H or D atom velocities are reported for dissociation from several vibrational levels in the lowest 2500 cm(-1) of the (A) over tilde (2)A" state of two vinyl radical isotopomers, C2H3 and CD2CH. Energies are inferred for the acetylene product and compared with both theoretical and experimental work. An upper bound is given for the rate of H-atom scrambling between the alpha and beta carbon atoms. (C) 2003 American Institute of Physics.