More Power To Ya: Wiring Upgrades for Older Carsby Stan Martin |
Here's a tip for older Mopar owners: if you are running a 60 amp (or higher) alternator in your car, you should probably add special wiring to handle the extra load. I noticed recently that some of the engine compartment wiring harness connectors on my '73 Dodge Dart (225 slant 6) were looking a little melted. After studying the wiring diagrams, I discovered that (in 1973, per the Dodge Factory Service Manual) a 60 amp alternator was considered "heavy-duty" and was optional - and the wiring was slightly different for that option. Back then, 35 amp was standard. Nowadays, 60 amp would be standard (or even small) and 100 amp common. I have been running a 60 amp alternator for about 8 years now.
I got all the parts for this modification at NAPA and used crimp-type connectors so there was no soldering. The hardest part was hooking onto the ammeter - I tried to do it from below the dash but finally gave up and pulled the instrument panel.
After adding the extra wiring, my car charges MUCH better! This wiring basically bypasses the normal engine compartment connectors to give a more direct, low-resistance path from the alternator, through the ammeter, to the battery. If you use a 60 amp (or larger) alternator without this wiring, you are in danger of overloading the factory harness.
| Disclaimer |
I am offering this as a helpful suggestion for fellow auto enthusiasts and hobbyists. Nothing in this description should be interpreted as offering engineering services to the public. All responsibility for validity of wiring and vehicle safety rests with the vehicle owner. Do not undertake this project if you are not comfortable with assuming that responsibility.
| Approximate Parts List |
- 16 gage red wire, about 8 ft.
- 16 gage black wire, about 12 ft.
- 16 gage fusible link. This is a length of wire about 6 in. long. Factory style has a little plastic "flag" molded onto it which says "Fusible Link". Ideally, the wire insulation should be red but color is not crucial.
- Squeeze-tap connector, 16 gage. This is a connector designed for tapping into an existing wire. When you squeeze it around the existing wire, a little pointy contact pierces the insulation. The connector contains a female receptacle for plugging in your new connection.
- Bullet connector, 16 gage (mates with above)
- 16 gage crimp-on "loop" or "ring" style terminals (approx. 3).
- 16 gage butt-connector.
Alternatively, you may prefer solder-type terminals, in which case you'll need those, also solder and electrical tape or heat-shrink tubing.
| Tools |
- Wire/connector crimp tool
- screwdriver
- wire strippers or knife
- small socket wrench or open end wrench (for removing ammeter terminals); probably 5/16" or 1/4".
- alternative tool: soldering iron
| The Process |
Before you begin: you must disconnect the positive (red) lead from the battery. Failure to do so may result in injury!!
Basically, the extra wiring is:
1) A black wire (16 gage or thicker) from the alternator to the "-" terminal of the ammeter. Feed the wire directly through the firewall (I fed it through the grommet for the speedometer cable).
2) Then a red wire (also 16 ga.) from the + ammeter terminal, back through the firewall, through a 16 ga. fusible link, to the "+" terminal of the starter relay.
I used a squeeze-tap connector on the alternator feed just below the firewall connector, where it wasn't obvious, to tap into the alternator current before it passed through the offending connector. Then a bullet-type terminal for the black wire (plugs into the socket on the squeeze-tap), so it's still possible to remove the engine-side part of the harness without cutting anything. A ring-type connector was used at the ammeter.
The fusible link was conveniently wired into the system at the starter relay. A ring-type connector was used to fasten one end of the fuse link to the large nut on the starter relay which connects to the positive battery terminal. A butt connector was used to connect the fuse link to the red wire. The red wire was then fed through the firewall to the ammeter, where a ring connector was used.
The fusible link is a safety factor and was present in the optional 60-amp factory wiring. This is to prevent dangerous overheating and possible fire if a short develops in this wiring, since this wiring connects directly to the battery. Do NOT add this wiring without it!
This duplicates the factory stock wiring (per the '73 Dodge Dart factory wiring diagram) as close as reasonably possible. A purist will note that this might cost you show points, if the judges notice the non-stock modifications. However, those astute judges would also likely notice that your car doesn't have the option code for the 60-amp alternator you've installed. If you're in this for pure show, put a stock 35-amp alternator on there! But if you're using your Mopar for daily use and want it to charge "better than new" with a high-output alternator, make your wiring harness like they made 'em at the factory!
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Stan Martin's 1973 Dart Swinger with slant six automatic - 201,355 miles and still going strong! |
+----------------------------------------------------------------------+ |Stan Martin, P.E. (stan.martin@acm.org) | |======================================================================| | S/W Sys Engineer: Raytheon TI Systems http://www.raytheon.com | | Cert. Teacher: Couple-To-Couple League http://www.ccli.org | | Disclaimer: The views expressed here are mine; not anybody else's. | | Unless I say they are. Take that, legal demons from Heck! | +----------------------------------------------------------------------+
