How to install a high output Ford 3G alternator into older Fords?
Upgrading to a high output Ford 3G alternator is a popular modification for older Ford vehicles. This alternator provides improved charging capacity, making it ideal for vehicles with additional electrical demands such as upgraded sound systems, auxiliary lighting, or other accessories. In this guide, we’ll walk you through the steps to install a Ford 3G alternator into your classic Ford.
Why Upgrade to a Ford 3G Alternator?
The Ford 3G alternator is a significant improvement over older alternators found in classic Fords. Here are some reasons why you might consider this upgrade:
- Higher Output: The 3G alternator provides more amperage, ensuring your vehicle’s electrical system has sufficient power.
- Improved Reliability: Modern design and components make the 3G alternator more durable and efficient.
- Better Charging at Low RPMs: Unlike older alternators, the 3G performs well even at idle speeds.
Tools and Materials You’ll Need
Before starting the installation, gather the following tools and materials:
- Ford 3G alternator
- Alternator mounting bracket (if required for your specific vehicle)
- Basic hand tools (wrenches, sockets, screwdrivers)
- Wire cutters and crimpers
- Heavy gauge wire (4 AWG or 6 AWG recommended)
- Fuse holder and appropriate fuse (150A recommended)
- Multimeter
Step-by-Step Installation Guide
Follow these steps to install the Ford 3G alternator into your older Ford:
- Step 1: Disconnect the Battery
Before working on the electrical system, disconnect the negative terminal of the battery to prevent any accidental short circuits.
- Step 2: Remove the Old Alternator
Loosen the belt tensioner and remove the drive belt. Then, unbolt the old alternator and disconnect the wiring harness.
- Step 3: Install the 3G Alternator
Mount the new 3G alternator using the existing bracket or a new one if required. Ensure it is securely bolted in place.
- Step 4: Upgrade the Wiring
The 3G alternator requires heavier gauge wiring to handle the increased amperage. Run a 4 AWG or 6 AWG wire from the alternator’s output terminal to the battery, incorporating a fuse holder with a 150A fuse for safety.
- Step 5: Connect the Voltage Regulator
The 3G alternator has an internal voltage regulator. Connect the wiring harness to the alternator, ensuring all connections are secure and properly insulated.
- Step 6: Reinstall the Drive Belt
Reinstall the drive belt and adjust the tension according to the manufacturer’s specifications.
- Step 7: Test the System
Reconnect the battery and start the engine. Use a multimeter to check the voltage at the battery terminals. It should read between 13.5V and 14.5V with the engine running.
Final Thoughts
Installing a high output Ford 3G alternator is a practical upgrade for older Fords, especially if you’ve added modern electrical accessories. With the right tools and careful attention to detail, this installation can be completed in a few hours. If you’re unsure about any step, don’t hesitate to consult a professional mechanic or reach out to us at Kevin’s Autos for expert assistance!
Frequently Asked Questions
Can I use a different alternator?
Choosing the wrong one won't work with your vehicle in most cases. Size. Of course, physical dimensions make a huge difference in whether an alternator will fit in place of your old one. The mounting bolts need to line up, plus the housing needs to fit in place of the old one without interfering elsewhere.
How many amps is a Ford alternator?
The alternator produces a maximum of 250 amps and will produce a minimum of 160 amps continually at low idle speeds and maximum output above 1800 engine RPM.
What do I need for a high output alternator?
Before beginning the installation of a high output alternator, all necessary tools must be obtained. This includes a socket and ratchet set, wrench set, belt tensioner tool, safety gear such as gloves or eyewear, and a memory saver.
How many amp alternator do I need for 2000 watts?
100-150 amps
They /do/ make alternators that can handle 2000 watts with no problem. A typical alternator is 100-150 amps, so 1200 to 1800 watts. Most AC loads are not going to pull the full 2000 watts, so it is likely the whole point is moot.
What is the alternator specs for Ford 3G?
Stock small case 3G units usually had an output of about 90 amps, the large case puts out about 130 amps. Our 3G series large case alternators start at 130 amps and go up to 250 amps with our Quicktifier Dual and Triple Rectifier System.
What are the downsides of a high output alternator?
Disadvantages Of High-Output Alternators
The most notable disadvantage is the potential for overheating due to increased amp load on the system.
How many amps is a 3G alternator?
Some are rated at 90 or 95 amps, and may be as low as 75 Amp. The alternator in my 91 Escort has the typical 3G design, but has a smaller case, and is only rated at 75 Amps.
Do I need to upgrade wiring for a high output alternator?
If you're upgrading your stock alternator to a high output alternator, it is required to upgrade your wiring to a big 3-wiring upgrade kit. A common myth is that you don't need to upgrade your wiring if you aren't running an aftermarket car audio system or other aftermarket products. However, this is not true.
What are the three wires on a Ford alternator?
3 Wire Alternator Diagram
There are three key wires in the loop: a positive wire for the battery, a sensing wire for voltage, and an igniting wire. The ignition input wire is linked to the engine.
