Abstract: The present invention discloses a monoblock engine in which the head and the block of the engine are cast integrally. The engine incorporates a cylinder and water coolant jackets, intake manifold and an exhaust manifold, vertical intake and exhaust valves, core removal holes, and a push-fit type cylinder liner which is secured in place so that leakage of fuel from the cylinder is eliminated. The water coolant jackets for the head and the block are connected using four water jacket gateways or connectors. The monoblock is fitted with the crankcase using a leak proof & robust flange-joint and mechanical fastening system which is easy to install. The invention is embodied for a single cylinder engine as well as multi-cylinder engines. By integrating cylinder head and manifolds with block, the critical joint between head and block and head and intake Manifold will be eliminated. At the same time, gasket and mechanical fasteners for tightening also can be eliminated.