Ignition Contact Set Guide for the 1955-1959 GMC 100
Keep your classic GMC 100's ignition system reliable with the right set of points.
- The ignition contact set, or points, is a critical tune-up part for your GMC 100 that requires regular replacement.
- Symptoms of failure include rough idle, misfiring, and no-start conditions.
- Brand quality is very important. Standard Ignition (Blue Streak) is a highly recommended aftermarket brand for reliability.
- Always replace the condenser at the same time as the points to prevent premature failure.
Symptoms of a Failing Ignition Contact Set
Ignition points wear out over time. The constant opening and closing causes the contact surfaces to pit and burn, and the rubbing block that rides on the distributor cam wears down. When this happens, you'll notice problems with how your truck runs.
- Rough Idle: The engine may shake or run unevenly when stopped.
- Misfiring or Stumbling: During acceleration, the truck may hesitate, pop, or buck.
- Poor Engine Performance: You might feel a general lack of power because the spark timing is no longer accurate.
- Engine Won't Start: If the points are completely burned, stuck closed, or not opening correctly, they can't create a spark, and the engine will not start.
Choosing the Right Aftermarket Part
For a vintage truck like the 1955-1959 GMC 100, original equipment (OEM) parts from GM are no longer produced. The market consists entirely of aftermarket parts. However, quality varies significantly among brands.
Brand Quality Tiers
| Tier | Brand(s) | Our Assessment |
|---|---|---|
| Premium Aftermarket | Standard Ignition (Blue Streak) | Standard Ignition, and specifically their Blue Streak line, has a long-standing reputation for being a top-quality choice for ignition components. Forum members and mechanics often recommend this brand for its reliability, which is crucial given that the quality of many modern points and condensers can be inconsistent. |
| Standard Aftermarket | Other store brands | While other brands are available, there is a general consensus in the classic vehicle community that the quality of ignition points has declined over the years. Cheaper, unbranded points may wear out faster or be difficult to set correctly, leading to poor performance sooner. |
Pro Tip: It is highly recommended to replace the ignition condenser at the same time as the contact set. The condenser absorbs excess voltage to prevent the points from arcing and burning out prematurely. A failing condenser can cause new points to fail very quickly.
Recalls and Technical Service Bulletins (TSBs)
There are no NHTSA recalls or manufacturer Technical Service Bulletins (TSBs) related to the ignition contact set for the 1955-1959 GMC 100. This is expected for a vehicle of this era, as the modern recall and TSB systems were not in place.
Frequently Asked Questions (FAQ)
What are ignition "points"?
"Points" is the common name for the ignition contact set. They are a mechanical switch inside the distributor that triggers the spark from the ignition coil. This is an older technology that requires regular maintenance, unlike modern electronic ignition systems.
How often should I replace my ignition points?
As a standard tune-up item, points were typically replaced every 10,000 to 15,000 miles. Given the variable quality of modern parts, it's a good idea to inspect them annually for pitting, burning, or wear on the rubbing block.
What is a "condenser" and why should I replace it?
The condenser is a small capacitor connected to the points. It prevents a large arc of electricity from jumping between the contacts as they open. This protects the points from burning up quickly. A new condenser is cheap insurance to make your new points last. Many owners report that new condensers can be unreliable, so buying a quality brand is important.
Can I upgrade to electronic ignition?
Yes, many owners of classic trucks choose to replace the original points and condenser system with an electronic ignition conversion kit. These kits eliminate the need for regular point adjustments and can provide a more consistent spark. However, a properly functioning points system is very reliable, and many owners prefer to keep the original setup.
Technical Specifications
The most critical specification is the point gap, which is set with a feeler gauge during installation. This gap determines the 'dwell angle,' which is the amount of time the points remain closed. Always refer to your vehicle's service manual for the correct point gap specification.
We Have This Part in Stock
The information in this article is provided for general reference and educational purposes only. Vehicle specifications, procedures, and part compatibility can vary by production date, trim level, and region. Always consult your vehicle's factory service manual and verify part numbers before purchasing or performing repairs. Safety-critical components such as airbags, seat belts, and braking systems should be installed by a qualified professional.