An experimental investigation was carried out to find out the effect of injection timing on performance and emissions of a single cylinder, 4 stroke, and compression ignition engine at various cooling rates. Original injection period of the engine was 240 CA and injection starts at 140 CA BTDC, injection timings were reduced to 220 and 200 CA by delaying the starting of injection at 120 and 100 CA BTDC. Several experimental cycles were conducted at various loads i.e., at 0.5, 1, 1.5, 2, 2.5, 3KW load at cooling rates of 3, 4, 6 lpm of engine water cooling rate. Emissions such as NOx, CO, CO2, UHC and unreacted oxygen was measured by using multi gas exhaust analyzer.