Can a Pertronix unit "begin to fail" or "partially fail" and the engine still run some? The rpoblem I am having is that the motor will run OK till around 4000rpms and then gets realy sick and sound s much like bad points or a weak coil. I wasn't sure if these units were either on or off or if they could partially fail. Any ideas? This is a weber 'd car btw so injection isn't an issue...//Peter

sounds like a fuel starving issue instead....

pertronix fails usually completly...

you have beans and all of a sudden you don't

and then your like cause thats 65 clams you spent that just died.

Check for interference between the rotor and P-unit. If you have changed rotors, some are slightly larger in diameter and will rub the unit, create a dust and cause poor running.

This is even more true if the dizzy shaft is wobbly (worn out).

Measure fuel pressure to carbs...

Check float levels too....

Maybe, the fuel pump is not able to supply necessary volume at higher rpms. Maybe the float level is to low, starving the jets at elevated rpms
Maybe, the jets are fouled (insufficient fuel flow)

What condition is you dizzy cap, rotor and high tension wires?