Answer for What is T.D.C. and B.D.C.
The extreme top position up to which a piston reaches in its stroke cylinder, is known as “Top Dead Centre”(T.D.C.). This position is indicated by a mark on the fly-wheel. All adjustments for engine efficiency are made with relation to this position as a basis.
B.D.C. : The term B.D.C. stands for “Bottom Dead Centre”. The extreme bottom position upto which a piston goes in its stroke in the cylinder, is called B.D.C.