Tachs for magnetos

[TMHEFFRON@aol.com]

I have a Vertex mag and I just bought an old (late 50's early 60's) SW tach at
a parts meet today, get home and read the instructions (in the box w/ original
literature) and it says it will not work on a Vertex magneto. I have a later
SW tach on the car now, but it is of a later period than the car and I'm
trying to make the car more correct. Does anyone know why the tach won't work
with a Vertex and maybe how I can make it work with the Vertex.

Thanks, Terry
58 Devin