1938 GMC T155 Ignition Contact Set (Points) Replacement Guide
Keep your classic GMC's inline-6 engine running smoothly with a reliable new ignition contact set.
- The ignition contact set (points) is a normal wear item that requires replacement every 6,000-12,000 miles.
- Symptoms of failure include hard starting, rough idle, misfires, and power loss.
- For a 1938 vehicle, a quality aftermarket brand like Standard Ignition is the best and most practical choice.
- Always replace the condenser at the same time as the points for maximum reliability.
Understanding the Ignition Contact Set in Your 1938 T155
On vintage trucks like the 1938 GMC T155, the ignition system is a straightforward mechanical setup. Unlike modern cars with computers, your truck relies on an ignition contact set, or 'points,' to time the spark. These points are a set of electrical contacts that act as a switch. They are a normal wear-and-tear item because the rubbing block that rides on the distributor cam wears down, and the electrical contacts can become pitted or burned over time. Regular inspection and replacement are key to keeping your classic truck reliable.
Choosing the Right Aftermarket Ignition Contact Set
For a vehicle from 1938, finding New Old Stock (NOS) OEM parts is extremely rare and often impractical. Aftermarket parts are the go-to solution for keeping these trucks on the road. The quality of modern aftermarket points can vary, but reputable brands provide reliable service.
- Standard Ignition: Standard Motor Products (SMP), the parent company of Standard Ignition, has a long-standing reputation for producing quality ignition components for American vehicles. For a GMC T155, a Standard Ignition contact set is a reliable and widely available choice that meets or exceeds the original design's performance.
Pro Tip: Replace the Condenser
The condenser is a small capacitor that works with the points to prevent them from arcing and burning out prematurely. It is highly recommended to replace the condenser every time you replace the ignition contact set. They are often sold together in a kit.
Anticipated Replacement Costs
Replacing the ignition points is a common tune-up job on a classic truck. The parts are inexpensive, and the labor is simple for anyone familiar with vintage ignition systems.
| Part/Service | Estimated Cost | Notes |
|---|---|---|
| New Aftermarket Ignition Contact Set | $26.77 - $27.65 | This is the typical price range for a quality aftermarket brand like Standard Ignition. |
| New OEM (NOS) | Not Generally Available | Original 1938 parts are collector's items and not practical for regular use. |
| Shop Labor | $90 - $150 | Estimated 1 hour of labor. Rates vary by shop. |
Known Issues for This Part
No specific recalls or Technical Service Bulletins (TSBs) from GMC or the NHTSA exist for the ignition contact set on a 1938 GMC T155, which is normal for a vehicle of this era. The primary 'issue' is the standard wear and tear these components experience. The rubbing block wears down, and the contact surfaces pit from the electrical arc, requiring replacement roughly every 6,000 to 12,000 miles as part of a regular tune-up.
Frequently Asked Questions (FAQ)
What does 'gapping the points' mean?
Gapping the points refers to setting the correct maximum distance between the two electrical contacts when they are opened by the distributor cam. This gap is measured with a feeler gauge and is critical for correct ignition timing and coil saturation. An incorrect gap can lead to a weak spark, poor performance, or engine overheating.
Can I upgrade to an electronic ignition?
Yes, many owners of classic vehicles choose to replace the points and condenser system with a modern electronic ignition conversion kit. These kits eliminate the need for regular point replacement and can offer more consistent performance. However, a properly maintained original-style points system is very reliable. Some owners prefer the originality and ease of roadside repair that points offer.
Why did my engine suddenly stop running?
While several issues can cause this, a failed ignition contact set or condenser is a common culprit in these systems. The small wire leading to the points can break, or the condenser can fail suddenly, which will immediately kill the spark and shut off the engine.
Is an ignition contact set the same as an ignition module?
No. An ignition contact set (points) is a mechanical switch used in older vehicles. An ignition control module is an electronic component that replaced points in later ignition systems. Your 1938 GMC T155 uses a mechanical contact set, not an electronic module.
Technical Specifications
Mechanical ignition contact set for inline 6-cylinder engine with distributor. Requires manual gap setting.
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.