Orbital studies of the cataclysmic variables CZ Orionis, V1193 Orionis and BZ Ursae Majoris

Time-resolved spectroscopy reveals the orbital periods of three cataclysmic variables. CZ Ori has an orbital period of 0.2189 d. This is within 3 per cent of a prediction relating orbital period and dwarf nova outburst decline time. We find the M2.5 ± 1.0 secondary, and infer an absolute magnitude for CZ Ori in |RKc| of 8.5 ± 1.0 and a distance of 260 ± 110 pc. V1193 Ori, also called Hamuy's Blue Variable, has an orbital period of 0.165 d. In 1988, Ha emission line profile variations suggested red star illumination. In 1989, this line's red wing flared at orbital phases 0.2 and 0.8. We set limits for the absolute magnitude in |RKc| of < 5.9 and for the distance of > 4 70 pc. BZ UMa has an orbital period of 0.0679 d, shown by Ha radial velocities and an S-wave. The velocities have anomalous low-frequency variations, strongest in the line wings. This rumbling, observed during all three observing runs, is of amplitude comparable to the orbit's. Explanations of instrumental effects, magnetism or disc waves are considered. The M5.5 ± 0.5 secondary implies an absolute magnitude for BZ UMain |RKc| of |$10.7 (+0.7/ -0.9)$| and a distance of |$110(+44/-51)pc$|⁠.