In this paper investigations performed on dual fueled constant speed diesel engine. At first; performance and emission of diesel engine investigated and after converting to dual fuel mode experimental tests performed on performance and emissions in different injection timing (at 14, 17, 20 degree before TDC) and loads (100%, 75%, 50%, 25%, 10% of full loads). Results show that in different loads and injections timing, amount of Nox and particle materials (PM) in dual fueled engine are lower than diesel engine. Amount of CO2 in dual fuelled mode have a little difference with diesel mode, although, it is lower than diesel engine. In loads lower than 75% load, amount of CO in diesel engine was lower than dual fuelled engine but in full load this term was inverse and have significant difference. Amount of HC in dual fuel mode was higher than diesel mode in all injections timing and loads.