#1  
Old 01-17-2022, 11:56 AM
fairwayhit fairwayhit is offline
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Default Little help please- Wiring layout

I'm adding MSD Atomic EFI and MSD 6al to control the timing. I am also adding Dakota Digital gauges. In the future I will probably add Electric fans. After researching, it seems like my 63 amp 10si alternator might not be up to the task. I am thinking I'll upgrade to a 12si (100 amp) alternator.

Since I have the whole front end off, I'd like to re run all of the wiring while I have good access. I think I would also like to add a remote Ford starter solenoid although I could be easily talked out of that.

My stock engine harness has a crimpled splice for the power distribution, and fuse able links for some circuits. I am thinking about eliminating the splice and running everything through a bus/fuse block.

I read that I should have two buses. A "clean" bus for the EFI, ignition on/off, and dash gauges, and a dirty bus for the starter motor, fuel pump, electric fans and headlights.

The Atomic EFI and 6AL power and ground say that they have to be wired directly to the battery. I'll need relays for the fans and headlights, but the fuel pump is optional ( the fuel pump can be directly controlled by the Atomic - supposedly has a built in relay)

I am trying to figure out how to route all of these wires clean and neatly as well as make sure I have the proper circuits fused. Here are my questions:

1. Does the battery need a main fuse? If so, do the leads to the Atomic and 6al also need to be fused?

2. If I run the Atomic and 6AL directly to the battery do I really need a "clean" bus for the dash and ignition on/off? Both the EFI and 6AL need a switched ignition/ run connection. should those go through a relay or fuse?

3. If I eliminate the crimped splice distribution, what wires from the alternator need to be fused?

4. Where is the best places to locate the fuse/relay box and/or distribution buses in the engine bay?

  #2  
Old 01-17-2022, 12:25 PM
wbnapier wbnapier is offline
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I bought a a new stock wiring harness, then upgraded with the system I heard about on this forum: http://www.madelectrical.com/

In your case, I think it would be good. Read about it above.

You would have two distribution blocks. Main one and accessory one.

There is a fused wire that runs from the battery to the main junction block.

All other items get power from the main junction block, including 6AL, or accessory junction block, like lights and fans.

I did fuse / fusible link on fans and other places per instructions.

I have the following on relays:

1) Starter
2) Fuel pump
3) Fan 1
4) Fan 2
5) High beams
6) Low beams

__________________
1965 Pontiac GTO
455/469 w/ #48 Heads, '65 Tri-Power
9.25:1 CR
Stump Puller Cam
Muncie M22W 1st-2.56 2nd-1.75 3rd-1.37 4th-1.00
3.55 Rear Differential
Front: 225/60R15 Height: 25.6"
Rear: 275/60R15 Height: 28"
  #3  
Old 01-17-2022, 12:51 PM
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Stuart Stuart is offline
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You should mention the make model and year of your car.

  #4  
Old 01-17-2022, 04:18 PM
fairwayhit fairwayhit is offline
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Thanks Stuart,
It is a 1971 Lemans Sport Convertible, 400 Pontiac, TH350, with manual windows, and No AC

Thank you for the relpy wbnapier!

I looked at the Mad Electrical stuff and I am still trying to digest it all. A lot of good info there. I am still not sure I like the idea of using fusible links and single relay modules. It does seem like he is advocating replacing the splice power distribution with a bus (remote battery terminal).

It seems like a power distribution box (relays/ fuses) would be one central place for everything v. having the relays off by themselves.

I was thinking I might either use a Bussman box or repurpose a 2005 Impala engine fuse box to try to get all of the fuses and relays in one place for a cleaner look like most newer cars. Just trying to do this in the way that is cleanest.

Do you have a fuse on the main battery + cable? It looks like Mad Elect just calls for a fuse link between the alternator and starter solenoid.

It also looks like he wants the bus to be up by the horn relay so that the main dash power wire is short. Where did you mount your buses?

I was contemplating removing the horn relay entirely and running that relay through the power distribution box as well. There is actually a tap off the horn relay that powers the front light harness and it would seem like the front lights need to be on separate relays.

Sorry for all of the questions and thank you for all the help.

  #5  
Old 01-17-2022, 05:45 PM
wbnapier wbnapier is offline
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Here are the answers as best as I can do.

1) Does the battery need a fuse?

Answer: On the Mad Electric system, you have one wire that goes from the battery + terminal to the main junction block. This wire has a fusible link, so yes, it is fused. Other than the big + cable to the starter, this is the only wire off of the battery + terminal. See photo.

2) Ignition systems, like my 6AL, connect to the main junction block as well, not the battery + terminal. But, you could if you want to I presume. Mine is not fused. The idea of the Mad Electric system is that everything is routed to the main junction block or accessory junction block.

3) The main dash / power wire is connect to the main junction block as well, and yes, it has a fusible link. See picture.

4) I have a 1 wire alternator. It connects to the main junction block as well. See photo. Note that I run a ground wire for redundancy and I did the little brown wire and diode deal so my dash charge light would work like stock. See photo.

5) My accessory junction block is hidden under the battery tray. A wire brings power to this junction block from the main junction block on the fire wall.

6) Relays are hidden under the windshield washer fluid reservoir and battery tray. Yes, they could have been installed in a nice box as you suggest.

I chose to have my wires relatively exposed and the main junction block located right on the firewall. This was for ease of installation, maintenance, etc. as I am not a professional and that was more important than cleanliness or appearance.
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__________________
1965 Pontiac GTO
455/469 w/ #48 Heads, '65 Tri-Power
9.25:1 CR
Stump Puller Cam
Muncie M22W 1st-2.56 2nd-1.75 3rd-1.37 4th-1.00
3.55 Rear Differential
Front: 225/60R15 Height: 25.6"
Rear: 275/60R15 Height: 28"
  #6  
Old 01-24-2022, 09:42 PM
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mrennie mrennie is offline
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I rewired my main feeds as well as headlights using a lot of the info from the Mad Electric website.

Attached is a schematic I created to document my setup. You will note that I used a common junction block, and up-sized most of the feed wires on the charging side with the appropriate sized fusible links.

I also added headlight relays on the rad support with a larger feed.

Sorry if the schematic is a bit hard to read, it was a PDF that I converted to JPG so I could attach it.
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Michael


Oshawa built 1 option Judge basket case. 463, SD KRE 295's, CNC'd factory intake, Cliff's Qjet, Stump Puller HR cam, RARE RA manifolds, Pypes exhaust, T56 Magnum, McLeod RXT clutch, 3.42 12 bolt. 24 year project almost done...
  #7  
Old 01-24-2022, 11:34 PM
wbnapier wbnapier is offline
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Cool!

Similar to me...

1) Why not run your alternator power output wire to the junction block as opposed to starter terminal?

1) Why no starter relay?

2) What is RLO relay?

2) Do they recommend a HEI relay? I have a MSD 6AL, which I ran to the main junction block.

I pick up a '71 Ford F250 tomorrow. I went to Mad Electric's website and noted that they don't have any ford specific directions, which was a bummer.

__________________
1965 Pontiac GTO
455/469 w/ #48 Heads, '65 Tri-Power
9.25:1 CR
Stump Puller Cam
Muncie M22W 1st-2.56 2nd-1.75 3rd-1.37 4th-1.00
3.55 Rear Differential
Front: 225/60R15 Height: 25.6"
Rear: 275/60R15 Height: 28"
  #8  
Old 01-26-2022, 08:36 AM
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mrennie mrennie is offline
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Quote:
Originally Posted by wbnapier View Post
Cool!

Similar to me...

1) Why not run your alternator power output wire to the junction block as opposed to starter terminal?

1) Why no starter relay?

2) What is RLO relay?

2) Do they recommend a HEI relay? I have a MSD 6AL, which I ran to the main junction block.

Hello,

The alternator output is connected to the main junction block with #4 wire. The smaller #8 wire from the alternator to the starter (then to the battery) is mainly for charging the battery, not for supplying any load. I am using a CS144 140A alternator and as it has high output at low RPM, it should be supplying most of the electrical load, with very little if anything coming from the battery.

I did not use a starter relay as I am using a RobbMC mini starter and only wanted to modify the wiring to the extent required to get the results I wanted. My main issue with the stock wiring was the small charge wire and the fact that all fuse block loads are fed off the original splice with fusible link, so offloading as many of them to the junction block with their own fusible link or fuse was my goal.

RLO relay is the reverse lockout relay that I installed. I have a T56 Magnum and you cannot get into reverse without applying 12V to a solenoid on the transmission to release the shifter gate. I did not want a dedicated switch for this, so I connected the brake light power to a microswitch I added to the clutch pedal, and that controls the coil of the lockout relay. Wiring it to the junction block was intentional so I could put the trans in reverse even with the key off.

I am aware that most don't recommend a relay for the HEI...however...the factory wiring has resistance in the run position to protect the original points. This makes the factory wiring unsuitable for directly powering the HEI due to less than 12V when loaded down. But when you connect the factory wiring to a relay coil, the load is quite low and the relay coil has no issue being energized, making it simple to run a larger hot wire from the junction block through the relay contacts and to the HEI, without having to hack up the factory wiring too much. Also, what the schematic does not show is that the relays I used for HEI and RLO have a built in blade fuse holder for the load side and this makes it easy to disable them by just pulling the fuse when working under the hood.

__________________
Michael


Oshawa built 1 option Judge basket case. 463, SD KRE 295's, CNC'd factory intake, Cliff's Qjet, Stump Puller HR cam, RARE RA manifolds, Pypes exhaust, T56 Magnum, McLeod RXT clutch, 3.42 12 bolt. 24 year project almost done...

Last edited by mrennie; 01-26-2022 at 08:41 AM.
  #9  
Old 01-26-2022, 09:53 AM
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Scott65 Scott65 is offline
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I've used the basic Mad system for over 10 years now. It's been solid. I use a junction on the firewall for most of the engine and interior power, and one on the core support for power to headlight and fan and for a brief time electric water pump relays. I have an ecu that controls fuel and spark, and it's power comes straight from the cut off switch to a dedicated 4 position fuse panel for "clean" power. Pay special attention to your grounding scheme.
ETA: My battery is in the trunk, that's why I say I followed the "basic" Mad system. Some alterations for convenience, and appearance, etc.

ETA#2 I see you mention using the 12si alternator. I don't know your intentions for this vehicle, but if they involve high rpm, check and recheck your pulley ratio. A 10si with its metal fan can be slightly forgiving, the plastic fan on the 12si I've found is NOT. I had one explode, putting the shrapnel through my fiberglass hood. Keep the rpm under 18000 alternator rpms. I've posted about this before. I ended up with a metal fan Powermaster 150 amp, with a larger pulley. It charges fine in all conditions, and the rpms are in a safe place.

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  #10  
Old 02-06-2022, 08:22 AM
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RA66GTO RA66GTO is offline
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My setup is similar to the others, but different. No kits, other than the modified AAW harness. 10SI alternator, EFI is run directly to the battery, everything else is off a common stud on the firewall. Relays are for starter, fuel pump, AC clutch, and headlights. I can provide more info / pics if needed.
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File Type: pdf Power Distribution.pdf (15.6 KB, 77 views)
File Type: pdf Relay Center.pdf (10.3 KB, 42 views)

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