> e had a pulse indicator that went inline with the injector line,  but
> I had a friend, who claims he installed a pickup on the valve cover
> pointing down towards a rocker arm.  Each time the rocker arm went down
> it would send a pulse.  He would then multiply and divide to get rpm.
> He had the same problem finding a place to access a rotating shaft, and his
> valve cover was cast alum.  which made it easy to dill and tap.
>
> This is a wild way, but it does provide a solution.
>
I've seen a tach for model car/plane engines the uses a sensor glued to
the back of the
crankcase (aluminum) and picks up the crankshaft rod pin (steel) through
the case.