Essential Spark Plug Guide for the 1940 Chrysler C26
Keep your classic Chrysler's engine running smoothly with the right set of new spark plugs.
- Use only standard copper-core spark plugs from a reputable brand like Champion, which was an original supplier.
- Avoid modern platinum or iridium plugs, as they are not compatible with the 1940 Chrysler's ignition system.
- Always check and set the spark plug gap before installation; a common setting is between .025" and .035".
- Replacement is a simple DIY task; change one plug at a time to ensure the firing order remains correct.
Choosing the Right Spark Plug for a Classic
For a vintage vehicle like the 1940 Chrysler C26, selecting a spark plug is about choosing the correct, proven technology. The distinction between "OEM" and "aftermarket" is less important than using a part that matches the original design. Champion was a common original equipment supplier for Chrysler in this era, so a new Champion plug is an excellent choice for maintaining authenticity and performance.
Stick with Copper Plugs
Your C26's ignition system was designed for standard copper-core spark plugs. It is best to avoid modern platinum or iridium plugs. These plugs require a higher-voltage ignition system than what vintage cars have. Using them in your Chrysler can lead to weak spark, fouling, and poor performance.
Recognizing a Failing Spark Plug
Worn spark plugs can cause noticeable problems. Because these classic engines are mechanically simple, performance issues often point to basic tune-up items like plugs. Look for these signs:
- Rough Idle: The engine may shake or sputter when the car is stopped.
- Engine Misfires: You might feel a stumble or hear a popping sound from the engine, especially under load.
- Hard Starting: A weak spark makes it difficult for the engine to fire up.
- Poor Acceleration: The car may feel sluggish or hesitate when you press the gas pedal.
- Reduced Fuel Economy: Inefficient combustion from a weak spark forces the engine to use more fuel.
You can also inspect your old spark plugs for clues about engine health. A plug with soft, black, sooty deposits indicates the engine is running too rich. Oily deposits can point to more significant engine wear, like worn piston rings or valve guides.
Aftermarket Spark Plug Cost for 1940 Chrysler C26
| Part | Our Price Range | Estimated Shop Labor |
|---|---|---|
| Spark Plug (Single) | $3.70 - $4.69 | $50 - $100 |
| Spark Plugs (Set of 8) | $29.60 - $37.52 |
Known Issues
No recalls or Technical Service Bulletins (TSBs) related to spark plugs are on file for the 1940 Chrysler C26. Modern safety recall systems like those managed by the NHTSA were not in place for vehicles of this era. Any issues are typically related to normal wear and tear.
Frequently Asked Questions
What is the correct spark plug gap for a 1940 Chrysler C26?
The recommended spark plug gap can vary based on the specific engine and cylinder head (iron vs. aluminum). Some sources indicate a gap of .025 inches for models with aluminum heads. Others for similar Chrysler engines of the era suggest .035 inches. Always verify the correct specification for your engine and use a feeler gauge to set the gap before installation.
Which brand of spark plug is best for my classic Chrysler?
Champion is a historically accurate and highly recommended brand for your vehicle. They were an original supplier to Chrysler and their standard copper plugs are designed to work perfectly with your car's ignition system.
How often should I change the spark plugs?
For a vintage car that may not be driven daily, a good rule is to inspect the spark plugs annually and replace them every few thousand miles or every couple of years. Unlike modern cars with 100,000-mile plugs, the plugs in your C26 work harder in a less controlled environment and benefit from more frequent changes.
Can I replace the spark plugs myself?
Yes, this is a very simple job for a DIY mechanic. The engine bay of a 1940 Chrysler offers excellent access to the spark plugs. The key is to work on one plug at a time to avoid mixing up the spark plug wires.
Technical Specifications
Compatible plugs include Champion J8C and RH10C. The required type is a standard copper-core plug. The spark plug gap should be set before installation, typically to .025" for engines with aluminum heads.
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.