Recommendations for a filter to get the tach working.

[MAC71Cheyenne]

Yes, no, not needed, needed, ??? Older posts and searches are like a blindfolded drunk driver.
71 C10 wV8. New Summit HEI dist and ignition box. Tach doesn't work properly, runs negative..or positive but never hits 1000 rpm. Disconnected the wire to the cap, (no inline GM filter) so it does not burn up. Obviously I would like to have the dang thing functioning properly.
Thoughts and recommendations....