Now, without trying to offend anyone, I believe that the wiring Diagram is incorrect, you wont get a pulse signal (which is required for a Tacho to work) from the + side of the coil. All tachos are wired on the negative side. Hence the White/Black wire. the tacho is wired in series on the 1200, if you wire it in parallel the car wont start, because that will just earth the points (effectively how a kill switch works) Hope this helps.