This study evaluated yarns produced on the DREF-3 friction spinning machine using varying core inlet sliver linear densities and output yarn core proportions. A long staple, medium micronaire, Acala cotton was spun into 74, 54, and 45-tex yarns at constant spinning drum and outlet speeds. Inlet sliver of 1.77, 2.47, and 3.18-ktex linear densities was supplied to the yarn core at rates required to produce yarns containing between 40 and 70 percent core. To make yarns of the same size and core ratio, lighter core sliver had to be supplied at faster inlet speeds or heavier core sliver at slower speeds. Using lighter core sliver at greater inlet speeds improved yarn strength and evenness. Among these, coarser yarns and those with higher core ratios showed better uniformity. Yarns supplied by lightweight core sliver showed similar elongation; those supplied by heavyweight core sliver showed more variation over the range of core ratios.