Classic vehicles, particularly models like the 1979 Scout II, often require specialized ignition components to maintain reliability and performance. The Accel 8140 coil and related ignition conversion kits, such as the Accel Points Eliminator Kit for General Motors (GM) applications, are frequently employed by enthusiasts and mechanics to upgrade or replace aging ignition systems. These components are often used in conjunction with aftermarket distributors like the Mallory Unilite, which offer optical trigger systems and vacuum advance features. However, users have reported issues such as intermittent ignition failure, coil overheating, and compatibility problems when integrating these parts with older vehicles.
This article examines the installation and troubleshooting of Accel ignition components based on user experiences and technical documentation from forums, manuals, and technical guides. It explores the role of coils, ballast resistors, and distributor compatibility in maintaining a stable ignition system and provides insights into potential pitfalls and solutions for common issues.
Accel Ignition Components and Their Roles
The Accel 8140 coil is a high-output ignition coil designed to provide consistent spark energy in both stock and modified engines. It is often used in conjunction with the Accel Points Eliminator Kit, which replaces mechanical points with an electronic ignition system. This setup eliminates the need for point gap adjustments and offers improved reliability. The kit typically includes a module, trigger, and installation instructions.
In the context of a 1979 Scout II, one user reported that after replacing a faulty coil with the Accel Super Stock coil, the vehicle experienced intermittent ignition failures. The user installed a Mallory Unilite distributor with an optical trigger system and a 1.5–1.8 ohm ballast resistor to regulate voltage. Despite these upgrades, the engine would randomly stall, with the last incident occurring shortly after a restart. This scenario suggests that while the Accel coil is a core component, other factors—such as resistor compatibility, distributor function, or wiring—may also contribute to ignition issues.
Installation and Configuration Considerations
When installing ignition conversion kits such as the Accel Points Eliminator, several factors must be carefully considered to ensure optimal performance:
Ballast Resistor Compatibility: Some users have reported that the inclusion of a ballast resistor may affect the performance of high-output coils. The resistor is designed to limit the current flowing to the coil, preventing overheating in older vehicles with 12-volt systems. However, if the resistor is not properly sized or wired, it may reduce the coil’s ability to generate a strong spark. In one case, a user questioned whether removing the resistor and switching to an MSD Blaster coil might improve performance.
Distributor Integration: The Mallory Unilite distributor, which uses an optical trigger system, requires precise installation and timing adjustments. This is particularly important in vehicles driven at high altitudes, where air density and fuel mixture can significantly affect engine performance. In one instance, a user in Wyoming had a local shop install the distributor, but due to a lack of personal experience with high-altitude tuning, the setup was left to professionals. This highlights the importance of proper installation when integrating new ignition systems into classic vehicles.
Plug Wire and Spark Plug Selection: The user in question upgraded to 8mm MSD plug wires but did not replace the spark plugs. While high-quality plug wires can improve voltage delivery, it is also important to ensure that the spark plugs are in good condition and properly gapped. In some cases, worn or improperly gapped plugs can prevent the ignition system from firing consistently.
Troubleshooting Common Issues
Intermittent ignition failures can be frustrating and difficult to diagnose. Based on the available data, several potential causes have been identified:
Coil Failure: One user reported that after replacing a faulty coil with an Accel Super Stock model, the vehicle ran fine for several months before experiencing a complete loss of spark. This suggests that while the coil is a durable component, it is not immune to failure. Factors such as voltage spikes, overheating, or improper grounding can all contribute to coil degradation.
Distributor Malfunction: The Mallory Unilite distributor, while reliable in many applications, has been reported to fail prematurely in some cases. One user asked whether it was common for the distributor to fail within a short period of use. Although no definitive data was provided, it is known that optical trigger systems can be sensitive to dirt, misalignment, or electrical interference.
Wiring and Grounding Issues: Proper wiring and grounding are essential for a stable ignition system. In one case, the user mentioned that they had not left the ignition key on for more than 30 seconds, ruling out the possibility of coil overheating due to prolonged cranking. However, a poor ground connection or damaged wiring could still prevent the coil from receiving consistent power.
Alternative Solutions and Recommendations
For users experiencing ignition issues with the Accel 8140 coil or related components, several alternative solutions may be worth considering:
Upgrade to a High-Performance Coil: Some users have suggested switching to an MSD Blaster coil, which is designed to handle higher voltage and current than standard coils. This could potentially eliminate the need for a ballast resistor and provide a more stable ignition system.
Verify Distributor Functionality: If the Mallory Unilite distributor is suspected to be the source of the problem, it may be worth testing the optical trigger system for proper alignment and functionality. This can be done by using a timing light or multimeter to check for consistent signal output.
Check for Electrical Shorts and Grounds: A thorough inspection of the ignition wiring and grounding points can help identify potential faults that may be contributing to the issue. This includes checking for damaged insulation, loose connections, or corrosion at the coil and distributor terminals.
Conclusion
The Accel 8140 coil and related ignition conversion kits are widely used in classic vehicle restoration and performance tuning. While these components offer improved reliability over mechanical ignition systems, they require careful installation and configuration to function optimally. Users have reported issues such as coil failure, distributor malfunction, and wiring problems, which can all contribute to intermittent ignition failures.
For those seeking to maintain or upgrade their classic vehicle’s ignition system, it is essential to ensure compatibility between all components and to follow proper installation procedures. Troubleshooting should begin with the most likely causes—such as coil failure or wiring issues—and progress to more complex diagnostics if necessary. By understanding the role of each component and following best practices, users can improve the reliability and performance of their ignition systems.