Energy-dependent metric for gravitation from clock-rate experiments

We carry out a detailed analysis of the data on the comparison of clock rat es between a flying dock and a clock at ground, performed by Alley and co-w orkers at the end of 1970's. The fit to such data is in favor of an energy- dependent metric for gravitation, whose time coefficient is at variance wit h the standard Einsteinian one in the weak-field approximation. By exploiti ng the formalism of a deformed Minkowski space-time, with metric coefficien ts dependent on the energy, we show that a possible lower limit on the prop agation speed of gravitational effects is about 10(10)c, in agreement with a recent analysis by Van Flandern based on the acceleration of binary syste ms.