Ignition Contact Set Replacement for the 1947 GMC EC251
Understanding the heart of your classic truck's ignition system is key to keeping it on the road.
- Failing ignition points on your 1947 GMC EC251 will cause hard starting, rough running, stalling, and power loss.
- Since OEM parts are unavailable, a new aftermarket set from a reputable brand like Standard Ignition is the best and only option.
- Always replace the ignition condenser at the same time as the points to ensure longevity and prevent premature failure.
- Setting the correct point gap (typically .018" for new points) with a feeler gauge is critical for proper engine function.
Understanding the Ignition Contact Set in Your Classic Truck
For owners of a vintage 1947 GMC EC251, the ignition contact set, or points, is a core part of what makes the engine run. Unlike modern cars with electronic ignition, this system is fully mechanical and electrical, requiring periodic maintenance. The points wear down from the constant opening and closing, as well as the small electrical arc that occurs each time. Worn or incorrectly adjusted points can cause a variety of engine problems, from poor performance to leaving you stranded.
Symptoms of a Failing Ignition Contact Set
When your ignition points start to fail, the signs are usually clear. Recognizing them early can prevent a complete no-start situation. Common symptoms include:
- Difficulty Starting: This is often the first sign. Worn or pitted points can't make proper electrical contact, leading to a weak or inconsistent spark. Your engine may turn over but struggle to fire up.
- Engine Misfires and Rough Running: If the points are dirty, pitted, or not gapped correctly, the spark sent to the plugs can be inconsistent. This results in the engine running rough, shaking, or feeling unbalanced, especially at idle.
- Stalling: Worn points can fail to deliver a consistent spark at low RPMs, causing the engine to stall at idle or when you come to a stop.
- Backfiring: Improperly timed sparks due to worn points can cause the engine to backfire through the carburetor or exhaust.
- Loss of Power: If the points can't deliver a strong, consistent spark, the engine won't produce full power, leading to sluggish acceleration.
Choosing the Right Aftermarket Part
Original equipment (OEM) ignition points for a 1947 GMC truck have not been produced for many decades. Your only realistic option is a new aftermarket part. Fortunately, reputable brands have been making quality replacement parts for these classic trucks for years.
Brand Assessment: Standard Ignition
The only brand listed in our inventory for your truck is Standard Ignition. This is a well-established brand in the aftermarket and is generally considered to produce quality parts for vintage American vehicles. Forum discussions among classic car owners often mention Standard Ignition as a reliable choice, sometimes even being the manufacturer for other store brands. For a stock restoration or a reliable driver, a new set of points from Standard Ignition is a dependable choice.
Pro Tip: Replace the Condenser Too
The ignition condenser is a small capacitor that works with the points to prevent them from arcing and burning out prematurely. It's inexpensive and highly recommended to replace the condenser every time you replace the ignition points. Many ignition point sets come with a new condenser included.
Replacement Cost for a 1947 GMC EC251
Replacing the ignition contact set is one of the more affordable maintenance jobs on a classic truck. The part itself is inexpensive, and the labor is straightforward for a mechanic familiar with vintage ignition systems.
| Part/Service | Estimated Cost |
|---|---|
| New Aftermarket Ignition Contact Set | $21.44 |
| Shop Labor | $70 - $120 |
| Total Estimated Cost | $91 - $141 |
Cost estimates are based on the provided inventory price and national labor rate averages. Actual costs may vary based on your location and chosen repair shop.
Frequently Asked Questions (FAQ)
How often should I replace my ignition points?
As a general maintenance rule, ignition points should be inspected at every tune-up and replaced approximately every 10,000 to 12,000 miles. Because they are a wear item, carrying a spare set in your glove box is a wise precaution for any classic truck owner.
What is the correct point gap for my truck?
The point gap is critical for performance. For a 1947 GM 6-cylinder engine, the gap for new points is typically set to .018 inches. This measurement is taken when the rubbing block on the points is resting on the highest point of the distributor cam lobe. A feeler gauge is required for this adjustment.
What is 'dwell' and do I need to set it?
Dwell is the amount of time, measured in degrees of distributor rotation, that the points remain closed. Setting the point gap correctly will typically result in the correct dwell angle. For a more precise tune-up, a dwell meter can be used to achieve the exact specification, which is usually between 28-32 degrees for these 6-cylinder engines.
Can I just clean my old points?
If the points are only slightly oxidized, they can be cleaned with a points file or a piece of fine-grit sandpaper as a temporary fix to get you home. However, if the points are pitted, burned, or worn, they must be replaced for reliable operation.
Are there any recalls or technical bulletins for the ignition system?
No. Formal recalls and Technical Service Bulletins (TSBs) as we know them today did not exist for vehicles manufactured in 1947. Any known issues are based on common knowledge and repair practices for vehicles of this era.
Technical Specifications
Point Gap (New): .018 inches
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.