Ignition Contact Set Guide for 1935-1937 GMC T16L Trucks
Keep your classic GMC's engine running smoothly with the right set of ignition points.
- The ignition contact set (points) is a regular maintenance item on the 1935-1937 GMC T16L that requires periodic replacement.
- Always replace the condenser at the same time as the points to ensure longevity and prevent premature failure of the new points.
- For reliability, choose a premium aftermarket brand like Standard Ignition's Blue Streak line if available.
- Setting the correct point gap with a feeler gauge is critical for proper engine performance and starting.
Understanding the Ignition Contact Set in Your Vintage GMC
The ignition contact set, or points, is a fundamental part of your 1935-1937 GMC T16L's ignition system. Unlike modern cars with computer-controlled electronic ignition, your truck relies on this simple, mechanical switch to time the spark that makes the engine run. The points consist of two small tungsten contacts that are opened and closed by a rotating cam inside the distributor. Over time, the rubbing block that rides on the cam wears down, and the electrical contacts can burn or pit, requiring periodic adjustment or replacement.
Symptoms of a Failing Ignition Contact Set
When your ignition points start to fail, the engine's performance will suffer. The symptoms can start small but will get worse, potentially leaving you stranded.
- Rough Idle: The engine may shake or run unevenly when stopped because of inconsistent spark.
- Misfiring or Stumbling: During acceleration, the truck may hesitate, pop, or buck as the worn points fail to deliver a timed spark.
- Poor Engine Performance: You might feel a general lack of power and reduced fuel economy because the spark timing is no longer accurate.
- Backfiring: Incorrect timing can cause fuel to ignite in the exhaust, leading to loud backfires.
- Engine Won't Start: If the points are completely burned, pitted, or stuck closed, they cannot trigger the ignition coil to create a spark. This will result in a no-start condition.
Choosing the Right Aftermarket Part
For a vintage truck like the T16L, finding a "new OEM" part from General Motors is not a realistic option. The market today consists entirely of aftermarket parts. Fortunately, the technology is simple, and reputable aftermarket brands produce reliable replacements.
Brand Quality: Standard Ignition
Standard Motor Products (SMP), often sold as Standard Ignition, is a well-known manufacturer of ignition components. They have a long history and are generally considered a reliable choice for classic vehicles. For critical parts like ignition points, it's worth seeking out their premium line, often called "Blue Streak." These premium versions are built with better materials, such as a more durable rubbing block and higher quality contacts, which leads to a longer service life. Given the small price difference, opting for a premium set is a smart investment in reliability.
Pro Tip: Replace the Condenser Too
It is highly recommended to replace the ignition condenser every time you replace the contact set. The condenser's job is to absorb excess voltage, which prevents the points from arcing and burning out prematurely. A weak or failing condenser will cause a new set of points to fail very quickly. Most quality contact sets are sold as a kit that includes a new condenser.
Cost Comparison for a New Ignition Contact Set
| Part Type | Estimated Cost | Notes |
|---|---|---|
| New Aftermarket | $21.44 - $43.97 | This is the most common and practical option. Price varies by brand and quality (e.g., standard vs. premium). |
| New OEM | Not Available | Original parts from the 1930s are no longer manufactured. |
| Used OEM (NOS) | $15+ | New Old Stock parts may be found, but their age can make them unreliable. Not recommended for a wear item. |
| Shop Labor | $100 - $150 | Expect about one hour of labor at a shop familiar with vintage vehicles. |
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 1935-1937 GMC T16L. The modern systems for tracking and issuing these notices were not in place during the vehicle's production era. Searches for recalls on modern GM ignition systems are not relevant to this vehicle.
Frequently Asked Questions
How often should I replace my ignition points?
For a vehicle that is driven regularly, ignition points are a routine maintenance item that should be inspected and adjusted every 6,000 to 8,000 miles and typically replaced every 12,000 to 15,000 miles. However, if you only drive your T16L occasionally, it's good practice to inspect them annually.
What tools do I need to replace the ignition points?
You will need basic hand tools like a screwdriver and wrenches to remove the distributor cap. The most important special tool is a feeler gauge to set the point gap correctly. Some mechanics also use a dwell meter for more precise adjustment.
What is the correct point gap for my GMC T16L?
The correct point gap is crucial for proper engine timing. For the inline-six engines of this era, a common gap setting is around .018 to .020 inches, but you should always consult a service manual for your specific engine if possible. Setting the gap correctly ensures the coil has enough time to charge, resulting in a strong spark.
Can I upgrade my T16L to electronic ignition?
Yes, converting to an electronic ignition is a very common and popular upgrade for classic vehicles. Kits, such as those from Pertronix, are designed to replace the points and condenser inside the original distributor. This eliminates the need for regular point adjustment and can provide a more reliable and consistent spark, improving starting and overall performance.
Technical Specifications
OEM Part Numbers: 1855520
Mechanical ignition contact set with tungsten points and a rubbing block, designed for use in the original Delco-Remy distributor. Often includes a matching condenser.
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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.