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Discussion Starter #1
I'm replacing the cluster with new Classic Instruments gauges. I'm curious what I do with the ammeter wires and the constant voltage regulator wires. If I unhook the ammeter wires, can I just leave them unattached and zip tied out of the way?

Same question for the black/green constant voltage regulator wires?

Decided this should be my coronavirus project.
 

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Yeah, if the new gauges are 12+/- volts instead of 5 volts, they don't have to be connected to the CVR and the ammeter wires don't have to be connected but I would wrap them well so they don't arc on anything. You could possibly get a new ammeter gauge or a voltage gauge, or perhaps even set them up to close a relay for a warning in case of a charging system failure.
 
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Discussion Starter #5
Thanks everyone. I'll shrink wrap the ends and tuck them away.

@myfirstcar66 how do you set up a warning light?
 

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I slide a piece of heat shrink tubing onto the end of the unused wire, leaving a little sticking out of the end of the wire (so the end of the wire isn't showing). Then I shrink it, and while still hot pinch the end closed.
I do sorta the same thing. Leave a bit more sticking out, shrink, fold the sticky outty bit back, another piece of heat shrink over it all. Probably overkill though.
 

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Discussion Starter #7
Another question, and I know I should call Classic Instruments, but do you think my sending units for the temp and oil will work with the instruments? The kit from Classic Instruments came with new sending units.

One thing the instructions said was NOT to use any thread sealant on the sending units. I noticed that when my engine builder assembled things, he used thread sealant on both sending units. Could this cause issues grounding and cause some irregularities with the oil pressure readings?
 

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Put a female bullet connector on the IVR feed wire... you can use it again at a later time as an Ignition "ON" power feed.

You can use either of the ammeter wires to connect a voltmeter... the BLK/YEL one splices directly to the alternator output wire and the other one to the starter solenoid common "hot". Otherwise, I'd probably do the same.... "cap" them with a female bullet. Since neither is circuit-protected if you don't think you'll ever reinstall an OEM gauge cluster you may want to consider disconnecting the wires from their power sources.... the BLK/YEL is spliced into the alternator output wire and the other one is connected at the solenoid. Disconnect them and terminate them somewhere in the harness.
 

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Another question, and I know I should call Classic Instruments, but do you think my sending units for the temp and oil will work with the instruments? The kit from Classic Instruments came with new sending units.

One thing the instructions said was NOT to use any thread sealant on the sending units. I noticed that when my engine builder assembled things, he used thread sealant on both sending units. Could this cause issues grounding and cause some irregularities with the oil pressure readings?
The sending unit question depends on the requirements of the gauges provided. If they are 73-10 ohm gauges then the existing sending units should work fine. My guess is that, since they provide senders as well, they are probably "GM spec" or 240-33 ohm. I'd use the new senders which, since they are NPT threads, which are tapered, should not need sealant. If you are determined to use a sealant, use a liquid/paste and do so sparingly.
 

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Discussion Starter #10
Thanks @Woodchuck for the info. So the instructions say to just attach a 12V feed to the volt meter. If I use the YLW wire or the RED wire for the ammeter, would that tell me voltage output from the alternator? Would this be a different reading than if I used a different 12V source?

The instructions say to use a dedicated switched source for the speedo. I think I'll use the feed from the IVR to power the speedo and feed the gauges from my circuit panel.

I'd like to cut into the harness as little as possible, just in case. So I think I'll wrap up the ends of the non used wires.
 

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Thanks @Woodchuck for the info. So the instructions say to just attach a 12V feed to the volt meter. If I use the YLW wire or the RED wire for the ammeter, would that tell me voltage output from the alternator? Would this be a different reading than if I used a different 12V source?

The instructions say to use a dedicated switched source for the speedo. I think I'll use the feed from the IVR to power the speedo and feed the gauges from my circuit panel.

I'd like to cut into the harness as little as possible, just in case. So I think I'll wrap up the ends of the non used wires.
Using one of the old ammeter wires will get you battery voltage, but at a source where it has not part of another circuit and subject to the additional resistance present in that circuit so, in effect, a more "true" reflection of actual battery voltage. Either will be just as accurate as the other. However, bear in mind that those wires are "hot" all the time, so your gauge will be "live" all the time, even with the key in the "OFF" position.
 

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Discussion Starter #12
Using one of the old ammeter wires will get you battery voltage, but at a source where it has not part of another circuit and subject to the additional resistance present in that circuit so, in effect, a more "true" reflection of actual battery voltage. Either will be just as accurate as the other. However, bear in mind that those wires are "hot" all the time, so your gauge will be "live" all the time, even with the key in the "OFF" position.
Got it, thanks. I think I'll cap the old ammeter wires. The instructions specifically say to use a switched source for the voltmeter so I'll do that.
 

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@ophthos the 65s had an inductive ammeter and had a "BAT" light that would come on so between the wiring diagrams and knowledgeable VMF members more familiar with those may be able to tell you how to hook up that charging system trouble lamp.
 
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