FastWoman

Any thoughts as to whether one of these could be used (probably with modified output)??? http://rt-eng.com/mediawiki/index.php/RTE_67-74_Tach_kit The firing frequency for a 6 cyl at 8000 RPM would be the same as that for an 8 cyl at 6000 RPM (the upper end of the scale these tach boards are designed for). The board is actually supposed to handle higher RPMs too.

Thanks, guys! Mark, I've emailed EScanlon to see if he found any solutions. Thanks for the referral. Yes, my tach is a negative wire hookup. According to my service manual, it has a +12 supply, gnd, and the signal off of the coil ground. I presume the noise picked up off of the coil ground triggers one-shot pulses. Yes, the 240Z tach does seem to be a completely different beast. Steve, I think you probably gave me the info I needed. I'm surprised the circuit used a custom IC. Nevertheless, the tach movement would be a galvanometer just like any other galvanometer (right??), and it should be possible to construct a replacement circuit board to drive the thing (should it not?). Hopefully I'll hear back from EScanlon pretty soon with those answers. How often do these things go bad? In your opinion, would there be any market for a replacement PC board? Perhaps I'm just cheap, but it seems excessive to throw a few hundred dollars at a junkyard part that might also soon fail. The most common failure mode would seem to be the board, which by some reports seems to go funky with higher system voltages. (My system charges at 15.1V. That seems awfully high, but I remember my old '75 car also having a 14.5-15V spec range.) Thanks for your help! Peace, Sarah

That happened to my old '75 back in the mid '80's. It was a rusted fuel siphon tube in the gas tank. When it got to 1/2 empty, the fuel pump was sucking air through the rust hole.

Hi all, I'm new to the forum. I just bought a nice little '78 280Z. It's wonderful to own an S30 again. Back in my younger days I owned a '75, and it was the best car I ever owned. My ex made me sell it. :ogre: It's been 15 years, but I'm back behind the wheel of one of these beautiful machines. Like another recent poster, I have an erratic tach. It doesn't go completely wonky, pegging both ends of the scales and such. Rather, it seems to read about half the correct RPMs, sometimes drifting up and down a bit -- sort of wandering around. Aside from that, the tach seems to be in nice condition. The electronics geek in me recognizes that I don't have to spend hundreds for a new/used/reconditioned replacement tach. The meter movement is basically sound, so all that should be required is repairing/rebuilding the circuit board. It's probably some Schmidt trigger design -- something with a one-shot circuit. Basic stuff. My question is this: With so many of these tachs failing, has anyone shared a schematic of the circuit with their fellow Z owners on the Internet? Helpful links? Or perhaps someone makes a replacement PC board? Any leads would be greatly appreciated. On another matter, does anyone know where I could find a new fusible link block? One of mine has a broken mount. Thanks! Peace, Sarah