Ignition Contact Set Guide for the 1947 GMC EC280
Keep your classic GMC's engine firing correctly with the right ignition points.
- The ignition contact set (points) is a routine maintenance part on the 1947 GMC EC280 that is critical for engine operation.
- Common signs of failure include no-start, rough idle, stalling, and loss of power.
- Standard Ignition is a reliable aftermarket brand for this component.
- Always replace the ignition condenser at the same time as the points for best results.
Understanding the Ignition System in Your Classic Truck
For owners of a 1947 GMC EC280, the ignition contact set is a key part of what makes the engine run. These trucks, often equipped with a 228 cubic inch inline-six engine, rely on this simple but effective mechanical ignition system. Unlike modern cars with electronic ignition, this system needs regular checks and adjustments. The points wear down from the constant mechanical rubbing and the electrical current that passes through them, which makes them a routine replacement item.
Symptoms of a Failing Ignition Contact Set
When the points start to fail, your truck's performance will suffer. Recognizing the signs can prevent you from getting stranded.
- Hard Starting or No Start: This is the most common symptom. Worn, pitted, or incorrectly gapped points can't make the proper electrical connection to trigger a strong spark. This can cause the engine to turn over but not fire up.
- Rough Idle and Misfiring: As the small rubbing block on the points wears down, the timing of the spark changes. This leads to an inconsistent spark, causing the engine to shake, run rough, and misfire.
- Engine Backfiring: If the points are not gapped correctly, the spark can happen at the wrong time. This may cause loud backfires from the exhaust or carburetor.
- Stalling at Low Speeds: A weak or inconsistent spark at low engine speeds, like when you're idling at a stop, can cause the engine to stall unexpectedly.
- Reduced Power: If the spark is weak, the fuel in the cylinders won't burn completely. This results in poor acceleration and a noticeable loss of engine power.
OEM vs. Aftermarket Parts
For a 1947 vehicle, new original equipment manufacturer (OEM) parts are no longer available. All new replacement parts are considered aftermarket. The key is to choose a reputable brand known for making quality components for vintage vehicles. Standard Ignition is a well-known brand in the aftermarket and its "Blue Streak" line is often considered a premium quality option for older ignition systems.
Choosing the Right Aftermarket Ignition Contact Set
Since only one brand option is readily available for your specific model, the choice is straightforward. Standard Ignition is a long-standing manufacturer that produces parts designed to meet or exceed original specifications. For vintage applications like the GMC EC280, their parts are a reliable choice for keeping your truck on the road.
Pro Tip: It is highly recommended to replace the ignition condenser at the same time as the points. The condenser absorbs excess voltage to prevent the points from burning out prematurely. A failing condenser can cause similar symptoms to bad points.
Estimated Replacement Costs
| Part Type | Estimated Cost |
|---|---|
| New Aftermarket Ignition Contact Set | $21.44 |
| Shop Labor | $100 - $200 |
| Total Estimated Cost | $121 - $221 |
Frequently Asked Questions (FAQ)
How often should I replace the ignition points?
For a vehicle like the 1947 GMC EC280, ignition points should be inspected during every tune-up. A general replacement interval is every 10,000 to 12,000 miles, or if you notice any of the common failure symptoms.
What is the correct gap for the points?
The point gap is critical. For similar 6-cylinder GM engines of this era, the gap is typically set to .018" for new points. This is measured with a feeler gauge when the rubbing block is on the highest point of the distributor cam. An incorrect gap will affect engine timing and performance.
Can I replace the ignition contact set myself?
Yes, this is a common DIY job for classic truck owners. It requires basic hand tools, a feeler gauge, and an understanding of how to access the distributor and set the point gap. It is considered a beginner-to-intermediate level task.
What other parts should I inspect when replacing the points?
When you replace the points, it's a good time to also replace the condenser. You should also inspect the distributor cap and rotor for any cracks, carbon tracking, or corrosion and replace them if needed.
Technical Specifications
Mechanical breaker points located inside the distributor. Requires a specific point gap setting, typically .018 inches for new points on similar era GM 6-cylinder engines.
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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.