Larger alternator amp/volt gauge help

[Coronetguy68]

Hey guys I'm new here I've tried searching a bit but I cannot find exactly what I'm looking for. I have a 1968 Coronet, the car was fully restored years back and everything replaced. I'm upgrading to a higher amp alternator, however it seems like this car is wired like a 1970 and up with the silver box style voltage regulator. It's a two wire alternator setup, now for my big issue at hand. I took apart the cluster and retro fitted a volt gauge where the amp meter was and made it look factory. Everything I read it says to put both the wires that were on the amp meter together. Now I was tracing wires to follow those using continuity test. The red wire, I get a signal off the positive battery cable, now the black one gets signal on any ground. Bolts under the dash ect.. So obviously I can't hook the two together but I can't for the life of me make sense why the car would be wired this way? It does make my life easier just hook it to the volt gauge done, or am I missing something here. It also begs the question did the guy who restored the car have that as a volt gauge. I appreciate any help in advance

 

[Gold Rush]

On an original amp meter the red wire goes to the alternator output and the black wire to the battery positive output. That is how the system determines battery charge/discharge condition which is what the meter is supposed to do. The volt meter will have one connection to the battery and one to ground. Double check the black wire using a volt meter and see if there is battery voltage on that wire. Using continuity as your test might be misleading. Could be reading through a light bulb to chassis ground. If not, I'd do some investigating before hooking the new volt meter into the circuit.

 

[72RoadrunnerGTX]

That's backwards, the red ammeter lead goes to the battery, the black is the feed from splice1 then to alternator. To OP, are you assuming the black wire is grounded or has it been tested?

 

[pnora]

On an original amp meter the red wire goes to the alternator output and the black wire to the battery positive output. That is how the system determines battery charge/discharge condition which is what the meter is supposed to do. The volt meter will have one connection to the battery and one to ground

Thats wrong. Red goes to battery and black goes to alternator.

 

[Nacho-RT74]

As mentioned is backwards… althought the only issue with reversed wires is also a reverse reading

To OP… if the car was working with the mentioned red and black wires ( both 12 gauge ) untill now with the ammeter, both are still positive, just one coming from batt and the other from main splice where power is spreaded everywhere to the car, alt included which becomes on the main power source once engine is running to feed that splice.

NOW, why the black wire can get a ground reading? Any constant BATT source is actually feeded from the alt side splice. This includes some bulbs like dome light or some other courtesy light. The bulbs filament closes the circuit to ground from any positive source. The bulbs lights on once the positive goes throught the filament. A bulb is somehow a “controlled short” to ground to make its job. So its should be somehow normal if reading for somekind of “continuity” between black amm wire and chassis ground.

You are mostly sure checking with door open. Check if closing the door the ground continuity reading at the amm black wire dissapears. The door jam switch should cut this ground reading with door closed, like when dome light goes off closing the door.

 

[pnora]

Hey guys I'm new here I've tried searching a bit but I cannot find exactly what I'm looking for. I have a 1968 Coronet, the car was fully restored years back and everything replaced. I'm upgrading to a higher amp alternator, however it seems like this car is wired like a 1970 and up with the silver box style voltage regulator. It's a two wire alternator setup, now for my big issue at hand. I took apart the cluster and retro fitted a volt gauge where the amp meter was and made it look factory. Everything I read it says to put both the wires that were on the amp meter together. Now I was tracing wires to follow those using continuity test. The red wire, I get a signal off the positive battery cable, now the black one gets signal on any ground. Bolts under the dash ect.. So obviously I can't hook the two together but I can't for the life of me make sense why the car would be wired this way? It does make my life easier just hook it to the volt gauge done, or am I missing something here. It also begs the question did the guy who restored the car have that as a volt gauge. I appreciate any help in advance

View attachment 1634451

You will get continuity on the black wire to ground. You would have to isolate all the components off that circuit not to get a reading. Every component will have continuity to ground. Simple way to explain is take a single contact bulb and ground the ground leg. Then take a reading off the other positive leg. You will get a reading through the bulbs filament.

 

[Nacho-RT74]

I was editing and adding that info on my reply while you were replying LOL…

 

[Gold Rush]

I was editing and adding that info on my reply while you were replying LOL…

MY Bad!! I KNEW THAT!! Got the ball rolling on sorting out his issue. I agree the continuity to ground is likely coming through light bulbs

 

[Coronetguy68]

Ok perfect I got some more things to look at when I get back home. I really appreciate the quick replies! I'm not super great when it comes to wiring I just don't want to mess something up or burn the car down. The light bulb continuity makes sense why I'd be seeing a ground I hadn't even considered that. I have also read that the buldhead likes to burn up. It's currently not melted, would you recommend leaving it as is or bypassing that connector due to the higher amps running through it?

 

[pnora]

Ok perfect I got some more things to look at when I get back home. I really appreciate the quick replies! I'm not super great when it comes to wiring I just don't want to mess something up or burn the car down. The light bulb continuity makes sense why I'd be seeing a ground I hadn't even considered that. I have also read that the buldhead likes to burn up. It's currently not melted, would you recommend leaving it as is or bypassing that connector due to the higher amps running through it?

You should consider by passing the bulkhead with the alternator wire. Its only 12 gauge so its light duty for a bigger alternator. Painless makes a nice kit. Painless Wiring

 

[Nacho-RT74]

Ok perfect I got some more things to look at when I get back home. I really appreciate the quick replies! I'm not super great when it comes to wiring I just don't want to mess something up or burn the car down. The light bulb continuity makes sense why I'd be seeing a ground I hadn't even considered that. I have also read that the buldhead likes to burn up. It's currently not melted, would you recommend leaving it as is or bypassing that connector due to the higher amps running through it?

Check the stickied thread on this section of the board.

The higher amps running throught the wiring is relative. Your car will suck the same amps no matter how much output gets from any of the sources (alt or batt) depending on how many accs you have turned on. A bigger amps capacity to source will guarantee a better &/ or more stable voltage rate and less discharge reading if the bigger amps capacity to source comes from alt. Less discharge reading also guarantees less load running throught the charging circuitry to recharge or keep charged the batt. So, somehow, a bigger capacity alt could be even safer for the charging system network, since the batt will be less time requested to source and the load lost by the batt won’t be claimed back as a constant stage (charge reading). This cuts a bit the load coming and going from/to the batt, reducing the total demand for load when there is no charge constantly requested (zero/center reading at amm)