As Zippy said, you have a wiring problem.

In NORMAL operation,

While running the ignition switch powers the run circuit which powers the coil through the ballast resistor.

While starting the ignition switch powers the start circuit, this bypasses the ballast resistor and powers the coil with full battery voltage to improve starting. You are not getting this voltage at the coil.

As a quicky confirmation, run a jumper wire from the battery + to the coil + and see if it starts.

The "bump" you are feeling happens when you release the key and the run circuit powers up letting the coil spark. It's not enough to actually start the car though.

Since this is an add on system the stock wiring diagram may or may not help.

The ballast resistor plays no part in the start circuit, any suggestions that this is the problem are given by those who do not know how the ignition system works, The closest it gets to being involved is being a place for the wires to connect. The fact that you are getting the "bump" as you call it tells us the ballast is ok.

I dug out my 67 FSM.

The STOCK wiring colors and what they do are as follows.

At the ballast

Dark Blue goes to the coil, this is the coil power lead in start and run
Brown hooks to the same side of the ballast as the Dark Blue wire above, this is where the voltage to power up the coil in START comes in ans is probably what is missing. This wire goes thru the bulk head connector ti the IGN2 terminal on the ignition switch.

On the other side of the ballast you have one wire, a Dark Blue one. This one provide voltage to the ballast in RUN, the power goes thru the ballast to the coil, again in RUN. The Other end of this wire goes to the IGN terminal on the mechanical voltage regulator.