A Guide to Spark Plugs for the 1933 Pierce-Arrow Model 1247
Ensure your classic V-12 engine runs with the power and smoothness it was designed for by choosing the correct spark plugs.
- The recommended modern replacement is the Champion J11C spark plug.
- You must purchase a full set of 12 plugs for the V-12 engine.
- Verify the spark plug gap is set to .025 inches before installation.
- No modern recalls or TSBs exist for this classic vehicle.
Symptoms of Failing Spark Plugs
Even in a robust V-12 engine, failing spark plugs will make their presence known. Because there are twelve cylinders, a single fouled plug might be less obvious than in a smaller engine, but the symptoms will still appear. Signs that your spark plugs may need replacement include:
- Rough Idling: The engine may sound uneven or cause vibrations throughout the car when stopped.
- Engine Misfires: You might feel a hesitation or stumble from the engine, especially under acceleration. This happens when a cylinder fails to fire correctly.
- Hard Starts: Worn plugs can make it difficult for the engine to start, requiring longer cranking times.
- Poor Acceleration: If the car feels sluggish or less responsive than usual, weak or inconsistent sparks could be the cause.
- Reduced Fuel Economy: Inefficient combustion from bad plugs means you'll be making more frequent trips to the gas station.
A Note on Engine Codes
Your 1933 Pierce-Arrow was built long before the advent of On-Board Diagnostics (OBD) and "Check Engine" lights. Therefore, there are no diagnostic trouble codes (like P0300 for a misfire) associated with spark plug failure on this vehicle.
Choosing the Right Aftermarket Spark Plug
For a vehicle from 1933, the concept of "OEM" parts refers to New Old Stock (NOS), which is extremely rare and often prohibitively expensive. The standard and accepted practice for vintage vehicles like the Model 1247 is to use a high-quality, modern aftermarket equivalent. Champion has been a leading spark plug manufacturer since 1907 and is a period-appropriate and reliable choice for these engines.
Based on vendor data, the recommended modern replacement is the Champion J11C. It is a non-resistor type plug suitable for the original ignition system. When purchasing, remember you will need a full set of twelve plugs.
Check the Gap
While modern plugs often come pre-gapped, it is critical to verify the gap before installation. The recommended spark plug gap for a 1933 Pierce-Arrow Model 1247 using a modern plug is .025 inches. Using the correct gap ensures the spark is strong enough to ignite the fuel mixture efficiently.
Cost to Replace Spark Plugs
The total cost will depend on whether you perform the work yourself or hire a specialist in classic cars. Remember to budget for a full set of 12 plugs.
| Part Type | Price Range (Per Plug) | Total Parts Cost (12 Plugs) |
|---|---|---|
| New Aftermarket (Champion) | $3.70 - $4.69 | $44.40 - $56.28 |
Frequently Asked Questions
Are there any recalls or technical service bulletins (TSBs) for the spark plugs?
No. Official recalls and TSBs from manufacturers or agencies like the NHTSA are a modern practice. No such bulletins exist for a 1933 vehicle.
Is it difficult to replace the spark plugs myself?
For someone with mechanical experience, replacing the spark plugs is a manageable task. The main challenges are the number of plugs (12) and potentially limited access depending on engine bay configuration. It's important to have the correct spark plug socket and to avoid over-tightening the new plugs in the engine's aluminum heads.
Why is the spark plug gap so important?
The gap is the distance the electricity has to jump to create a spark. A gap that is too small can create a weak spark, while a gap that is too large may prevent a spark from firing at all, especially under load. The recommended .025" gap is designed to provide a strong, consistent spark with the vehicle's original ignition system.
Should I use resistor or non-resistor spark plugs?
The original system was designed for non-resistor plugs. The recommended Champion J11C is a non-resistor plug. Using resistor plugs can sometimes lead to a weaker spark in ignition systems not designed for them.
Technical Specifications
Recommended Aftermarket Part: Champion J11C Type: Non-Resistor Quantity Required: 12 Recommended Gap: .025 inches
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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.