Factory Tach Hookup |
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EAlonso761
New Member Joined: 08-April-2019 Location: California Status: Offline Points: 2 |
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Posted: 09-April-2019 at 1:03PM |
Need wiring diagram for factory tach 1972 Ranchero. I have Fast Fuel Injection and E6 CD Ignition with E-92 coil. The factory tach usually would hook up to the positive side of coil.
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EAlonso761
New Member Joined: 08-April-2019 Location: California Status: Offline Points: 2 |
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Need help wiring with CD Ignition and Fuel Injection
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californiajohnny
Moderator Group Joined: 05-October-2013 Location: winlock, wa Status: Offline Points: 14606 |
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JOHN
74 GRAN TORINO S&H CLONE 74 VETTE CUSTOM 90 S10 BLAZER 4X4 LIFTED 77 CELICA CUSTOM 75 V8 MONZA SUPERCHARGED 79 COURIER VERT. SLAMMED 75 VEGA V6 5 SPD 70 CHEV C10 P/U 68 MUSTANG FB CONVERSION |
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californiajohnny
Moderator Group Joined: 05-October-2013 Location: winlock, wa Status: Offline Points: 14606 |
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that's the factory tach wiring now if youre using an MSD box or something like it, you may need to wire it differently... there is some discussion about that on here somewhere....
i know todd and scott posted about that somewhere, search "tach no worky worky"??? |
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JOHN
74 GRAN TORINO S&H CLONE 74 VETTE CUSTOM 90 S10 BLAZER 4X4 LIFTED 77 CELICA CUSTOM 75 V8 MONZA SUPERCHARGED 79 COURIER VERT. SLAMMED 75 VEGA V6 5 SPD 70 CHEV C10 P/U 68 MUSTANG FB CONVERSION |
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Rockatansky
Senior Member Joined: 30-July-2010 Location: On The Road Status: Offline Points: 6059 |
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IIRC 1972 uses the 2 wire system that powers the coil through the tach in series, not just hooked up to and taking siganl from the coil. the later 3 wire tach is the one you want, same wiring as aftermarket reading coil signal |
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72 GT Ute
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72FordGTS
Admin Group GTS.org Admin Joined: 06-September-2005 Location: Ontario, Canada Status: Offline Points: 5802 |
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Like the wiring diagram shows and the other guys mention, the 1972 Tachs are current sensing. They get the reduced voltage after the resistor wire, which means they were never desiged to even handle a full 12 volts. Pretty much any aftermarket ignition is going to want a full 12 volts, not the 8 volts the resistor wire will give and the Tach requires. Some CD igntions, like MSD, offer kits to make a current sensing tach work, but I have heard mixed results.
So long story short, you best and easiest solution is to send the Tach to Rocket Man and have it converted to a voltage sensing tach that will read from the negative side of the coil. That way you can run it with any ignition without worries. Edited by 72FordGTS - 10-April-2019 at 1:07PM |
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Vince
1972 Ford GTS Sportsroof - Survivor, One Family car GTS.org Admin |
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Rockatansky
Senior Member Joined: 30-July-2010 Location: On The Road Status: Offline Points: 6059 |
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looks like the factory 3 wire tach started mid 1976? you could just swap it out if you don't mind the font mismatch or get gauge overlays i wonder if the faces can be swapped? |
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72 GT Ute
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72FordGTS
Admin Group GTS.org Admin Joined: 06-September-2005 Location: Ontario, Canada Status: Offline Points: 5802 |
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Yes, that is another and probably cheaper option. You'd just have to hunt one down.
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Vince
1972 Ford GTS Sportsroof - Survivor, One Family car GTS.org Admin |
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DaleR09
New Member Joined: 23-July-2016 Location: Enumclaw, WA Status: Offline Points: 31 |
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I'm using an MSD 6A Ignition box on my 72 Ranchero GT , and used the MSD Tach Adapter for the factory tach to work. Works just great, fairly easy to wire in.
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'72 Ranchero GT Q code (Sold)
'63 F100 Unibody CV swap '03 Ranger 4X4 Stepside '03 F350 '14 Fusion AWD Titanium |
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72GTS351CJ
Senior Member Joined: 30-November-2010 Location: NY Status: Offline Points: 1481 |
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Dale do you have a part # for that by any chance
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72GTS Clint Eastwood Special
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DaleR09
New Member Joined: 23-July-2016 Location: Enumclaw, WA Status: Offline Points: 31 |
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part # 8920.
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'72 Ranchero GT Q code (Sold)
'63 F100 Unibody CV swap '03 Ranger 4X4 Stepside '03 F350 '14 Fusion AWD Titanium |
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DaleR09
New Member Joined: 23-July-2016 Location: Enumclaw, WA Status: Offline Points: 31 |
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'72 Ranchero GT Q code (Sold)
'63 F100 Unibody CV swap '03 Ranger 4X4 Stepside '03 F350 '14 Fusion AWD Titanium |
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