The valence state dependence of the Ar-HF interaction potential is extended to upsilon(HF)=4. Three new ArHF (upsilon(HF)=4) states, (4000), (4100), and (4110), are observed between 14 780 and 14 880 cm(-1) using intracavity laser induced fluorescence. The term values and rotational constants of these states are the following: (4000) nu(0)=14 783.603 23(30) cm(-1), B=0.103 606 8(68) cm(-1); (4100) nu(0)=14 867.419 06(70) cm(-1), B=0.102 612(27) cm(-1); and (4110) nu(0)=14 875.048 30(39) cm(-1), B=0.103 217(19) cm(-1), respectively. The spectral red shifts of ArHF (upsilon 000) dramatically increase from 9.654 cm(-1) at upsilon=1 to 48.024 cm(-1) at upsilon=4. The rotational constant of ArHF(4000) increases essentially linearly with HF valence excitation, becoming 1.3% (40 MHz) greater than that observed at upsilon=0. At upsilon=4, the outer classical turning point of HF is extended by 0.4 Angstrom from r(e), and there is no evidence for Ar-H repulsion. The spectral red shift for linear hydrogen bonded Ar-HF(upsilon 000) indicates a strong enhancement of binding energy upon HF valence bond excitation, while the rotational constant reveals an almost surprising decrease in heavy atom separation. Both the T-shaped ArHF(upsilon 110) and antilinear Ar-FH(upsilon 100), however, show very little dependence of binding energy upon upsilon(HF) valence excitation. These observations are in good accord with the ab initio intermolecular potential surface.