1-Be sure to keep the drill at a 90-degree angle to the surface when drilling.
2-Cut threads in the hole with the tap provided, and be sure to lubricate the tap with cutting oil.
3-Ensure that the tap is properly aligned and perpendicular to the workpiece to prevent cross-threading.
4-Clamp the appropriate tap in a tap wrench.
5-Commence the thread cutting using firm and even pressure - with a quarter turn clockwise, followed by a quarter turn anti-clockwise to clear the metal shavings from the thread.
Attention: This product is not suitable for spark plug thread repair!!!