A Guide to the Distributor Cap for the 1947-1951 Studebaker Commander
Ensure your classic Studebaker's ignition runs smoothly with the right replacement distributor cap.
- A failing distributor cap will cause misfires, hard starting, stalling, and rough running.
- For 1951 models, verify if you have the inline-6 or the new V8 engine, as they use different caps.
- Always replace the distributor rotor at the same time as the cap for a complete tune-up.
- Standard Ignition is a reputable aftermarket brand offering quality replacement caps with durable materials like brass terminals.
Signs of a Failing Distributor Cap
A distributor cap is a wear item, meaning it will eventually need to be replaced. When a cap starts to fail, it can cause several noticeable engine problems. The most common cause of failure is age, leading to cracks in the plastic housing or corrosion on the metal terminals inside.
- Engine Misfires or Rough Idle: You may feel the engine stumble or shake, especially when idling. This happens when spark fails to reach a cylinder consistently.
- Hard Starting: The engine may crank for a long time before it starts, or it might not start at all. This can be worse in cold or damp weather.
- Stalling and Backfiring: A faulty cap can interrupt the power to the spark plugs, causing the engine to stall unexpectedly. You might also hear a pop or backfire from the exhaust.
- Engine Shaking: Beyond a rough idle, a bad cap can cause the entire vehicle to shake because the engine's cylinders are not firing correctly.
Check for Cracks and Corrosion
You can often see problems with a visual inspection. Look for fine black lines on the inside of the cap, which are signs of carbon tracking. Also check for cracks, moisture, or white or green corrosion on the metal terminals.
Choosing the Right Aftermarket Cap
For a classic vehicle like the 1947-1951 Studebaker Commander, original factory parts are virtually non-existent. The market today consists of New Old Stock (NOS) parts, which are rare and expensive, and modern aftermarket parts. Aftermarket brands are the most common and practical choice for keeping these cars on the road.
Standard Ignition (SMP) is a well-regarded aftermarket manufacturer that has been making ignition parts since 1919. Their products are designed to meet or exceed original equipment (OE) specifications. Standard Ignition caps are typically made from a durable polyester resin to resist heat and electrical breakdown. Many feature solid brass terminals, which provide better electrical connections and resist corrosion better than aluminum.
Engine Differences in 1951
Be aware that 1951 was a transition year for the Commander. It was available with the traditional inline-six engine, but also with a new overhead-valve V8. These two engines use different distributors and therefore require different distributor caps. Always verify which engine your 1951 Commander has before ordering a part.
Distributor Cap Replacement Cost
Replacing the distributor cap is an affordable and straightforward job. The cost of the part itself is low, and labor at a professional shop is minimal.
| Part Type | Estimated Cost |
|---|---|
| New Aftermarket (Standard Ignition) | $18.86 - $56.70 |
| Shop Labor | $50 - $100 |
Frequently Asked Questions
Can I replace the distributor cap myself?
Yes, this is a very simple job for a DIY mechanic. The cap is held on by two clips and is easily accessible on top of the engine. The only tools needed are typically a screwdriver and your hands. The key is to transfer the spark plug wires from the old cap to the new cap one at a time to maintain the correct firing order.
Should I replace any other parts with the distributor cap?
It is highly recommended to replace the distributor rotor at the same time as the cap. The rotor is the spinning part inside the cap that actually distributes the spark. It is a low-cost part and is exposed during the cap replacement. Replacing both at the same time is considered a standard part of an ignition tune-up.
How often does a distributor cap need to be replaced?
There is no strict replacement interval for a classic car that sees limited use. However, the distributor cap and rotor should be inspected during every tune-up. They are wear-and-tear items that will eventually fail due to heat and high voltage. It's good practice to replace them whenever you replace your spark plugs and wires.
What is the difference between the available Standard Ignition caps?
The price variation ($18.86 - $56.70) for the available caps often relates to materials or what's included. More expensive caps might be made from premium, higher-dielectric materials for better performance and longevity. Some higher-priced options may also be kits that include a new distributor rotor.
Technical Specifications
Engine Type: Inline-6 (1947-1951), V8 (1951). Firing Order (6-Cyl): 1-5-3-6-2-4. Terminal Material: Brass recommended.
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.