A Guide to the Ignition Contact Set for the 1952-1958 GMC PM252
Keep your classic GMC's engine firing reliably with the right set of ignition points.
- The ignition contact set, or points, is a normal wear item that requires periodic replacement.
- Always replace the ignition condenser at the same time as the points for a complete and lasting repair.
- Properly setting the point gap with a feeler gauge, and ideally checking it with a dwell meter, is critical for engine performance.
- High-quality aftermarket brands like Standard Ignition are the industry standard for these vintage vehicles, as new OEM parts are no longer made.
Symptoms of a Failing Ignition Contact Set
Ignition points are a wear item, meaning they need to be replaced as part of regular maintenance. The constant opening and closing, along with the electrical arc, causes the contact surfaces to pit and burn over time. The small rubbing block that rides on the distributor cam also wears down, which changes the adjustment. When your points are failing, your truck will let you know.
Common Symptoms of Bad Points:
- Hard Starting or No-Start: The engine cranks over but won't fire up. This is often because the points are too worn or corroded to signal the coil to create a spark.
- Engine Misfires: The engine sputters, shakes, or runs unevenly, especially when you try to accelerate. This is caused by an inconsistent or weak spark.
- Rough Idle and Stalling: The engine may stall when you come to a stop or idle roughly because the spark is too weak to keep it running at low speeds.
- Backfiring: A pop or bang from the exhaust can occur when unburned fuel ignites in the hot exhaust pipe, a common result of misfires from bad points.
Choosing the Right Aftermarket Ignition Contact Set
For a vehicle from the 1950s, new original equipment (OEM) parts from GMC are no longer produced. The market is served by high-quality aftermarket manufacturers who specialize in vintage ignition components. For your PM252, this is not a compromise; it is the standard and most reliable way to get new parts.
Standard Ignition is a widely available and respected brand that has been making ignition parts for decades. They are a trusted choice for classic truck owners. Their parts are known to be reliable and are manufactured to meet or exceed the original specifications. When buying a new set of points, it is highly recommended to also replace the ignition condenser. The two parts work together, and a new condenser is crucial for protecting the new points from premature failure.
Cost of a New Ignition Contact Set (1952-1958 GMC PM252)
| Part or Service | Estimated Cost |
|---|---|
| New Aftermarket Ignition Contact Set | $21.44 - $31.16 |
| New OEM | Not Available |
| Shop Labor | $90 - $180 |
Pro Tip: Check for Distributor Wobble
If you replace your points and still experience a persistent misfire, check your distributor shaft for side-to-side movement. A worn distributor bushing can cause the point gap to change unpredictably as the engine runs, mimicking the symptoms of bad points.
Frequently Asked Questions
Can I replace the ignition points myself?
Yes, this is a very common DIY job for owners of classic vehicles. It requires basic hand tools, a feeler gauge, and a screwdriver. The key to success is setting the correct "gap" on the points when they are fully open. For best results, a dwell meter should be used to fine-tune the adjustment.
How often do I need to replace my ignition points?
As a general maintenance item, points should be inspected at every major tune-up and typically replaced every 10,000-15,000 miles. Because they are inexpensive, it's good practice to replace them if they show any visible pitting, burning, or wear on the rubbing block.
What is the difference between point "gap" and "dwell"?
The "gap" is the physical distance between the contacts when the points are fully open, set with a feeler gauge. "Dwell" is the amount of time (measured in degrees of distributor rotation) that the points remain closed. Dwell is the more accurate measurement and is checked with the engine running using a dwell meter. Setting the gap is a way to get the dwell in the correct range.
Are there any recalls for the ignition system on my GMC PM252?
No, there are no active recalls or technical service bulletins (TSBs) from the NHTSA for the ignition system on this vehicle. The formal recall systems used today were not in place for vehicles of this era.
Technical Specifications
Compatibility depends on the specific distributor used in the GMC 6-cylinder engine of the era. Always verify the part matches your vehicle's distributor.
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.