We calculate the effect of rotation on resonance energies and widths of HCO using the adiabatic rotation method [J. M. Bowman, Chem. Phys. Lett. 217, 36 (1994)]. We test this approximate method against previous exact calculations for the even-parity resonances for total angular momentum J=1, and then apply the method for a range of J. We focus on the shifts in position and width of numerous resonances relative to nonrotating HCO for J=1, 6, and 20 and the body-fixed projection quantum number K=0 and 1. The variation of both resonance energies and widths it much greater for K=1 than K=0, and the implications for simple energy-shifting models are assessed. Some results are also presented for J=6, K=4 and 6 which illustrate the transformation of high-lying bound states for J=0 to resonances for J greater than zero. The implication of this transformation to theories of recombination is discussed.