Paladin06
Well-Known Member
Not meaning to jack this thread but, I was not aware the direct wire from the alternator to starter relayed needed a fusible link. Guess I better correct that. Thx all and a Happy New Year to you.
Bypassing the Amp gauge - Question about the MAD Electrical method
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Yup. It's actually a pretty good strategy for a car with basic needs. Some weakness in execution, especially the a-body headlight circuit, but the concept isn't bad at all.
Strip away all the other systems and just looking at the power feeds its something like this.
R6 supplies the power when the engine is running.
A1 supplies power when the alternator isn't running, or can't keep up with demand and the voltage drops.
The primary power distribution point is the main splice.
When the key is in run position, the switch is a secondary distribution point making power available to the ignition, the switched side of the fuse box and the instrument panel.
When the engine is running and the alternator is above battery voltage, current flows pretty direct to primary distribution point.
There's no drop in wire size for fusible links and just one connection.
One way to reduce the load and losses at the connection is to make it better. Another is to add a parallel wire through a grommet. It can be spliced in or added to the ammeter connection with a ring terminal.
Current then flows in parallel.
Or if the battery is being recharged.
The concept comes apart when more loads are added to a distribution point in the engine compartment.
We can draw that later if anyone is interested.
A real life example of moving the primary distribution to the engine side is AMC's revamp of the SJ Jeep wiring in 1986.
I've posted that here: 1986 AMC Jeep SJ Charging and Inition Wiring Diagram
It's not the best execution, but the strategy is OK.
Notice every circuit is protected from the battery grounding out. In this case by using fusible links.
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Xtreamist
Well-Known Member
That is because the black alternator wire was still connected to the ammeter. It is ready to be connected to the starter relay now as I have up sized the wire and added a fuse link to it, it is not actually connected yet.
It is currently grounded with the volt meter on the firewall. It is a 4speed car and I know NHRA requires a safety switch, weather it be neutral or clutch. That switch is something else that has me concerned. The plug from the transmission has three wires coming out of it, one of them is brown and the other two I believe are black. It is as simple as connecting the brown to the post on the relay? If so, then what are the other two wires for?
It does.
Man, I really appreciate the effort you are giving this. I can do most of the wiring/splicing/adding new runs, ect. I just need some reassurance that I'm doing it right and that's why I'm asking....
Xtreamist
Well-Known Member
Great, sounds like I may have more questions regarding this issue...........
H'm. Someone else may know this off the top of their head. I know with the later 70's era torqueflites, the 3 prong switch on the transmission was one connection to ground in neutral; and two remaining for completing the reverse light circuit. Maybe manual transmissions were the same? Original '67 reverse light switches are on the shifter itself.
OK. So is possible the previous owner had the battery feed/charge wire connected to the ammeter?
If it looked like this, even with the partially charred fusible link, that completes the main circuits.
There's a few different ways this could be improved.
The ammeter is not the real issue, but the fusible link is pretty good clue that the amperage was too much for the circuit at one time, or cumulatively over time.
Removing both R6 and A1B would result in no connection to the original main power distribution point.
If you need something temporary
Run an auxillery R6 from the alternator output stud (Batt) to the starter relay stud, with a fusible link.
The original R6 line would then still connect to the main splice.
If the connection at P is in poor condition, then a parallel R6 to the ammeter stud could get you going.
Before coming up with a more permanent fix, it would be helpful to know how the alternator field gets its power.
Does the blue field wire to the alternator join at the regulator, or the ballast resistor, or a splice in between?
Following it further back, does it connect to the Ignition 1 wire at the ballast, then back to cavity N ?
But it might be wired to something else, like the new J (red)???
Knowing that, I think we can come up with a good plan, or two.
Yep, that is correct. The center pin of the 3 pin trans connector is the ground for the starter relay and the ends are the backup lights.
Xtreamist
Well-Known Member
This looks right, or at least the way it was. I have some thing disconnected now. Thank goodness I took pictures! The fuse link was really bad, barley hanging on by a thread. The connector was really melted too. This is why I was tearing into it to begin with. That's how I found that there was no red wire to the ammeter.If it looked like this, even with the partially charred fusible link, that completes the main circuits.
Blue alternator field goes to both the volt regulator, resistor, and to N. The green one goes to the volt regulator too. Neither is not spliced to the new red J.
I feel you should know a bit more about what I know on the car. 1967 Barracuda notch, originally a 273 car, now it has a 1973 Duster 340 in it with the A833 4 speed. The rear end is a Ford 9", not sure what car or year it came from though. So there are a few mix and match parts on it.
Some of the coolest cars I have seen have been mix & match cars. A lot of talent and creativity goes into those!
If there was no connection to the ammeter, then the ignition was running on battery and not getting recharged. I guess it would work that way until the battery ran down. Of course there must have been a wire at some point or the fusible link wouldn't have fried.
As there's no other connection between the battery and the alternator that we're missing - that's probably what we're looking at.
My guess is the connection and fusible link got hot because current was flowing through it all the time because the toggle switches tap in at the starter relay.
That means for the alternator to work, the key had to be in 'run'.
Here's what I think. Feel free to think different and say so - its your car!
Toggle switches: Don't see the advantage or need for any of them. If you do want to use some or all, that's fine.
#1. Tach. Don't see why this should be a seperate switch. Should be fused.
#2 Start. Running the full amperage all the way into the passenger compartment makes a long path when there is a relay available just for this purpose. If this is to be kept it should power the relay, not jump it. JMHO.
#3 Ignition Run (and start). Extra distance and connections than stock the way it was, but could be fine depending on final design.
#4. Aux Gage illumination. Don't see why this needs to be seperate from the other gage illumination. Should be fused.
Ignition switch: It's still needed the way the system is configured right now. It's definately possible to have the ignition switch do everything it used to. For a street/strip, I'm leaning that way.
Battery in the trunk. See what the rules say about cut off switch. The current layout is OK. We can also get a little creative if we see some advantage to doing it different.
I'll make some more suggestions later or in the morning.
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Xtreamist
Well-Known Member
The last time the PO had it running was just over 2 years ago, it has sat ever since, he was battling cancer and lost. I'm not sure what all he did to it but I'm slowly figuring it out.
I'm thinking the tach switch was just for the lights? I am fine with relocating it but I have to have it. I agree with you about using the ignition switch and relay the way they were designed to be used from the factory. Seems it would be less complicated.
I will need a cut-off switch since the battery is in the trunk per NHRA rules.
I'm thinking the tach switch was just for the lights? I am fine with relocating it but I have to have it. I agree with you about using the ignition switch and relay the way they were designed to be used from the factory. Seems it would be less complicated.
I will need a cut-off switch since the battery is in the trunk per NHRA rules.
The tach needs a power source to amplify the signal and move the needle. If its a fancy tach it will need power for the light, memory or whatever its got. I just can't think of a reason why it would be on a seperate switch.
Battery cut-off is straight forward. Battery cut-off with engine shut-off is a bit more complicated. Last time this came up we talked about having the switch ground out the engine side or using a relay.
Revision possibility 1. Lets not reinvent the wheel.
Generally return everything pretty close to stock routing and use ignition switch.
1. May need a new ignition switch and connector. Switches should be easy to buy if needed.
2. Manual cut-off switch in trunk for 0 to 4 gage wire. This assumes a basic open/closed switch for a single heavy wire routed as it is now.
3. Use the factory oil pressure and ammeter gages if they are working. They're easier to see. Arguably the Sun will be a little more accurate. Others may say if you want accurate pressure, go mechanical. I like gages. I have oil temperature and mechanical oil pressure in the accusump under the dash. I think oil temperature is a good addition for racing. A voltmeter is convenient - just keep in mind it only reveals voltage at the location it taps in at. Fuel pressure is another one some people like. I don't think its much use down low - I have a mechanical one that straps to the cowl outside the front window. Haven't used it for a long time, but when I doubts about delivery, it was helpful.
4. Keep the toggle switch for ignition. The only reason for this is the MSD Blaster 5900. Reading two different sets of instructions it seems the 5900 needs at least 12 Volts. They also say to use the ballast resistor for the coil if so equiped. Obviously the PO didn't do this. Its obviously OK to race this way. The question is whether the new coil will tolerate the heat generated from running at 12 volts for hours on end. If so, the Start and Run Ignition circuits can be tied together and the toggle eliminated.
A1 is certainly larger than 6 gage due the distance. You'll have to see how much larger.
A1A should 10 AWG or even 8 AWG because the location can get hot and its longer than the original routing.
Hot wires don't conduct as well. A wire with oil resistant, high temperature insulation would be best here.
Starter Relay. The owner may have bypassed this because it didn't work. May need a new one.
Fusible link. Same as stock, but connect one end to the stud with a ring terminal, the other with a connector to A1B.
A1B should be at least 12 gage. Its not carrying any more load that stock or going further distance.
But the connector at Z is damaged. Run A1B direct to the ammeter and use a ring terminal. Obviously use a grommet at the firewall.
Ammeter. If there's no sign of damage, I'd use it. Look for heat warping and gently check the studs to make sure they are not loose. If it is damaged, either use the Sun, or attach it on the alternator side. If its working, the ammeter will show whether the alternator is keeping up, or the battery is providing power (which is bad).
R6 Alternator output. If connection at P is OK, it still would be good to run a parallel 12 gage wire through the firewall to the ammeter alt terminal. This eliminates the firewall connection and the main splice when current is flowing to the battery for recharging. It provides a second route to the mainsplice for everything else.
Toggle 1- Tach. Power. Attach in fuse box. Tach will work when ever the ignition switch is in Run or Acc.
Toggle 2 - Start. Wont be needed if S2 is connected to a working starter switch and relay.
Toggle 3 - Blaster Power. May be needed - Could tap into any location that is hot in both Start and Run. This isn't great because it could accidently be left on. One easy location is the unused and unfused Hot terminal in the fuse box. Another would be the Alt. stud on the ammeter. A third location could be a splice into the power feed of the ignition switch.
Toggle 4 - Gage illumination. Tap into the instrument panel illumination at the fuse.
Oops. Forgot the Neutral Safety Switch. You know what to do there.
MSD 5900 Blaster. Shown here is assuming the coil is best off getting power through a ballast resistor.
If not, then toggle 3 can be eliminated entirely, and the ballast resistor can be replaced with a connector.
Generally return everything pretty close to stock routing and use ignition switch.
1. May need a new ignition switch and connector. Switches should be easy to buy if needed.
2. Manual cut-off switch in trunk for 0 to 4 gage wire. This assumes a basic open/closed switch for a single heavy wire routed as it is now.
3. Use the factory oil pressure and ammeter gages if they are working. They're easier to see. Arguably the Sun will be a little more accurate. Others may say if you want accurate pressure, go mechanical. I like gages. I have oil temperature and mechanical oil pressure in the accusump under the dash. I think oil temperature is a good addition for racing. A voltmeter is convenient - just keep in mind it only reveals voltage at the location it taps in at. Fuel pressure is another one some people like. I don't think its much use down low - I have a mechanical one that straps to the cowl outside the front window. Haven't used it for a long time, but when I doubts about delivery, it was helpful.
4. Keep the toggle switch for ignition. The only reason for this is the MSD Blaster 5900. Reading two different sets of instructions it seems the 5900 needs at least 12 Volts. They also say to use the ballast resistor for the coil if so equiped. Obviously the PO didn't do this. Its obviously OK to race this way. The question is whether the new coil will tolerate the heat generated from running at 12 volts for hours on end. If so, the Start and Run Ignition circuits can be tied together and the toggle eliminated.
A1 is certainly larger than 6 gage due the distance. You'll have to see how much larger.
A1A should 10 AWG or even 8 AWG because the location can get hot and its longer than the original routing.
Hot wires don't conduct as well. A wire with oil resistant, high temperature insulation would be best here.
Starter Relay. The owner may have bypassed this because it didn't work. May need a new one.
Fusible link. Same as stock, but connect one end to the stud with a ring terminal, the other with a connector to A1B.
A1B should be at least 12 gage. Its not carrying any more load that stock or going further distance.
But the connector at Z is damaged. Run A1B direct to the ammeter and use a ring terminal. Obviously use a grommet at the firewall.
Ammeter. If there's no sign of damage, I'd use it. Look for heat warping and gently check the studs to make sure they are not loose. If it is damaged, either use the Sun, or attach it on the alternator side. If its working, the ammeter will show whether the alternator is keeping up, or the battery is providing power (which is bad).
R6 Alternator output. If connection at P is OK, it still would be good to run a parallel 12 gage wire through the firewall to the ammeter alt terminal. This eliminates the firewall connection and the main splice when current is flowing to the battery for recharging. It provides a second route to the mainsplice for everything else.
Toggle 1- Tach. Power. Attach in fuse box. Tach will work when ever the ignition switch is in Run or Acc.
Toggle 2 - Start. Wont be needed if S2 is connected to a working starter switch and relay.
Toggle 3 - Blaster Power. May be needed - Could tap into any location that is hot in both Start and Run. This isn't great because it could accidently be left on. One easy location is the unused and unfused Hot terminal in the fuse box. Another would be the Alt. stud on the ammeter. A third location could be a splice into the power feed of the ignition switch.
Toggle 4 - Gage illumination. Tap into the instrument panel illumination at the fuse.
Oops. Forgot the Neutral Safety Switch. You know what to do there.
MSD 5900 Blaster. Shown here is assuming the coil is best off getting power through a ballast resistor.
If not, then toggle 3 can be eliminated entirely, and the ballast resistor can be replaced with a connector.
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