Also I suggest try run without the tachometer.
I found that sometimes the engine will not run right.
and some times will not start at all.
Look to see if the tach is a v2 or v3.
if is v3 chances are that could have interface .
rcxel changed the hardware and ch do not work well with v3.
I am working on a new Timing board that will not be influenced by the tach.
Adrian