This paper reviews previous work on spark assisted diesel engines and then goes on to discuss the results of investigations carried out at U.W. Results are given for two Army referee fuels and compared to D2 fuel results. The data concentrates on starting and low load running of Type I fuel which is a broadcut fuel with a cetane number of 20. Results are given for both two stroke and four stroke open chamber engines modified for spark ignition. The best results were obtained by directing one fuel spray at a raised central portion of the piston and spark igniting the resulting fuel cloud at a position 12 mm from the head and near the cylinder axis.