JEGS HEI Distributor Instruction Manual

1. Product Overview

The JEGS HEI Distributor is designed for Small Block and Big Block Chevy engines, featuring a fully adjustable vacuum/mechanical advance system. It includes a red cap with male brass terminals and a steel gear. This unit is equipped with a 65,000 Volt Coil to provide a hotter spark for maximum performance and improved economy.

Figure 1: Front view of the JEGS HEI Distributor.

Key Features:

• Adjustable vacuum advance for precise timing control.
• High voltage 65,000 Volt coil for enhanced spark energy.
• Coated weights for improved corrosion resistance.
• Welded weight pins for increased durability.
• Standard-type steel distributor gear, suitable for hydraulic or solid flat tappet camshafts.
• Utilizes OE 0.491" diameter shaft.
• CNC aluminum body for long-lasting operation.
• Solid brass terminals for reliable electrical connections.

Figure 2: Side view of the JEGS HEI Distributor, highlighting the vacuum advance unit.

2. Compatibility

This HEI distributor is a direct replacement for a wide range of Small Block and Big Block Chevrolet engines. It is compatible with:

• Small Block Chevy: 283, 305, 327, 350, and 400 cubic inch engines.
• Big Block Chevy: 396, 427, and 454 cubic inch engines.
• Camshafts: Fully compatible with both hydraulic and solid flat tappet camshafts.

The distributor utilizes an OE 0.491" diameter shaft. For vehicles equipped with a solid roller camshaft, a different drive gear will be required (not included).

Figure 3: Close-up view of the standard-type steel distributor gear.

3. Installation (Setup)

The JEGS HEI Distributor is designed for easy drop-in installation, typically requiring only a 1-wire hook-up for operation.

Wiring Recommendation:

When installing this HEI distributor in a vehicle that was not originally equipped with an HEI system, the use of JEGS Power & Tach Feed Wires (Part Number 555-10552) is recommended to ensure proper electrical connection and functionality.

Always ensure the vehicle's battery is disconnected before beginning any electrical or mechanical installation work. Consult a qualified automotive technician if you are unsure about any installation steps.

4. Operating Principles

The JEGS HEI Distributor integrates the ignition coil and control module into a single unit, simplifying the ignition system. Its 65,000 Volt coil generates a powerful spark, contributing to efficient fuel combustion and improved engine performance.

The adjustable vacuum and mechanical advance mechanisms work in conjunction to optimize ignition timing across various engine speeds and loads, enhancing both horsepower and fuel economy.

5. Maintenance

The JEGS HEI Distributor is engineered for durability and minimal maintenance. Key design features that contribute to its longevity include:

• Coated Weights: The internal weights are coated to resist corrosion, ensuring smooth and consistent advance operation over time.
• Welded Weight Pins: The weight pins are welded for enhanced durability, preventing loosening or failure under engine vibrations and stresses.
• CNC Aluminum Body: The robust aluminum housing provides protection for internal components and dissipates heat effectively.

Regular visual inspection of the distributor cap, rotor, and wiring for signs of wear or damage is recommended during routine engine maintenance.

6. Troubleshooting

While the JEGS HEI Distributor is designed for reliable performance, should you encounter any issues, consider the following general troubleshooting steps:

• No Spark/Weak Spark: Verify all electrical connections are secure, especially the 1-wire hook-up. Ensure adequate voltage supply to the distributor. Inspect the coil and module for any visible damage.
• Engine Misfire/Rough Idle: Check the condition of the spark plug wires and spark plugs. Confirm proper timing adjustment.
• Engine Cranks but Won't Start: Ensure the distributor is correctly seated and aligned with the oil pump drive. Verify power supply.

For complex issues or if you are unable to resolve a problem, it is recommended to consult a qualified automotive mechanic or contact JEGS customer support for assistance.

7. Specifications

8. Warranty and Support

For information regarding product warranty, returns, or technical support, please contact JEGS customer service directly. You can find contact details on the official JEGS website or through your point of purchase.

JEGS is committed to providing quality performance parts and support to its customers.