I have a 72 Chevelle with a 402 that always had a little low rpm hesitation. I had motor professionally rebuilt and hesitation is still there but a lot worse. I have installed new rotor, points, cap, plug wires,coil, plugs, fuel pump, carb. rebuilt,dwell and timimg are right on. Hesitation seems to be worse after warming up.

Hesitation problems like this can be a bear. Give me a little info on the distributor. Is it the original points distributor? If so, here's what I want you to do. Remove the cap and try to turn the rotor in its normal direction of rotation. It should turn just a bit, maybe about 15 to 20 degrees, and snap back when you let go of it. If not, the mechanical advance is seized and the distributor will need to come out so it can be disasembled and cleaned up. Next, obtain a hand held vacuum pump and disconnect the vacuum hose from the cannister on the side of the distributor. Connect the hand held pump to the cannister, pump it up, and see if the base plate the points are mounted on moves. If not, either the vacuum cannister is bad, or again, the mechanism is frozen and the distributor will need to be removed for a good cleanup. Timing advance is very important and if it doesn't advance properly, you will have hesitation problems.

If all of this checks out, we'll address the carb next.

Hi and thank you for your help.
The points distributor is the original and I have tryed turning it in its normal direction and it snaps back OK.
I have not tryed A pump on the cannister to see if the base plate moves.
I will try this and get back to you
THANK YOU