Monte Carlo (MC) simulations have been performed for propane and four fluoro propanes : HFC-245ca, HFC-245cb, HFC-236fa and C3F8, using a transferable potential model which agrees well with quantum chemical calculations. Although the MC results on the thermodynamic properties show qualitative agreements with the experimental data, the quantitative agreements are not satisfactory. A scaling factor is therefore introduced empirically into the potential function to improve the agreements of the MC results with the experiments. Using the scaling factor, it is found that the agreements are clearly improved. The carbon-carbon pair distribution functions obtained from the MC simulations are compared with the experimental x-ray scattering data of propane. The agreements between the simulations and the experiments are good.