, wet with fuel or has a heavy white encrustation, replace it with a new one.

3

Refer to your owner's repair manual for the correct spark plug gap for your engine. You might find this specification on a placard or sticker on your fan cowl or engine compartment frame. The correct number will be listed in thousandths of a inch, like .035 or .032. Slip a feeler gauge that has that corresponding blade number between the firing tip and electrode. If the gap is too wide, gently tap the electrode on a hard surface to narrow the gap.

4

Use a plug gap tool that has graduated wires on a gauge, if you prefer this type. Stick the correct wire thickness between the firing tip and electrode. Open the gap with the other end of the tool that has the pry function. For the graduated scale plug gap tool, narrow the gap by tapping, then insert the beveled slider into the gap and force the gap open.

5

Clean and gap all spark plugs with this procedure, but do them one at a time so you do not mix up the spark plug wiring order. Use the spark plug socket and wrench to screw the plugs back into the head, but do so only with a snug fit. Refer to your owner's repair manual for the correct foot-pounds in torque required for your plugs. Set a torque wrench to the correct foot-pound number and tighten them with the torque wrench.

6

Reconnect the negative battery cable with a socket and wrench. Start the engine and check for smooth engine operation and tight plug wire fits.