A Guide to Aftermarket Spark Plugs for the 1963-1966 Glas 1304
Keep your rare classic's innovative engine firing on all cylinders with the right set of new spark plugs.
- Standard copper spark plugs from brands like Autolite or Champion are the recommended and most cost-effective choice for the Glas 1304.
- Always replace all four spark plugs as a set to ensure even engine performance.
- Check and adjust the spark plug gap to approximately 0.025 inches before installation.
- No recalls or specific widespread spark plug issues are documented for the Glas 1304 due to its rarity.
Signs of Failing Spark Plugs in Your Glas 1304
Even a well-engineered classic like the Glas 1304 will let you know when its spark plugs are worn out. Because these cars are rare, specific common problems are not widely documented. However, you can watch for universal signs of spark plug failure.
- Rough Idle: If your Glas feels shaky or uneven when stopped, it could be due to inconsistent sparks.
- Trouble Starting: Worn plugs have a harder time creating a strong spark, making the engine difficult to start, especially when cold.
- Engine Misfires: You might feel a hesitation or stumble during acceleration. This happens when a cylinder fails to fire correctly.
- Reduced Fuel Economy: Inefficient combustion from bad plugs means the engine uses more fuel to produce the same amount of power.
- Poor Performance: A general lack of power or a sluggish feeling can be traced back to plugs that are no longer firing optimally.
No Known Recalls or Bulletins
Searches for official recalls or Technical Service Bulletins (TSBs) from the NHTSA for the Glas 1304 regarding spark plugs came up empty. This is expected for a low-production German vehicle from the 1960s in the North American market.
Choosing the Right Aftermarket Spark Plugs
Finding original equipment (OEM) spark plugs from the 1960s is nearly impossible. Thankfully, modern aftermarket brands offer direct-fit replacements that provide reliable performance. For a classic car like the Glas 1304, standard copper plugs are often the best choice as they are similar to what the vehicle would have used originally.
Brand & Quality Tiers
Your main choices will be between Autolite and Champion. Both are established brands that offer compatible plugs for your Glas.
- Standard/Economy (Autolite, Champion Copper): These are excellent, affordable choices that perform well in classic cars. Many owners of vintage vehicles prefer the performance and reliability of standard copper plugs over more modern, expensive types. Some mechanics and owners have preferences, with some finding Autolite more reliable and less prone to fouling in older engines, while others have had good experiences with Champion. For a stock Glas 1304, a standard copper plug from either brand is a solid choice.
- Premium (Autolite Platinum, Champion Iridium): While available, platinum or iridium plugs are generally not necessary for the Glas 1304's ignition system. These plugs are designed for modern high-energy ignition systems and may not provide any noticeable benefit in your classic, making the extra cost unnecessary. Sticking with the OEM-style copper plug is often the safest bet.
Pro Tip: Always check the spark plug gap before installation. Even if the plugs are pre-gapped, they can be knocked out of spec during shipping. The correct gap for a Glas 1304 is approximately 0.025 inches, but always verify with a service manual if you have one.
Aftermarket Spark Plug Cost for 1963-1966 Glas 1304
| Brand/Tier | Price Range (per plug) | Notes |
|---|---|---|
| Autolite / Champion (Standard Copper) | $3.68 - $5.99 | Recommended for original performance. Excellent value and reliability. |
| Autolite / Champion (Platinum/Iridium) | $5.97 - $12.36 | Longer life, but may not offer performance benefits on this specific engine. |
Frequently Asked Questions
How often should I change the spark plugs on my Glas 1304?
For a classic car that is likely not driven daily, a good rule of thumb is to inspect the spark plugs annually and replace them every 10,000 to 15,000 miles or every 2-3 years, whichever comes first. This helps prevent issues from carbon buildup and electrode wear.
Should I use anti-seize on the spark plug threads?
Yes, it is a good practice on these engines. Applying a small amount of anti-seize compound to the plug threads helps prevent them from getting stuck (galling) in the aluminum cylinder head, making future changes much easier.
Do I need special tools to change the spark plugs?
You will need a standard ratchet, a spark plug socket (which has a rubber insert to protect the plug's ceramic), and a torque wrench to ensure you tighten the new plugs to the correct specification. You will also need a feeler gauge or gapping tool to check the gap.
Is it better to use hotter or colder spark plugs?
For a stock engine, you should stick with the standard heat range recommended by the aftermarket manufacturer (e.g., Autolite 63 or Champion N9YC). Using a plug that is too hot can lead to engine damage, while a plug that is too cold can foul easily. Unless your engine is heavily modified, the standard replacement is the correct choice.
Technical Specifications
Cross-reference parts include Autolite 63, Autolite AP63, and Champion N9YC. The recommended spark plug gap is approximately 0.025 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.