A wiring block and cover shell arrangement for electric connector in which the wiring block has two smoothly arched bearing walls perpendicularly extended from the front surface of the base thereof and equally spaced from the center of the base at two sides, two sets of parallel crevices symmetrically formed in the bearing walls and respectively cut through the height of the bearing walls to the base, and two sets of slots respectively cut through the height of the bearing walls and front and back sides of the base across the crevices for accommodating a respective wire clamp to fasten the insulated wires of the twisted pairs of a cable, maintaining an equal delay skew at each twisted pair of the cable.