Factory tach wiring

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Murray

Murray

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Restoring a '68 cuda and am adding a factory tach to it. I have the tach and a repop wire loom for it. My question has to do with where the grey pickup wire to the distributor exits the firewall. If memory serves me, that one wire had its own exit hole (about 3/4"), high and center in the firewall, and then joined the main loom out to the distributor. Can anyone confirm that and give me a measurement or am I way off base?
 
Murray said:
Restoring a '68 cuda and am adding a factory tach to it. I have the tach and a repop wire loom for it. My question has to do with where the grey pickup wire to the distributor exits the firewall. If memory serves me, that one wire had its own exit hole (about 3/4"), high and center in the firewall, and then joined the main loom out to the distributor. Can anyone confirm that and give me a measurement or am I way off base?
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Should be a gray wire exiting the firewall. Do you have the rest of the harness? Also, are you running an MSD?
 
You pretty much got it. My factory tach is wired same way. Sorry car isn't here for pics or measurements.
Murray said:
Restoring a '68 cuda and am adding a factory tach to it. I have the tach and a repop wire loom for it. My question has to do with where the grey pickup wire to the distributor exits the firewall. If memory serves me, that one wire had its own exit hole (about 3/4"), high and center in the firewall, and then joined the main loom out to the distributor. Can anyone confirm that and give me a measurement or am I way off base?
Click to expand...
 
Interested in the same info. Is there more than 1 harness from the console tach to the distributor, and where did they go in a factory installation? Pics would be awesome!
 
The grey tach wire goes out through the center plug of the bulkhead plug in the letter "J" spot. It picks back up as a single wire outside and runs to the distributor. I don't believe it's in the harness, but Nella's car is not here to check that! I'll look the next time I'm at the shop!

IMG_4124.JPG
 
cosgig said:
The grey tach wire goes out through the center plug of the bulkhead plug in the letter "J" spot. It picks back up as a single wire outside and runs to the distributor. I don't believe it's in the harness, but Nella's car is not here to check that! I'll look the next time I'm at the shop!

View attachment 1715129308
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Geof...I'd appreciate that!
 
cosgig said:
The grey tach wire goes out through the center plug of the bulkhead plug in the letter "J" spot. It picks back up as a single wire outside and runs to the distributor. I don't believe it's in the harness, but Nella's car is not here to check that! I'll look the next time I'm at the shop!
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?? I think you'll find the grey wire is one of the senders, oil I think. The tach wire as normally been run out an add-on single wire grommet, separately from the bulkhead connector
 
67Dart273 said:
?? I think you'll find the grey wire is one of the senders, oil I think. The tach wire as normally been run out an add-on single wire grommet, separately from the bulkhead connector
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Correct. If they ever did add the tach wire to the standard harness it would likely have went though a previously unused port of the connector commonly referred to a wiper harness connector, just like the reverse lamp wires, and later the neutral safety wire, for examples.
I have a pic of a 67 B'cudas firewall showing that added hole, grommet, and wire saved on a disc here somewhere. I don't recall measurements added to it. So if a general reference would help, I'll hunt it. If my memory serves, the vacuum hose going to a performance indicator instrument went through the firewall in the same location.
 
67Dart273 said:
?? I think you'll find the grey wire is one of the senders, oil I think. The tach wire as normally been run out an add-on single wire grommet, separately from the bulkhead connector
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It's clearly marked on the schematic as coming from the tach, and going to the distributor. Although, I believe it has a black tracer on it. When I'm out at the car I'll check into it more.
 
cosgig said:
It's clearly marked on the schematic as coming from the tach, and going to the distributor. Although, I believe it has a black tracer on it. When I'm out at the car I'll check into it more.
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OK then... Oil sender wire is gray without a tracer.
 
cosgig said:
It's clearly marked on the schematic as coming from the tach, and going to the distributor. Although, I believe it has a black tracer on it. When I'm out at the car I'll check into it more.
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It may be grey, what I'm saying is it DOES NOT go through the bulkhead connector. It should be on it's own individual grommet. Look it up. The 68 Plymouth manual is at MyMopar
 
I'm not sure this answers the question you have and seems to disagree with most of the opinions stated above. I have a 67 Barracuda Formula S with the factory tach. I have a Year One "replacement" engine harness for 67 cars that have added electronic ignition. I snapped a couple of pics and you can see the grey/w blk tracer tach wire exits the bulkhead connector at the bottom and is "sistered" with one of the leads for the ECU. Sorry the pic is sideways...... dang it!

bulkhead_connector_edit.jpeg
 
That is indeed the case in '67. Maybe the OP has a split year early harness?
 
According to EBay auction #401456937121, the tach harness for '67-'74 A body has a large grommet on it, which tells me it goes through it's own hole in the firewall. See pic below...

s-l500.jpg
 
mopardude62 said:
I'm not sure this answers the question you have and seems to disagree with most of the opinions stated above. I have a 67 Barracuda Formula S with the factory tach. I have a Year One "replacement" engine harness for 67 cars that have added electronic ignition. I snapped a couple of pics and you can see the grey/w blk tracer tach wire exits the bulkhead connector at the bottom and is "sistered" with one of the leads for the ECU. Sorry the pic is sideways...... dang it!
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If everybody had a aftermarket modified harness....
 
Thanks for the help. Just got done studying '68 wiring diagram. At least for '68, there are two grey wires in the car. The grey wire going through the bulkhead connecter is the feed for the oil pressure sender on the block. It is grey with no tracer. Factory manual shows tach wiring as an independent add-on loom, added at the fuse block. The grey wire, no tracer, does feed through the firewall in it's own independent location, on its way to the coil. Great discussion, just need picture of exact location of that exit location.Thanks.
 
Heres pic of it coming across in the firewall tabs. Im trying to find a decent pic from drivers side. Note my coil is mounted in 6pack bracket. Ill keep looking for drivers side pic
Murray said:
Thanks for the help. Just got done studying '68 wiring diagram. At least for '68, there are two grey wires in the car. The grey wire going through the bulkhead connecter is the feed for the oil pressure sender on the block. It is grey with no tracer. Factory manual shows tach wiring as an independent add-on loom, added at the fuse block. The grey wire, no tracer, does feed through the firewall in it's own independent location, on its way to the coil. Great discussion, just need picture of exact location of that exit location.Thanks.
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20170620_160743.jpg
 
Found this other pic, grey wire coming across LH(pass side) Sorry its shitty quality of course lol and cant see exactly where it goes. Took this pic in 2016

20161110_122717.jpg
 
If I wasn't attempting to correctly clone OEM, I would buy a pair of Packard 56 terminals for the bulkhead connector and route this wire through the one of those unused ports. And of course male/female disconnect terminals just outside the firewall ( something very different in fitment from the fusible link connector ). This so the tack wire could be separated from the "wiper"/bulkhead connector. That is what they did with the 3 wire loom coming from neutral safety switch of automatic trans after all.
So my tach wiring would appear "standardized" instead of "add on" of 1 of the 3 possible instruments in this panels center pod.
The firewall hole and grommet method,,, that's for the performance indicators vacuum line.
 
You guys are great. This is a restoration, so it needs to be "correct". Should mention that this is a big block car. I don't think that would make a difference. Where does this grey wire exit the firewall?
 
Forgot to mention that I am using the original main wire loom, not a repop. So, main loom is original, tach wiring is repop. Car is all original including points. Am I crazy or what?
 
Murray said:
You guys are great. This is a restoration, so it needs to be "correct". Should mention that this is a big block car. I don't think that would make a difference. Where does this grey wire exit the firewall?
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The only difference would be the length of the trigger wire, being a big block has the coil near the front of the block, and a small block has the coil near the back of the block.

I'm hoping someone will come up with pics of the factory firewall exit area.
 
65Val said:
The only difference would be the length of the trigger wire, being a big block has the coil near the front of the block, and a small block has the coil near the back of the block.

I'm hoping someone will come up with pics of the factory firewall exit area.
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Anyone have a pic or 2 of the firewall exit location?
 
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