Guest Loose_Screws Posted April 18, 2005 Share Posted April 18, 2005 Has anyone connected their stock tachometer to MS? Since I bypassed the ENTIRE stock injection harness on my MSnS install, I have lost tach signal. Any thoughts on getting it working again? How about the water temperature gauge? Quote Link to comment Share on other sites More sharing options...
Tony D Posted April 18, 2005 Share Posted April 18, 2005 Everything hooks up same as stock. NO changes. Search out hte original wires, and go from there, hook 'em back up! Quote Link to comment Share on other sites More sharing options...
Guest Loose_Screws Posted April 18, 2005 Share Posted April 18, 2005 Everything hooks up same as stock. NO changes. Search out hte original wires, and go from there, hook 'em back up! Hook up the original tach to the tach input going to MSnS or to the FIDLE from MSnS? Thanks! Quote Link to comment Share on other sites More sharing options...
sims76 Posted April 18, 2005 Share Posted April 18, 2005 I think what Tony is saying is that the original tach wire (which should find it's way all the way up to the - of the coil) is not part of the injection harness and should still be there, assuming you didn't remove it also. Quote Link to comment Share on other sites More sharing options...
Tony D Posted April 19, 2005 Share Posted April 19, 2005 Sims is correct. The way the tachometer was ORIGINALLY connected in the Z will be UNCHANGED. If the car is a 240, the original tach wire went to the positive terminal on the coil, and if it's a 260, 280, or 280ZX, the wire goes on the negative terminal of the coil. It is totally separate from anything you did to the car, the coil connection is what determines the tach operation, and it remains unchanged after any of the installs/conversions. Quote Link to comment Share on other sites More sharing options...
Guest Loose_Screws Posted April 19, 2005 Share Posted April 19, 2005 None of the original wiring, coil, coil resistor, etc. is being used. In fact, most of that EFI system has been cut out. Locked down dizzy with VR connected to 4pin HEI which is providing tach to MSnS. FIDLE connecte to MSD 6A, which is connected to Fireball II. Any thoughts where to connect in the tach? Quote Link to comment Share on other sites More sharing options...
randy 77zt Posted April 19, 2005 Share Posted April 19, 2005 msd 6a has a tach output on the side of the box-use that.if you are using a 6a you cant get a good reading from - side of coil-because of multi fire at low rpm on msd. Quote Link to comment Share on other sites More sharing options...
Guest Loose_Screws Posted April 19, 2005 Share Posted April 19, 2005 msd 6a has a tach output on the side of the box-use that.if you are using a 6a you cant get a good reading from - side of coil-because of multi fire at low rpm on msd. Cool! I'll try that tomorrow (or whenever I can get away from work)! Quote Link to comment Share on other sites More sharing options...
Guest bastaad525 Posted April 19, 2005 Share Posted April 19, 2005 Tony D - you know, I should have asked you this directly a long time ago, you would probably know the answer to this... On my setup, '72 240 with a turbo motor, stock '82 EFI, running an MSD 6A ignition box, I was never able to figure out how to hook up the stock tach. I was under the impression from various things I'd read that it was not possible to get it to work in this setup... true or false? How would I get it working? Quote Link to comment Share on other sites More sharing options...
evildky Posted April 19, 2005 Share Posted April 19, 2005 I think the confusion is that the early tach's worked opposite later ones, can't remember which runs normal I went aftermarket a long time ago Quote Link to comment Share on other sites More sharing options...
Z Driver Posted April 19, 2005 Share Posted April 19, 2005 Tony D - you know' date=' I should have asked you this directly a long time ago, you would probably know the answer to this... On my setup, '72 240 with a turbo motor, stock '82 EFI, running an MSD 6A ignition box, I was never able to figure out how to hook up the stock tach. I was under the impression from various things I'd read that it was not possible to get it to work in this setup... true or false? How would I get it working?[/quote'] I was under the impression that MSD made a tach adaptor that was required to get the stock Datsun tach to work with it. It's PN 8910 I believe. Quote Link to comment Share on other sites More sharing options...
Tony D Posted April 19, 2005 Share Posted April 19, 2005 Bastaad, The 240 tach, when used with the original power transistor firing a ZX coil will hook up exactly the same as the 240, and will work. I had that question myself, and we decided "Lets hook it up and see what happens". So with the STOCK system, the connection of the 240 Tach to the "+" side of the coil will trigger the stock tach just fine. For an MSD, like Randy said above, the MSD's multiple spark system will draw more current that the stock system, so the stock Tach will not read right until about 4000rpms, when the MSD box goes back to a single-fire on the plug (they don't etell you it does that, but it does....) For that box to work, you have to use the "Tach" output wire, and either a 260/280 tach, or an aftermarket unit. I found the Autometer Silv-o-Lite gauge to be about $45 cheaper than a STOCK tach on my wifes' 260, so I used that! Wrapped it six or seven times with some electrical tape around the outer diameter, and stuffed it into the hole in the dash---everyone seems impressed.... LOL I'm not sure about any of the tach adapters they sell... Quote Link to comment Share on other sites More sharing options...
Tony D Posted April 19, 2005 Share Posted April 19, 2005 None of the original wiring' date=' coil, coil resistor, etc. is being used. In fact, most of that EFI system has been cut out. Locked down dizzy with VR connected to 4pin HEI which is providing tach to MSnS. FIDLE connecte to MSD 6A, which is connected to Fireball II. Any thoughts where to connect in the tach?[/quote'] Again, use the wires that originally hooked up to the coil. The EFI system is SEPARATE from the ignition system in these vehicles. Regardless of if the resistor is there or not, wether you are using the wires that connected to the resistor or not, wether the stock coil is there or not, unless you physically stripped those wires out of the main wiring harness (not the EFI harness, it's SEPARATE) with a razorblade, or totally rewired the front engine harness (not the EFI harness, it's SEPARATE) the wires ARE still there to be used. There is ONE wire that needs to hook up to the coil negative(-) terminal and it will drive the tach. If you are using an MSD, then that SAME wire needs to go to the MSD TACH output terminal on the MSD box. If you are really really really set on running another wire and duplicating something that is already there ready, willing, and able to do the job with only a SINGLE termination, knock yourself out. You need the not only hear what people are telling you, you need to listen to what is being said! What is being said is there is a simple wiring solution, the wire exists in a harness untouched by you thusfar, you just have to identify which wire it is and terminate it correctly, and your tach will begin working. Quote Link to comment Share on other sites More sharing options...
Guest Loose_Screws Posted April 19, 2005 Share Posted April 19, 2005 You need the not only hear what people are telling you, you need to listen[/i'] to what is being said! What is being said is there is a simple wiring solution, the wire exists in a harness untouched by you thusfar, you just have to identify which wire it is and terminate it correctly, and your tach will begin working. Tony D, I have no problem hearing or listening, I only wanted to ensure I was understanding correctly. I have no desire to create more work and if connecting the stock wire to the MSD output will work, I am all for it. I just want to avoid damaging my MSnS board. Let's keep this discussion friendly. Quote Link to comment Share on other sites More sharing options...
Tony D Posted April 20, 2005 Share Posted April 20, 2005 It's friendly, I just wanted to impress upon you that you twice said you altered the EFI harness, and wasn't sure you understood the wiring you needed to access was not in the EFI portion of the harness. The MS-n-S is totally isolated from this part of the circuit, you can hook it up without any problem. The only application that might have an issue, is the 240, due to that funky "+" setup on that tach... Quote Link to comment Share on other sites More sharing options...
Guest bastaad525 Posted April 20, 2005 Share Posted April 20, 2005 I do have one of the cheapest of the autometer tachs already... it is small like 3.5" or 4" I think and is currently sitting on top of my dash. So I'm covered but I just thought that... well I'd like to have the stock tach and nothing sitting on my dash... people see that and think I'm trying to be rice. I may at some point switch up to a larger tach that will fit in the stock location... that looks much nicer, but those tachs are expensive, hence why I skipped a bigger one the first time around. ah well, it was worth asking Quote Link to comment Share on other sites More sharing options...
Tony D Posted April 20, 2005 Share Posted April 20, 2005 just wrap more electrical tape around the outer diameter... Quote Link to comment Share on other sites More sharing options...
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