Bahraini240z Posted July 31, 2011 Share Posted July 31, 2011 After installing the MSD ignition the tachometer does not work. I bought the MSD RPM convertor and still can't get it to work. Running an L28 with triple Mikuni 40PHH carbs Quote Link to comment Share on other sites More sharing options...
beermanpete Posted August 1, 2011 Share Posted August 1, 2011 The '73 has a 4-wire tach that uses the current pulse to trigger it, no the voltage pulse from the points. The MSD ignition might not have the correct current pulse shape to properly trigger the 4-wire tach. The easiest soution is an aftermarket tach or perhaps a 3-wire tach from a later model Z. I have seen adapters available for this situation. Search on the internet for information related to Smith tachs used in the early English cars. They are also current sensing types. Quote Link to comment Share on other sites More sharing options...
johnbell Posted August 1, 2011 Share Posted August 1, 2011 I gutted my tach case and put the workings of a Sun super tach in. Works good! the only real challenge was the needle, I had to ream the Datsun needle with a tiny little drill bit to get to the correct size..but it looks stock. Quote Link to comment Share on other sites More sharing options...
Bahraini240z Posted August 1, 2011 Author Share Posted August 1, 2011 Wow! Never thought it would never work! I wanted the all oem gauges functioning to maintain originality Quote Link to comment Share on other sites More sharing options...
coolhand Posted August 3, 2011 Share Posted August 3, 2011 There are 2 different tach adapters. You may have gotten the wrong one. I ran MSD on my 73 for years and never had a problem. I would make sure you have the correct adapter and recheck all wiring. The part # for the correct one is 121-8910. This adaptor is for points or amplifer. Your ride came with a points dizzy. The other adapter is for a dizzy with a magnetic pickup. Quote Link to comment Share on other sites More sharing options...
Bahraini240z Posted August 4, 2011 Author Share Posted August 4, 2011 I got the MSD 8920 according to this thread: http://forums.hybridz.org/index.php/topic/37376-getting-your-early-240z-tachometer-working-with-an-msd-6-series-ignition/page__p__298874__hl__%2Bsearch...msd+%2B8920__fromsearch__1#entry298874 Quote Link to comment Share on other sites More sharing options...
Nigel Posted August 4, 2011 Share Posted August 4, 2011 (edited) The 8920 looks like the correct adapter for a current driven tach. When you say MSD ignition, are you talking about the 6AL? I think a lot of the problems that people have with this installation comes from how they wired the MSD 6AL. To start, what exactly did you connect the Red and White wires on the 6AL to? Also, what did you do with the original ballast resistor? Nigel '73 240ZT Edited August 4, 2011 by Nigel Quote Link to comment Share on other sites More sharing options...
Bahraini240z Posted August 4, 2011 Author Share Posted August 4, 2011 Yep, referring to the 6AL Not sure tho what my mechanic do, he just told that he tried many things and wasn't able to get it work. Trying to find the correct way so I can inform him Quote Link to comment Share on other sites More sharing options...
Nigel Posted August 4, 2011 Share Posted August 4, 2011 Yep, referring to the 6AL Not sure tho what my mechanic do, he just told that he tried many things and wasn't able to get it work. Trying to find the correct way so I can inform him It's going to be tough to troubleshoot without knowing exactly what was done. I've never installed a 6AL or tach adapter personally, but I am a career electrical designer, and I can tell you what I'd do if it were me hooking all of this up. But first, do you at least know what was done with the distributor... Original distributor with original points Original distributor with Pertronix ignition Original distributor with Optical Pickup like a Crane ignition 280Z/ZX distributor Nigel Quote Link to comment Share on other sites More sharing options...
Bahraini240z Posted August 4, 2011 Author Share Posted August 4, 2011 280zx distributer with MSD 6AL Quote Link to comment Share on other sites More sharing options...
Nigel Posted August 5, 2011 Share Posted August 5, 2011 (edited) The formatting got screwed up when I posted. I hope this fixed it... The first thing to do is to identify 3 of the original ignition wires. Black/White Wire originally connected to the coil (+) terminal (0VDC with ignition switch at ON. +12VDC with ignition switch at Start) Green/White Wire originally connected to the Ballast Resistor Black/White Wire originally connected to the Ballast Resistor. (+12VDC with ignition switch at ON and Start) Even though there are two Black/White wires, they are not part of the same piece of wire, and they must be correctly identified. To do this, with all three wire disconnected, turn the ignition switch to the ON (Run) position and measure the voltage to ground at each of the Black/White wires. One of them should have +12VDC, and the other should not. The one without +12VDC is the original coil (+) wire. Once that's been sorted, connect the Green/White and Black/White wires that were originally connected to the Ballast Resistor to each other. This is going to be your Ignition ON source for the MSD 6AL and the 280ZX distributor. Now you can connect everything as outlined below: MSD 6AL Heavy Red Wire to (+) Battery terminal Heavy Black Wire to (-) Battery Terminal Red Wire to (+)12V Ignition ON (to original Ballast Resistor Black/White and Green/White Wires which are now connected together) White Wire to 280ZX Distributor "C" (Top of T) Terminal Orange Wire to Coil Positive Black Wire to Coil Negative Magnetic Pickup (Violet and Green wires) - Not Used Tach Output to MSD 8920 White Wire 280ZX Distributor C (Top of T) to MSD 6AL White Wire B (Leg of T) to (+)12V Ignition ON (to original Ballast Resistor Black/White and Green/White Wires which are now connected together) MSD 8920 Red Wire to Original Black/White Coil (+) Wire White WIre to MSD 6AL Tach Output Black Wire to Chassis GroundViolet Wire - Not Connected You may need to install a diode in series with the Black/White wire connected to the Alternator External Voltage Regulator to prevent engine run-on after the key is switched off. Nigel Edited August 5, 2011 by Nigel Quote Link to comment Share on other sites More sharing options...
Bahraini240z Posted August 5, 2011 Author Share Posted August 5, 2011 Thanks for the great write up.. Will check that and let u know how it goes on Thanks again Quote Link to comment Share on other sites More sharing options...
chuckles Posted August 28, 2012 Share Posted August 28, 2012 Hey nigel, did you ever have any issues with the tach on this after you removed the resistor from the tach circuit? Quote Link to comment Share on other sites More sharing options...
Conedodger Posted September 25, 2012 Share Posted September 25, 2012 I'm having the same problem. No tach but on a 1973 240Z MSD6AL - original single point distributor - MSD 8910 tach adapter Power wires are connected directly to the battery Red to black/white stripe wire White to distributor Black to Coil negative post Orange to Coil positive post Quote Link to comment Share on other sites More sharing options...
Nigel Posted September 25, 2012 Share Posted September 25, 2012 The 73 Z has a current driven tach. Try the 8920 adapter instead. Quote Link to comment Share on other sites More sharing options...
Conedodger Posted September 25, 2012 Share Posted September 25, 2012 The 73 Z has a current driven tach. Try the 8920 adapter instead. Thanks! Quote Link to comment Share on other sites More sharing options...
chuckles Posted September 26, 2012 Share Posted September 26, 2012 Yep the 8920 is what works. Quote Link to comment Share on other sites More sharing options...
Nigel Posted September 26, 2012 Share Posted September 26, 2012 Yep the 8920 is what works. Thanks for the confirmation. Sorry I never answered your question from a few weeks back, but I've never actually installed one of these. I'm just going by theory. So, I didn't really have anything to tell you. Nigel Quote Link to comment Share on other sites More sharing options...
chuckles Posted September 26, 2012 Share Posted September 26, 2012 Just so you know your instructions work fine. Thanks.. Quote Link to comment Share on other sites More sharing options...
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