Guest James 72 240Z Posted July 27, 2001 Share Posted July 27, 2001 (L24 in a 72 240z) 79-81zx distributor and MSD Digital ignition (MSD-6520). If so, I'd like to discuss installation war stories (my battle continues) especially with respect to getting the tach to work (and yes, I have the tach adaptor). Quote Link to comment Share on other sites More sharing options...
spotfitz Posted July 28, 2001 Share Posted July 28, 2001 Have you gotten the tach to work at all? If it is working, but jumping around, especially with an electrical circuit drawing current, (like a turn signal) then it is power draw. The MSD draws alot of juice considering what our original alternators produce. I don't have the dist. you discribe, but have noticed some funny things going on with the tach during high draws on the battery. I plan to upgrade the alternator to relieve this issue. Bad electrical connections could also be a problem. Hope it helps Quote Link to comment Share on other sites More sharing options...
Guest Anonymous Posted July 28, 2001 Share Posted July 28, 2001 i also had a digital 6 with an 82-83 zx dist.the autometer looks great in the stock location.early z car tachs are just like boat motor tachs ask for an msd marine tach adaptor.some marine supply places carry them. i found this out after i put in the aftermarket tach. Quote Link to comment Share on other sites More sharing options...
deMideon Posted March 26, 2002 Share Posted March 26, 2002 Boat motor tach adapter? Does MSD make it? Is that all you need? You wouldn't happen to have the part number would ya? I've been driveing around for quite a while without a tach in my 73 240 and haven't been able to find out what would really work. Thanks!! Quote Link to comment Share on other sites More sharing options...
deMideon Posted April 4, 2002 Share Posted April 4, 2002 Here's a post from 240Z.org e-mail list, it's not the digital MSD but it may work the same way! After missing a functional tach after my MSD 6A install, I found a post on utilizing a modified 280z tach. I didn't swap the face (kept 280z tach face), I simply performed the following steps: Remove 280z tach from tach housing (280z units are attached to dash differently). While you have the 280z unit exposed, find the medium sized resistor under the tach signal/input feed and jump it w/a small wire using a solder gun (believe resistor was brown w/some stripes...but don't quote me). Install 280z unit into 240z housing. I am sorry for not documenting this more clearly, the resister was pretty easy to identify once I opened up the 280 unit. You could test your newly modified tach before completing the dash installation by wiring it up under the hood (near the ignition coil). The modified 280z Tach will now get it's input signal directly from the TACH output on the MSD box. After you verified that everything works, simply return the tach to the original dash location and you are smiling again. Don't grin too hard, manny 72DD Quote Link to comment Share on other sites More sharing options...
Guest James 72 240Z Posted April 8, 2002 Share Posted April 8, 2002 Yes, I do now have a functioning 72 tach with the digital ignition box! If I remember correctly I closed the ballast resistor connectors and then plugged the +ive from the tach adaptor into the tach connector. Apparently the 72 tach feeds off of a +ive signal and won't work using the -ive. When I visit my car later this week (I don't store it at home) I'll make a detailed schematic and post it. Works like a charm though. Quote Link to comment Share on other sites More sharing options...
deMideon Posted April 9, 2002 Share Posted April 9, 2002 I will be finishing a 240Z very soon that I have sold. So I think the guy I am selling it to would love to have a working tach. Thank you! Quote Link to comment Share on other sites More sharing options...
Guest James 72 240Z Posted April 10, 2002 Share Posted April 10, 2002 OK, here's how I did it: You need the MSD tach adaptor #8920 to do this. I am using an MSD coil too so I bypassed the ballast resistor and connected the ballast wires together. On my car they are a black/white wire and a green/white wire. There is another black/white wire coming in from my harness but it is taped up with a solid black wire so be careful as to which black/white wire you connect to the green/white wire. The solid black wire that is paired with the other black/white wire routes back to my tach. Connect this solid black wire, or whatever wire runs back to your tach, to the positive wire from the tach adaptor (mine is red). I believe this is where most of the confusion lies in that the instructions indicate to connect the purple wire to the tach wire. I did this initially and my tach worked but it displayed the rpms at approximately 2.5 times the actual motor rpms. And finally, connect the tach output wire from the tach adaptor (mine is white) to the tach output on your MSD box. That should do it. If anyone else has done this and I have left anything out or mixed something up please let me know. Quote Link to comment Share on other sites More sharing options...
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