What does the abbreviation BTDC stand for?

Answer 1

Before top dead center. Used in auto ignition repair processes of timing the firing of the spark plug to the preferred position of the cyclinders on the compression stroke.

Answer 2

BTDC stands for "Before Top Dead Center," which refers to the position of a piston in a combustion engine relative to the top of its stroke, usually measured in degrees of crankshaft rotation. This term is commonly used when discussing ignition timing in engines.