--- by Aaron Turpen on 20-Mar-2015
When changing the timing belt/chain or adjusting timing on a vehicle, understanding the timing marks on the crankshaft and camshaft pulleys is key to getting it right. Tuners will also need to be intimately aware of these marks as they are integral to tuning RPM rates.

Most engines will have two or three marks on the inner crankshaft pulley to be lined up with the “arrow” mark on the engine block. Similar marks will usually be found on at least one of the camshaft pulleys. When the timing belt or chain is properly installed, the mark set to the block mark on the crankshaft will be identical to the mark set to the camshaft and head. The goal of setting timing is to have this lineup happen.

The top dead center (TDC) mark can be the center, left, or right mark, depending on the engine. On the majority of engines, it is the center of three marks, but your specific vehicle may differ, so reference your owner’s manual and/or shop repair manuals.