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.

Connections Of Frame/Body: Clean all metal surface of any paint or rust with a wire brush or die grinder. Use a conductive corrosion inhibitor available at any electrical parts supply store.

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:

1. 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.
2. 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
3. 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

 

 

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