Choosing the Right Spark Plugs for Your 1972-1973 Subaru Deluxe
Keep your classic Subaru's engine running smoothly with the correct new spark plugs.
- Standard copper spark plugs are the best and most cost-effective choice for the Deluxe's vintage engine.
- Expect to replace copper plugs every 15,000-20,000 miles for optimal performance.
- Common compatible part numbers include NGK B6HS, Champion L87YC, and Denso W20FS-U.
- Replacement is a simple DIY task that requires basic tools and about 30 minutes.
Signs of Failing Spark Plugs in Your Deluxe
Because of the simple, carbureted engine design in your 1972-1973 Subaru Deluxe, the symptoms of worn spark plugs are usually quite noticeable. If your plugs are old, fouled, or have an incorrect gap, you might experience several issues that degrade your driving experience.
Common Failure Symptoms:
- Rough Idling: Your engine may shake or sound uneven when stopped.
- Difficulty Starting: The engine may take longer to crank and start, especially in cold weather.
- Poor Acceleration: The car may feel sluggish or hesitant when you press the gas pedal.
- Engine Misfires: You might feel a jerking or stumbling from the engine, often accompanied by a popping sound from the exhaust.
- Reduced Fuel Economy: Worn plugs lead to incomplete combustion, forcing you to visit the gas station more often.
Choosing the Right Aftermarket Spark Plugs
For a vintage vehicle like the 1972-1973 Deluxe, finding original OEM parts is nearly impossible. Aftermarket spark plugs are the standard replacement, and modern quality is excellent. The key is choosing the right type for your classic engine.
Brand Tiers & Material Types
The brands available—NGK, Denso, Champion, and Autolite—are all reputable manufacturers with decades of experience. For your Deluxe, the brand is less important than choosing the correct material and heat range.
- Standard Copper Plugs (Recommended): These are the most cost-effective option and are similar to the original technology used in your car. Brands like NGK (B6HS), Champion (L87YC), and Denso (W20FS-U) offer standard copper plugs that are an excellent match for the Deluxe's engine. They provide reliable performance but have a shorter lifespan, typically needing replacement every 15,000-20,000 miles.
- Iridium/Platinum Plugs: While available from brands like NGK and Denso, these long-life plugs are generally not necessary for a classic, carbureted engine. They are more expensive and the performance benefits seen in modern, computer-controlled engines will not be realized in your Deluxe. Sticking with standard copper plugs is the most practical and economical choice.
Aftermarket Spark Plug Cost for 1972-1973 Subaru Deluxe
| Brand/Type | Estimated Price (per plug) |
|---|---|
| Autolite / Denso (Standard Copper) | $3.68 - $5.00 |
| Champion / NGK (Standard Copper) | $4.00 - $9.00 |
| NGK / Denso (Iridium/Platinum) | $9.00 - $16.38 |
Note: Prices are estimates and can vary based on the retailer and specific part number.
Frequently Asked Questions (FAQ)
How often should I change the spark plugs on my Subaru Deluxe?
For standard copper spark plugs, a good interval is every 15,000 to 20,000 miles or every two to three years. Since this is a classic car that may not be driven daily, time can degrade the plugs as much as mileage.
Are more expensive iridium plugs worth it for my classic Subaru?
Generally, no. The main benefit of iridium plugs is their long service life in modern high-energy ignition systems. Your 1972-1973 Deluxe's simpler ignition system was designed for copper plugs, and they will provide excellent performance at a much lower cost.
Can I replace the spark plugs myself?
Yes, absolutely. Replacing spark plugs on the Deluxe's engine is a very straightforward task for a DIY mechanic. Access is typically easy, and it only requires a few basic tools like a spark plug socket and a ratchet.
Do all four brands (Autolite, Champion, Denso, NGK) make a compatible plug?
Yes, all four brands offer spark plugs that cross-reference to the original specifications for your vehicle. The most common cross-reference numbers are NGK B6HS, Champion L87YC, Denso W20FS-U, and Autolite 425.
Technical Specifications
Thread Diameter: 14mm, Thread Reach: 12.7mm (1/2"), Hex Size: 21mm (13/16"), Seat Type: Flat, Recommended Material: Copper Core. Common aftermarket part numbers include NGK B6HS, Champion L87YC, Denso W20FS-U, and Autolite 425.
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.