Ignition Contact Set Replacement Guide for the 1941-1947 GMC EC100
Keep your classic GMC's engine firing reliably with the right ignition points.
- Failing ignition points cause hard starting, rough running, and stalling in your EC100.
- For this classic truck, new aftermarket parts are the standard replacement; Standard Ignition is a reliable brand.
- Always replace the condenser at the same time as the ignition contact set for best results.
- This is a simple, low-cost DIY job that is critical for maintaining your truck's performance and reliability.
Understanding Your EC100's Ignition System
The 1941-1947 GMC EC100 uses a simple and reliable mechanical ignition system. Unlike modern cars with computers, your truck relies on an ignition contact set, or "points," to time the spark. These points are a wearable part, like brake pads, and need to be checked and replaced as part of a regular tune-up. Over time, the electrical contact surfaces can burn, pit, or wear down, causing poor engine performance. Replacing them is a key part of maintaining your classic truck's reliability.
Symptoms of Failing Ignition Points
When the ignition contact set starts to fail, your truck will give you clear signs. Because the points control the spark for all cylinders, the symptoms usually affect the entire engine. Look out for these common problems:
- Hard Starting or No Start: The most common sign is difficulty starting the engine. Worn or dirty points can't create the clean electrical break needed for a strong spark. You may find the engine cranks over but refuses to fire up.
- Rough Idle and Misfiring: If the points are pitted or misaligned, they can cause a weak or inconsistent spark. This leads to an engine that misfires, shakes, or idles unevenly.
- Engine Stalling: Worn points can fail to deliver a consistent spark at low speeds, causing the engine to stall when you come to a stop or at idle.
- Reduced Power and Hesitation: If your truck feels sluggish or hesitates when you press the gas pedal, it could be due to failing points. An inefficient spark means the engine isn't producing its full power.
Choosing the Right Aftermarket Part
For a vehicle from the 1940s, finding original "new old stock" (NOS) parts is very difficult and expensive. New aftermarket parts are the most practical and reliable choice for keeping your EC100 on the road. The quality of modern aftermarket ignition components is generally very good.
Standard Ignition: Standard Motor Products (SMP) is a well-known and respected brand for ignition components, especially for classic American vehicles. Forum users and mechanics often consider Standard a go-to choice when OEM parts are unavailable. Their parts are designed to meet original specifications and are known for reliability. For your EC100, a Standard Ignition contact set is a dependable option that will restore original performance.
Aftermarket Cost for 1941-1947 GMC EC100
| Part | Brand | Price Range |
|---|---|---|
| Ignition Contact Set | Standard Ignition | $21.44 |
Pro Tip: Replace the Condenser Too
The condenser is a small capacitor that works with the points to prevent them from arcing and burning out prematurely. It's inexpensive and located right next to the points in the distributor. It is always recommended to replace the condenser at the same time you replace the points.
Frequently Asked Questions (FAQ)
How often should I replace my ignition points?
For a classic truck that is driven regularly, ignition points should be inspected during every tune-up and typically replaced every 10,000 to 12,000 miles. Since they are inexpensive, it's good practice to replace them whenever you are servicing the distributor.
Is replacing ignition points a difficult job?
No, this is a very DIY-friendly job for someone with basic mechanical skills. It requires simple hand tools like a screwdriver and a feeler gauge to set the correct gap. The entire process usually takes less than an hour. There are many general video guides online for replacing points in classic GM distributors.
What is the correct point gap for my GMC truck?
The correct point gap is essential for proper engine timing. For the 6-cylinder engines in these trucks, the gap is typically set around .019 inches for new points. Always verify the correct specification for your specific engine and use a feeler gauge to set the gap when the rubbing block on the points is on the highest spot of the distributor cam lobe.
Should I upgrade to an electronic ignition?
Many owners of classic trucks choose to replace the points and condenser with an electronic ignition conversion kit. These kits eliminate the need for regular adjustments and can provide a more consistent spark. However, a well-maintained original points system is very reliable. The choice depends on whether you prefer modern convenience or maintaining the truck's original character.
Technical Specifications
System Type: Breaker Points Ignition. Point Gap (New): Approx. 0.019 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.