Ignition Coil Guide for the 1946 GMC EC350 Truck
Keep your classic GMC's 6-volt system running strong with the right ignition coil.
- The 1946 GMC EC350 requires a 6-volt ignition coil for its distributor-based system.
- A common failure symptom is the engine running poorly or stalling after it warms up.
- Replacing the coil is an affordable and straightforward DIY job for most owners.
- Modern aftermarket brands like Standard Ignition are a reliable choice for this vintage application.
Is Your GMC's Ignition Coil Failing?
An ignition coil on a vintage truck like the 1946 GMC EC350 can fail gradually. A common sign of a failing 6-volt coil is when the engine runs fine when it's cold but starts to misfire, stumble, or run poorly after it warms up. This happens because heat increases resistance in the coil's internal windings, causing its performance to drop. You might also notice the truck is hard to start, idles roughly, backfires, or has less power than usual. In some cases, a completely failed coil will produce no spark at all, preventing the engine from starting.
No-Start Condition
If your truck cranks but won't start, a bad ignition coil is a likely suspect. Along with the coil itself, be sure to check the simple parts connected to it, like the condenser and the points inside the distributor, as they can also cause a no-spark issue.
Choosing an Aftermarket Ignition Coil
For a 1946 GMC, finding a "new old stock" (NOS) OEM part is nearly impossible and often not practical. Modern aftermarket coils are designed to be reliable replacements. The key is to ensure you are purchasing a 6-volt coil, as installing a 12-volt coil will result in a very weak or no spark.
Brand Spotlight: Standard Ignition
Standard Ignition is a well-known aftermarket brand that produces a wide range of ignition components. Their products are generally considered a reliable, quality replacement for original parts. For a vintage application like the EC350, a Standard Ignition coil is engineered to meet the demands of an older engine, providing consistent spark energy. They are a common and trusted choice for keeping these classic trucks on the road.
Pro Tip: Check for Correct Polarity
When installing your new coil, make sure the primary wires are connected correctly. On a 6-volt system, reversing the polarity can reduce the coil's output by about 20%, leading to poor performance under load or at higher RPMs.
Cost of a New Ignition Coil
Replacing the ignition coil on a 1946 GMC EC350 is one of the more affordable repairs. The part itself is not expensive, and labor is straightforward for a mechanic familiar with vintage vehicles.
| Part Type | Estimated Cost |
|---|---|
| New Aftermarket (e.g., Standard Ignition) | $32 - $39 |
| Shop Labor | $50 - $100 |
Frequently Asked Questions
Do I need a special coil for my 1946 GMC?
You don't need a rare or vehicle-specific model, but you absolutely MUST use a 6-volt ignition coil that is designed for a conventional distributor-based ignition system. Using a 12-volt coil will not work correctly.
My coil gets hot. Is that normal?
Ignition coils naturally generate some heat during operation. However, if the coil becomes too hot to touch, it could be a sign of an internal failure or a problem with another part of the ignition system, like incorrect wiring or a faulty ignition switch. Coils often fail when they get hot, leading to the engine cutting out and only restarting after it cools down.
What other parts should I inspect when replacing the coil?
It's a good practice to inspect the other main components of the ignition system. Check the distributor cap and rotor for cracks or carbon buildup, inspect the ignition points for wear, and consider replacing the condenser, as it works directly with the coil. Also, check the condition of the spark plug wires.
Can I replace the ignition coil myself?
Yes, this is a very feasible DIY job for most owners. It typically involves disconnecting the battery, removing two low-voltage wires and the main high-tension wire to the distributor, and unbolting the coil from its bracket. The process is simple and requires basic hand tools.
Technical Specifications
Voltage: 6 Volt Ignition Type: Conventional Canister Coil System: Distributor-based ignition
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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.