A Practical Guide to Spark Plugs for the 1967-1979 MG Midget
Understanding the right plugs for your 1275cc or 1500cc engine is key to a happy Midget.
- First, identify your engine: 1275cc (1967-74) or 1500cc (1975-79) to buy the correct plugs.
- Standard copper plugs from NGK or Champion are the most recommended choice for stock engines.
- Always check and set the spark plug gap to 0.025 inches for a standard points ignition before installation.
- Black, sooty plugs are a sign of a rich fuel mixture or weak spark, not a defective plug.
Engine-Specific Plugs are a Must
Before buying spark plugs for a 1967-1979 MG Midget, you must know which engine is in your car. There was a major change during this period, and the two engines use different plugs.
- 1967-1974 MG Midget: These models have the 1275cc A-series engine.
- 1975-1979 MG Midget: These later models have the 1500cc Triumph engine.
Installing the wrong spark plug can lead to poor performance and potential engine damage. Always verify your car's year and engine before purchasing.
Choosing the Right Aftermarket Spark Plug
For a classic car like the MG Midget, newer technology isn't always better. The original ignition systems were designed for simple, effective copper-core spark plugs. For most owners, these remain the best choice.
Recommended Standard Plugs
These are the go-to choices for reliability and performance in a stock Midget. They are inexpensive and perform excellently with the original ignition system. Many owners consider NGK and Champion to be the top choices for British classic cars.
- For 1275cc (1967-1974): NGK BP6ES or Champion N9YC
- For 1500cc (1975-1979): NGK BP5ES or Champion N12Y
Modern Alternative Plugs (Iridium/Platinum)
Brands like Bosch, Denso, and NGK offer modern plugs with platinum or iridium tips. These are designed to last longer and provide a consistent spark. While they can work in a Midget, they are more expensive and may not offer a noticeable performance benefit unless you have upgraded to a high-energy electronic ignition system. For a stock car with a standard coil and points, traditional copper plugs are often the most reliable option.
Pro Tip: Reading Your Plugs
Don't just throw away your old plugs! Their condition tells a story. A healthy plug will have a light tan or grayish deposit. Black, sooty plugs indicate a rich fuel mixture or a weak spark. Oily black deposits can point to worn piston rings or valve guides. A white or blistered appearance means the engine is running too hot or lean.
Aftermarket Spark Plug Cost
| Plug Type | Typical Price (per plug) | Best For |
|---|---|---|
| Standard Copper (NGK, Champion) | $3.50 - $7.00 | Stock engines, originality, best value |
| Platinum / Iridium (Bosch, NGK, Denso) | $7.00 - $16.38 | Modified engines with upgraded electronic ignition |
Frequently Asked Questions
What is the correct spark plug gap for my MG Midget?
For a stock Midget with a traditional points-based ignition, the correct spark plug gap is 0.025 inches. If you have upgraded to an electronic ignition system, you can often open the gap to between 0.030" and 0.035" for a potentially stronger spark, but you should consult the ignition system's documentation. Always check the gap with a feeler gauge before installation.
Are expensive iridium spark plugs better for my Midget?
Not necessarily. For a stock engine and ignition, a standard copper plug from NGK or Champion is the proven, reliable choice. Iridium plugs cost more and their benefits are most realized in high-energy ignition systems, which are not standard on these cars. Stick with what the car was designed for unless you've made significant upgrades.
Why do my spark plugs get black and sooty?
This is called carbon fouling and it's a very common issue. It is almost always a symptom of another problem, not a faulty spark plug. The most common causes are an overly rich fuel mixture from the carburetors needing adjustment or a weak spark from an aging coil, worn distributor points, or bad plug wires.
How often should I change the spark plugs?
Unlike modern cars that can go 100,000 miles, spark plugs in a classic like the Midget are a regular maintenance item. It's good practice to check them during regular tune-ups and replace them every 6,000 to 12,000 miles, or annually, depending on how much you drive. Given their low cost, frequent replacement is cheap insurance for a smooth-running engine.
Helpful Videos
Technical Specifications
OEM Part Numbers: N9YC N12Y BP6ES BP5ES
Recommended Spark Plug Gap (Points Ignition): 0.025 in. (0.635 mm)
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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.