I'm building a fuel only system and would like to build/install a tach filter.
Tried both Howell & AFI, neither are willing to sell me one.

Plan is to use an MSD 6A box, but would like to use a tach filter.

Been searching, found some references, but no schematic.
Anybody out there have something I could use to build a tach filter?

It has to be a fuel only system, in order to get it through smog in CA.