Hairpin units are commonly called 6 phase. They produce more output at idle and are more efficient than a conventional alternator. JS Alternators hairpin units feature premium bearings to withstand high engine rpm and utilize dual plate rectifier with 12 heavy duty diodes for improved cooling. Hairpin Units are a more reliable alternator to withstand high heat, high demand for your racing applications
This unit is a direct replacement for standard Delco 10DN, 10SI, and 12SI alternators, making it easy to install on most 1963-1985 GM vehicles. This direct replacement makes for an easy installation! To activate the alternator, you only need to connect a single wire from the provided pigtail to any ignition switched 12V+ source. This allows the alternator to turn on and off with the ignition switch. This unit is for a racing application, be sure to select what pulley design is needed for your vehicle in the drop down menu. Every 250amp alternator will automatically come with the OEM size pulley unless specified in your order notes.
All 12SI Applications will come with a 45 mm. (or 58mm for V Belt) pulley and will require installing a 1/2 inch - 1 inch shorter belt.
Fitment Guide:
| Make | Model | Engine | Year(s) |
|---|---|---|---|
| BUICK | All Early Models | Most Engines | 63-79 |
| BUICK | Gran Sport | All Engines | 65-67 |
| BUICK | Riviera | All Engines | 63-70 |
| BUICK | Skylark | All Engines | 63-79 |
| BUICK | Wildcat | All Engines | 63-70 |
| CADILLAC | All Early Models | All Engines | 63-85 |
| CHEVROLET | All Early Models | Most Engines | 63-85 |
| CHEVROLET | C10 Pickup | All Engines | 63-78 |
| CHEVROLET | Camaro | All Engines | 67-80 |
| CHEVROLET | Caprice | All Engines | 66-77 |
| CHEVROLET | Chevelle | All Engines | 64-73 |
| CHEVROLET | Chevy II | All Engines | 63-68 |
| CHEVROLET | Corvette | All Engines | 63-79 |
| CHEVROLET | El Camino | All Engines | 64-77 |
| CHEVROLET | Impala | All Engines | 63-77 |
| CHEVROLET | Malibu | All Engines | 64-77 |
| CHEVROLET | Monte Carlo | All Engines | 70-77 |
| GMC | All Early Models | All Engines | 63-85 |
| GMC | C15 Pickup | All Engines | 67-78 |
| OLDSMOBILE | All Early Models | V-8 | 63-85 |
| OLDSMOBILE | 442 | All Engines | 65-71 |
| OLDSMOBILE | Cutlass | All Engines | 63-76 |
| OLDSMOBILE | F85 | All Engines | 63-72 |
| PONTIAC | Early models | V-8 | 63-85 |
| PONTIAC | Firebird | All Engines | 67-70 |
| PONTIAC | GTO | All Engines | 64-71 |
| PONTIAC | Tempest | All Engines | 63-70 |
| PONTIAC | Ventura | All Engines | 71-77 |
We offer free shipping in the United States. Orders ship in approximately 3-5 business days, sometimes sooner. Many alternators are shipped the same day. Alternators that require a custom bracket can take 5-8 business days. If for some reason parts are on back order, we will notify you, but this is not common.
REQUIRED Installation Steps:
(Wear eye protection, remove jewelry/loose items, and allow car to fully cool before starting installation)
- Batteries must be fully charged before installation.
- Make sure vehicle is off and engine is cool.
- Disconnect the negative cable from the battery/batteries.
- Disconnect all other wiring from the alternator.
- Remove the belt (note the belt routing before removing).
- Remove the bracket bolts and original alternator.
- Mount the new alternator. Typically the original bolts will be used.
- The belt must be replaced with a .5 to 1-inch shorter belt when installing a high output alternator, unless otherwise specified.
- Install the new belt. Make sure the routing is correct and the belt is aligned with all pulley grooves.
Grounding (Uni-body frame warning): Many newer vehicles have “uni-body” or sheet metal frame structures with no traditional “full frame”. Because of seams and adhesive attached body components, additional steps may be required for proper chassis grounding. Choose the location on the sub-frame with the thickest metal possible. If there is lower than spec charging voltage at the battery, move ground connections or add additional ground cables to different frame components.
*** WARNING *** Keep all electrical wiring at least 12” away from heat sources to avoid fire of the cable jacket!
There are THREE Regulator styles. Read each to determine which one your alternator has and read its the included notes:
- Factory Plug: The factory harness can be plugged into the new regulator. Be sure factory plug is clear of all debris and fully snapped into place in regulator.
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Turn On Single Wire Alternators: Follow this step ONLY if we shipped a pigtail plug with your alternator. Connect the excite wire (L) to a 7v to 15v ignition power source and connect the sense wire (S) directly to positive post on alternator. See picture of the Pigtail Plug below.
PIGTAIL PLUG
- Self Excite Alternators: Self-exciting or better known as “one wire” alternators will have NO plug on the alternator, and the OEM alternator harness plug will be left disconnected. This type of alternator requires only the positive and negative battery cables to be connected to the alternator to function. These alternators are internally regulated and will turn themselves on and off with engines rotation and regulate their own charging voltage. (This may cause battery light to come on).
Gauges
It is highly recommended you add a dash mounted volt gauge.
- Connect the battery ground and confirm all other electrical connections are complete.
- Confirm the belt path is correct and clear of obstacles.
- Before starting the vehicle confirm that the battery is charged, as starting the vehicle with a discharged battery can damage the alternator.
- Use a battery charger to charge the battery first if voltage is inadequate.
Ground Path Resistance Test
If resistance is greater than 0.1V confirm the following:
- Confirm that all paint, anodizing, or rust is removed, and the connections are to bare metal.
- Make certain all terminals are tight to the wire.
- Make certain the ground wire is of proper size.
Charge Path Resistance Test
If resistance is greater than 0.1V confirm the following:- Make sure alternator charge post nut is tight.
- Make sure charge wire is proper size.
Battery Recommendation
- 2000 watts: upgrade main battery, 1 rear battery
- 3500 watts: upgrade main battery, 1-2 rear batteries
- 5000 watts: upgrade main battery, 2-3 rear batteries
- 7500 watts: upgrade main battery, 3-4 rear batteries – 2 alternators
- 10,000 watts: upgrade main battery, 3-5 rear batteries – 2 alternators
Big 3 Wiring
All factory connections need to remain connected. |
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Positive 1/0 100% Pure Copper Cable |
Connect from the positive stud on the alternator to the positive on the battery |
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Ground 1/0 100% Pure Copper Cable |
Connect from alternator mount bolt to frame/chassis |
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Ground 1/0 100% Pure Copper Cable |
Connect from negative on battery to the frame/chassis |
Big 3 Wiring Kit With RVC
All factory connections need to remain connected. |
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Positive 1/0 100% Pure Copper Cable |
Connect from the positive stud on the alternator to the positive on the battery |
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Ground 1/0 100% Pure Copper Cable |
Connect from alternator mount bolt through the GROUND SENSOR LOOP to the negative on the battery |
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Ground 1/0 100% Pure Copper Cable |
Connect from negative on battery to the frame/chassis |
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Depending on the application you may need to run a distribution block for better connections (if you have too many upgraded wires that cannot connect directly to the battery terminals). If you have any questions feel free to email or call us as we are happy to help:
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Looking to return an item? Read our return policies and fill out the Return & RGA Requests Form linked here and at the top of our website.
Warranty Information:
All JS Alternators come with a 1 year warranty. Powder coat is non-refundable as it is custom powder coated per order. Original invoice or copy of original invoice must be included in order to receive warranty service. This warranty covers repairs to the JS Alternator only and does not include other parts on the vehicle. This warranty does not include any labor expenses for installation or uninstallation of the alternator. Warranty only covers testing and repair of the alternator and does not guarantee an automatic replacement alternator.
The following will void any and all warranties:
- Improper installation
- Improper belt length
- Improper wiring (no installation of big 3 wiring upgrade kit)
- Changing parts on the alternator, including pulley and regulator
- Any unauthorized modifications (this includes disassembling the alternator)
- Painting or powder coating the alternator by an outside party
- Misuse or abuse of the alternator (not having adequate battery reserve for demand of power draw)
- If repairs have been completed by anyone other than JS Alternators
This warranty does not cover other parts or equipment on the vehicle and it does not cover labor expenses related to the removal or installation of the alternator, nor rental cars or any other expenses incurred.
SHIPPING POLICY
- Customers will be liable for return shipping costs for alternators repaired under warranty.
- JS Alternators will cover shipping costs of the alternator back to the customer after warranty repair if still inside the 1 year warranty.
- Customers outside of the continental US will be responsible for return shipping costs.
- PLEASE PACKAGE YOUR RETURN CAREFULLY TO AVOID DAMAGE FEES!
- Costs associated with repairing damage caused by return shipping will be the responsibility of the customer.
RETURN POLICY
PLEASE COMPLETE AND SUBMIT THE RGA REQUESTS AND RETURN FORM BEFORE RETURNING ANY PRODUCTS. CUSTOMERS MUST RECEIVE AN EMAIL CONFIRMATION BEFORE RETURNS ARE AUTHORIZED.
All custom ordered alternators, including pulley, regulator, powder coating, and custom housings, are NON-RETURNABLE.
All JS Alternators are custom built to order. New and unused standard alternators may be returned within 90 days of purchase but will be subject to a 10% restocking fee after full inspection. After 90 days from the purchase date have passed, all orders are non-refundable. If the alternator has been installed and used it is non-refundable.
Big 3 Kits are NON-RETURNABLE
"Universal" fit Alternators are NON-REFUNDABLE
Frequently Asked Questions
Orders ship in approximately 5-15 business days, sometimes sooner. Alternators that require a custom bracket can take 10-25 business days. If for some reason parts are on back order, we will notify you, but this is not common. If payments are being made on an order, your order will start processing when the order is placed.
We offer lifetime warranty on alternator labor and a one year warranty on parts. All orders are heavily wrapped for shipping with several layers of big bubble wrap and two layers of boxes along with a Fragile sticker on the box. If you have to ship your alternator back, please be sure you wrap it the same way to prevent further damage. See more details on our warranty page.
Each of our high output alternators come with smaller overdrive pulley. This pulley is made to increase low RPM charging for maximum output. It is custom for the diameter of the overdrive to be less than your factor pulley, depending on the kind of vehicle you own. For this reason, unless otherwise specified, you will need at least a 1/2 inch shorter belt. You can purchase this from any auto parts store. In using the belt and the pulley system, ensure that each part of the pulley system is free of oil or grease, this will help its efficiency.
It is important to make sure that the small regulator plug that is located on the back of the alternator is well plugged in for the correct functionality. Do not forget to plug it in completely, try not to jam the plugs in backwards, and avoid pinching it in order not to create a short. For more information on regulators and wiring see installation instructions.
Our high output alternators come with an overdrive pulley. The pulley is designed to improve low RPM charging so that it yields maximally. Do not change this overdrive pulley out with a larger diameter pulley. When alternator pulley diameter is increased, the output amperage decreases. Changing the pulley will void all warranties
As promised to all our customers, our products are fully tested ensuring their outstanding performance before shipping. In our experience through the years, it is in many cases not the alternator itself. You must ensure you consider a few possible concerns in your troubleshooting – please read the instruction manual thoroughly.
The reason could be one of two things: Either the plug is wired incorrectly or the computer is sensing the higher voltage and causing the battery light to come on even though the alternator is charging properly. Please refer to the instruction manual tab on the website for specific instructions that will help you with wiring. For some older vehicles, the factory style regulator is not available with the hairpin style alternator. This is why your high output alternator will come already “upgraded” with the 15 volt regulator. It will have an oval plug which requires splicing into the factory plug. This is a simple ,fast step and these instructions are detailed for you in the instruction manual.
Yes, please visit prismaticpowders.com then scroll to the bottom of the page. Select color match and enter your information. When ordering on the JS Alternators website, select the custom prismatic powdercoating color option, and include the specific color you chose from prismaticpowders.com. There is an additional $10 charge for custom colors, and the custom colors are required to come from prismaticpowders.com
We use your vehicles stock voltage unless requested otherwise.
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