'68 Jaguar E-Type 2+2 4.2L 6 with a Mallory Hyfire 690 box connected to a Mallory 27 series distributor fitted with a Unilite #560 breakerless conversion. Everything works great, but I'm unable to get a tach reading at my tachometer (yes, I followed the proper wiring). I contacted Mallory who suggested I fit a tach adaptor (8920), it still doesn't work. For the in-dash tach, I'm sending it out for a conversion to work directly with the Mallory control box. What is really odd, I cannot get a tach reading when connecting my tach/VOM directly to the '-' side of the coil. Am I doing something wrong?