The engines are tilted approx 15 degrees to left (exhaust side) to make room for the more complicated injection systems. B19 and B21 blocks can be identified by water plugs on one side of the block. The B23 blocks have them on both sides. The camshaft is driven by a toothed belt that is driven off the front of the crankshaft. The belt turns the intermediate shaft as well, which in turn drives the oil pump, distributor (on 240 engines and BXX 700/900 series engines) and the fuel pump of carburetor models. All single camshaft versions of the engine with the exception of the K series (B200K, B230K) are of 'non-interference' design, meaning that failure of the toothed belt will not result in engine damage.