1978 Mercury Cougar Spark Plugs

Your 1978 Mercury Cougar might be the best vehicle you’ve ever owned. Or you may just be struggling to keep it highway-approved. No matter the situation, Advance Auto Parts has the Spark Plugs you desperately need.

We currently carry 29 Spark Plugs to choose from for your 1978 Mercury Cougar, and our inventory prices range from as little as $2.79 up to $52.99.

On top of low prices, Advance Auto Parts offers 8 different trusted brands of Spark Plugs for the 1978 Mercury Cougar. We only sell parts from trusted brands like ACDelco so that you can find quality parts you can count on.

Don’t take our word for it – check out customer ratings and reviews to buy with confidence. We have 2,306 reviews on our Spark Plugs for the 1978 Mercury Cougar from previous customers.

Have parts delivered straight to your home, or find the nearest Advance Auto Parts store to check out our Spark Plugs stock in-person!

Spark Plugs for Your 1978 Mercury Cougar

NGK – OE Series V-Power Nickel Spark Plug: V-Groove Tip Design, UR4 (Part No.6630)

OE Series V-Power Nickel Spark Plug: V-Groove Tip Design, UR4

from

$4.99
NGK V-Power spark plugs offer reliable performance and improved ignitability over standard nickel plugs. Engineered specifically for OE applications, the special V-cut nickel alloy center electrode and concave ground electrode of NGK’s V-Power spark plug increases ignitability providing quicker starts and smoother idle. NGK’s legendary high grade alumina silicate ceramic creates a stronger insulator for optimal dielectric performance. Trivalent metal plating ensures superior anti-corrosion and anti-seizing properties.

Product Features:
  • ACTUAL OE or EQUIVALENT DESIGN: OEM quality construction nickel alloy center electrode with V-groove provides consistent performance
  • RECOMMENDED USAGE: Best for vehicles with OE nickel alloy plugs, not recommended on vehicles with factory precious metal plugs
  • NGK’s OE CERAMIC TECHNOLOGY: High grade alumina silicate ceramic creates a stronger insulator for optimal dielectric performance
  • SOLID COPPER CORE: 98% pure copper core offers superior heat dissipation, conductivity and ultra wide heat ranges
  • COLD-ROLLED THREADS: Prevents cross-threading and damage to cylinder heads
  • TRIVALENT METAL PLATING: Delivers superior anti-corrosion and anti-seizing properties, ensuring ease of installation and removal
  • Enhanced Ignitability: The V-cut nickel alloy center electrode and concave ground electrode design of NGK V-Power spark plugs provide quicker starts and smoother idle.
  • OE Application Specific: Engineered specifically for Original Equipment (OE) applications, ensuring compatibility and reliable performance.
  • V-Groove Tip Design: The unique V-groove tip design enhances ignitability and overall engine performance.
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NGK – OE Series V-Power Nickel Spark Plug: V-Groove Tip Design, UR45 (Part No.6945)

OE Series V-Power Nickel Spark Plug: V-Groove Tip Design, UR45

from

$4.99
NGK V-Power spark plugs offer reliable performance and improved ignitability over standard nickel plugs. Engineered specifically for OE applications, the special V-cut nickel alloy center electrode and concave ground electrode of NGK’s V-Power spark plug increases ignitability providing quicker starts and smoother idle. NGK’s legendary high grade alumina silicate ceramic creates a stronger insulator for optimal dielectric performance. Trivalent metal plating ensures superior anti-corrosion and anti-seizing properties.

Product Features:
  • ACTUAL OE or EQUIVALENT DESIGN: OEM quality construction nickel alloy center electrode with V-groove provides consistent performance
  • RECOMMENDED USAGE: Best for vehicles with OE nickel alloy plugs, not recommended on vehicles with factory precious metal plugs
  • NGK’s OE CERAMIC TECHNOLOGY: High grade alumina silicate ceramic creates a stronger insulator for optimal dielectric performance
  • SOLID COPPER CORE: 98% pure copper core offers superior heat dissipation, conductivity and ultra wide heat ranges
  • COLD-ROLLED THREADS: Prevents cross-threading and damage to cylinder heads
  • TRIVALENT METAL PLATING: Delivers superior anti-corrosion and anti-seizing properties, ensuring ease of installation and removal
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ACDelco – Copper Core Spark Plug: Original Equipment Replacement (Part No.R45TSX)

Copper Core Spark Plug: Original Equipment Replacement

from

$4.99
ACDelco Professional Conventional Spark Plugs are designed for reliability and efficient performance, and are a high quality replacement for many vehicles on the road today. Their high-quality copper cores and outstanding suppression characteristics deliver reliable performance. They are also available for Marine applications. These premium aftermarket replacement spark plugs are manufactured to meet your expectations for fit, form, and function.

Product Features:
  • Black Onyx coating helps reduce corrosion
  • Copper core provides great heat transfer and helps maximize plug durability
  • Ribbed suppressor seal extends resistance and helps prevent spark ‘flash over’ and misfires
  • Nickel-chrome alloy sheathing helps prevent corrosion on center electrode
  • Available for use in Marine applications
  • Some ACDelco GM Original Equipment parts may have formerly appeared as GM Genuine Parts (OE) or ACDelco Professional
  • ACDelco GM Original Equipment parts are designed, engineered and tested to rigorous standards, and are backed by General Motors
  • GM Engineers design and validate OE parts specifically for your Chevrolet, Buick, GMC, or Cadillac vehicle
  • GM regularly updates production and service part designs to integrate new materials and technologies
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Accel – High-Performance Shorty Spark Plugs for Header Clearance (Part No.8199)

High-Performance Shorty Spark Plugs for Header Clearance

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$52.99
ACCEL’s patented race proven spark plugs in a Shorty configuration. The overall length has been reduced 3/16 in to 3/8 in (depending on the specific spark plug) to gain critical air gap between the spark plug boot and the exhaust manifold or header tube. This helps eliminate burning the spark plug boot or dimpling the header tube. The shorter spark plug length also can make it easier to install an remove the spark plugs in certain applications where there is not a lot of room to fit a socket or move a wrench around. ACCEL Shorty Spark Plugs are made with a Copper core which is a better conductor than Platinum and Iridium. They deliver a stronger spark especially in high performance applications where high combustion pressures are present. Copper is much better at dissipating heat than other materials which lessens the chance of a misfire. ACCEL Shorty Spark Plugs are gapable allowing you to open the gap exposing a larger flame kernel or close it if needed for high boost applications. All ACCEL Shorty Spark Plugs have machine rolled threads allowing for a more precise thread engagement and torque retention.

Product Features:
  • Shorty Spark Plugs For Tubular Exhaust Headers
  • Eliminates Dimpling Headers For Added Clearance
  • Improves Spark Plug Access To Fit Socket Or Wrench
  • Shorter Overall Plug Length Vs. OE Style Plug
  • Copper Core Center Electrode
  • Projected Tip
  • Helps Eliminate Burned Spark Plug Boots
  • Shorty Header Spark Plug
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Champion – Copper Plus Spark Plug: Dependable Performance, OE Replacement, RV17YC (Part No.25)

Copper Plus Spark Plug: Dependable Performance, OE Replacement, RV17YC

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$3.49
Dependable performance. This Champion® spark plug features a copper core electrode that provides increased conductivity and heat control for good overall wear.

Product Features:
  • Copper Plus – Dependable Performance and Durability
  • Copper core center electrode allows for accurate control of heat range for longer life
  • Superior corrosion resistance
  • Built to ISO and SAE standards for proven performance
  • Built to ISO and SAE standards for proven performance
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NGK – Platinum Spark Plug – Enhanced Durability & Fuel Efficiency (Part No.3207)

Platinum Spark Plug - Enhanced Durability & Fuel Efficiency

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$5.99
NGK G-Power Platinum spark plugs are the best single platinum spark plugs at an economical price. G-Power plugs feature a fine wire platinum center electrode and a trapezoidal cut ground electrode that offers increased durability, improved fuel efficiency, lower emissions, faster starts and quicker acceleration over conventional nickel spark plugs. An excellent upgrade for vehicles which used nickel alloy spark plugs originally. For better performance consider upgrading to a NGK Iridium IX plug. For even greater performance consider upgrading to a NGK RUTHENIUM HX plug.

Product Features:
  • SINGLE PLATINUM TIP: Fine wire 0.6 millimeter platinum tip center electrode ensures improved durability and a consistently stable spark
  • PLATINUM ALLOY: G-Power platinum provides exceptional value with increased performance and longer service intervals than factory nickel plugs
  • TRAPEZOIDAL CUT GROUND ELECTRODE: Reduces quenching design produces improved ignitability and performance
  • SOLID COPPER CORE: 98% pure copper core offers superior heat dissipation, conductivity and ultra wide heat ranges
  • COLD-ROLLED THREADS: Prevents cross-threading and damage to cylinder heads
  • RECOMMENDED USAGE: Lower cost alternative to double precious metal spark plugs or as an upgrade to OE nickel alloy spark plugs
  • Improved Fuel Efficiency: Designed to improve fuel efficiency, helping you save on fuel costs over time.
  • Lower Emissions: These spark plugs contribute to lower emissions, making them an environmentally friendly choice.
  • Faster Starts and Quicker Acceleration: Experience faster starts and quicker acceleration, enhancing your vehicle’s overall performance.
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Accel – U-Groove Resistor Blister-Pak: Spark Plug (Part No.8179)

U-Groove Resistor Blister-Pak: Spark Plug

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$48.49
ACCEL HP Spark Plugs are made with a Copper core which is a better conductor than Platinum and Iridium. They deliver a stronger spark especially in high performance applications where high combustion pressures are present. Copper is much better at dissipating heat than other materials which lessens the chance of a misfire. ACCEL HP Spark Plugs are gapable allowing you to open the gap exposing a larger flame kernel or close it if needed for high boost applications. All ACCEL HP Spark Plugs have machine rolled threads allowing for a more precise thread engagement and torque retention.

Product Features:
  • The Copper core is a better conductor than Iridium or Platinum plugs
  • Copper dissipates heat much better than other materials
  • C
  • Unlike Iridium or Platinum plugs, the ACCEL HP plugs are gapable
  • Machine rolled threads for precise thread engagement
  • Stock heat range
  • Whether using on the street or on the strip, ACCEL HP Copper Core spark plugs deliver!
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ACDelco – Copper Core Spark Plug: Original Equipment Replacement (Part No.R45TS)

Copper Core Spark Plug: Original Equipment Replacement

from

$4.99
ACDelco GM Original Equipment Conventional Spark Plugs are designed, engineered, and tested to rigorous standards, and are backed by General Motors. These Conventional Spark Plugs are designed for reliability and efficient performance, and are a high quality replacement for many vehicles on the road today. Their high-quality copper cores and outstanding suppression characteristics deliver reliable performance. They are also available for Marine applications. These premium aftermarket replacement spark plugs are manufactured to meet your expectations for fit, form, and function. ACDelco GM Original Equipment parts are the true OE parts installed during the production of or validated by General Motors for GM vehicles. Some ACDelco GM Original Equipment parts may have formerly appeared as GM Genuine Parts (OE) or ACDelco Professional.

Product Features:
  • GM regularly updates production and service part designs to integrate new materials and technologies
  • High-Quality Copper Core: Designed with high-quality copper cores for reliable and efficient performance.
  • Nickel Center Electrode Tip: Features a nickel center electrode tip for enhanced durability and performance.
  • Outstanding Suppression Characteristics: Delivers reliable performance with excellent suppression characteristics.
  • Versatile Applications: Providing high-quality replacement options for various vehicles.
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Autolite – Copper Spark Plug: Delivers Quick Starts, Good Fuel Economy, Smooth Acceleration (Part No.26)

Copper Spark Plug: Delivers Quick Starts, Good Fuel Economy, Smooth Acceleration

from

$3.49
Autolite has over 100 years of engineering experience and has sold over 11 billion plugs. Guaranteed to deliver quick starts, good fuel economy and smooth acceleration, Autolite Copper Core spark plugs are designed to meet or exceed OES design requirements. Consider upgrading to Autolite Platinum, Double Platinum or Iridium XP plugs for improved engine performance. Copper core plugs are the industry standard.

Product Features:
  • Copper-glass seal bonds insulator, terminal post center electrode together; assures full required voltage at spark gap; gas-tight seal (100% leak proof)
  • Multi-rib insulator reduces danger of “flash-over”
  • One-piece terminal post adds strength
  • Resistor reduces radio frequency interference (RFI) and electrode erosion
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Autolite – Platinum Spark Plug: Fires Cleaner, Easier Starts, Quicker Acceleration (Part No.AP26)

Platinum Spark Plug: Fires Cleaner, Easier Starts, Quicker Acceleration

from

$4.79
Autolite has over 100 years of engineering experience and has sold over 11 billion plugs. Designed and engineered in the USA, Autolite Platinum spark plugs provide a center wire platinum firing tip which provides reduced gap erosion, fewer misfires, better performance and increased durability. Consider upgrading to Autolite Double Platinum or Iridium XP spark plugs for increased performance.

Product Features:
  • High nickel alloy side electrode maintains precise gap
  • Full platinum tip assures virtually no gap erosion for long life
  • Necked-down center electrode fires quicker, cleaner with less voltage for easier starts, quicker acceleration and improved fuel economy (as compared to standard plugs)
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ACDelco – RAPIDFIRE Premium Platinum Tip Copper Core Spark Plug: Reduces Misfires & Enhances Durability (Part No.2)

RAPIDFIRE Premium Platinum Tip Copper Core Spark Plug: Reduces Misfires & Enhances Durability

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$6.79
ACDelco Gold (Professional) RAPIDFIRE Spark Plugs are a high quality alternative to Original Equipment (OE) parts. These RAPIDFIRE Single Platinum Performance Spark Plugs are designed for everyday use and are a high quality replacement for many vehicles on the road today. These premium aftermarket spark plugs have high-quality suppressors that help prevent misfiring, an improved plug to boot seal, and a pure copper core for greater durability. These premium aftermarket replacement spark plugs are manufactured to meet your expectations for fit, form, and function. ACDelco Gold (Professional) parts are manufactured to meet your expectations for fit, form, and function, making them a smart choice for General Motors vehicles, as well as most makes and models, including special applications. These high-quality parts are backed by General Motors. Some ACDelco Gold parts may have formerly appeared as ACDelco Professional.

Product Features:
  • Solid state suppressor, with two-piece glass and brass seal, can help reduce radio frequency interference, regulates spark energy for long electrode life, and helps protect against high combustion pressures
  • Pure copper core provides great heat transfer and helps maximize plug durability
  • Platinum on center electrode enables superior spark characteristics and can reduce voltage requirements of the ignition system
  • Ribless insulator helps optimize plug to boot sea
  • Some ACDelco Gold parts may have formerly appeared as ACDelco Professional
  • Premium aftermarket replacement part
  • Manufactured to meet specifications for fit, form, and function for General Motors vehicles as well as most makes and models
  • High-Quality Suppressors: ACDelco Gold RAPIDFIRE Spark Plugs feature high-quality suppressors that help prevent misfiring, ensuring reliable performance for everyday use.
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Autolite – Double Platinum Spark Plug: Platinum Firing, Superior Durability, Longer Life (Part No.APP26)

Double Platinum Spark Plug: Platinum Firing, Superior Durability, Longer Life

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$6.49
With over 100 years of engineering expertise and more than 11 billion plugs sold, Autolite delivers exceptional quality. Designed and engineered in the USA, these spark plugs feature platinum-to-platinum firing, virtually eliminating gap erosion and reducing misfires. The OE design and full-platinum tips on both the center and side electrodes optimize engine performance for a longer life and improved fuel economy. The platinum ball welding process ensures a consistent point of contact for enhanced adhesion, while the tapered seat type further contributes to the plug’s superior durability.

Product Features:
  • Works to optimize engine performance for a longer life and improved fuel economy
  • OE design
  • Full-platinum tips; platinum on both the center and side electrodes to promote reduced gap wear
  • Platinum ball welding process provides a consistent point of contact for enhanced adhesion
  • Engineered in the USA: Backed by over 100 years of engineering expertise and more than 11 billion plugs sold, Autolite spark plugs are designed and engineered in the USA for exceptional quality and reliability.
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E3 – DiamondFIRE Automotive Spark Plug: More Power, Saves Gas (Part No.E3.42)

DiamondFIRE Automotive Spark Plug: More Power, Saves Gas

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$7.49
The Spark Plugs are the product of years of fundamental research in the combustion field. The unique patented electrode configuration of these new The spark plugs increases the amount of combustion pressure created during each power stroke of an engine, which results in a marked increase in power output, fuel economy, and reduced emissions in all gasoline engines. E3.42 is a 14mm, 0.460 reach plug with a taper seat. It fits domestic applications in the 80s to early 90s, and is widely stocked in automotive retail stores. The automotive plugs have three legs securing the Diamond FIRE electrode to the shell. This allows for excellent heat transfer, and helps to create more turbulence in the cylinder. The patented Diamond FIRE side wire is proven to increase power, reduce fuel consumption and improve hydrocarbon emissions in long-term use.

Product Features:
  • E3’s Diamond Fire edge to edge ground electrode provides maximum performance with increased efficiency and a faster more complete burn.
  • Smoother Acceleration & Idle – The faster flame initiated by the The spark plug results in a more complete burn of the ingested fuel charge. More pressure is created against the piston more fuel is put to work
  • Energy – Power output improved up to 6% on average in the typical operating ranges. Results will vary.
  • Efficiency – The “diamond shaped” side wire electrode projects the combustion spark in a way that more quickly ignites the air/fuel mixture, thereby creating a significantly faster and larger flame kernel. The result is that more fuel is put to work durin
  • E3’s patented Diamond Fire Technology provides a cleaner burning combustion, which translates into fuel savings and reduced engine carbon deposits
  • The Spark Plugs are pre-gapped at the factory and cannot be adjusted.
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Autolite – Copper Spark Plug: Delivers Quick Starts, Good Fuel Economy, Smooth Acceleration (Part No.666)

Copper Spark Plug: Delivers Quick Starts, Good Fuel Economy, Smooth Acceleration

from

$3.49
With over 100 years of engineering expertise and more than 11 billion plugs sold, Autolite continues to set the standard in spark plug technology. Designed and engineered in the USA, these spark plugs feature a copper-glass seal that bonds the insulator, terminal post, and center electrode together, ensuring full required voltage at the spark gap with a 100% leak-proof, gas-tight seal. The multi-rib insulator reduces the risk of flash-over, while the one-piece terminal post adds strength and durability. Additionally, the built-in resistor minimizes radio frequency interference (RFI) and electrode erosion, making these plugs a reliable choice for any vehicle. The tapered seat type further enhances the plug’s performance, providing quick starts, good fuel economy, and smooth acceleration.

Product Features:
  • Copper-glass seal bonds insulator, terminal post center electrode together; assures full required voltage at spark gap; gas-tight seal (100% leak proof)
  • Multi-rib insulator reduces danger of “flash-over”
  • One-piece terminal post adds strength
  • Resistor reduces radio frequency interference (RFI) and electrode erosion
  • Quick Starts and Smooth Acceleration: Designed to provide quick engine starts and smooth acceleration, enhancing overall driving performance.
  • Good Fuel Economy: Engineered to optimize fuel efficiency, helping you save on fuel costs.
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NGK – G-Power Spark Plug: Single Platinum Tip Design, UR4GP (Part No.2869)

G-Power Spark Plug: Single Platinum Tip Design, UR4GP

from

$6.29
NGK G-Power Platinum spark plugs are the best single platinum spark plugs at an economical price. G-Power plugs feature a fine wire platinum center electrode and a trapezoidal cut ground electrode that offers increased durability, improved fuel efficiency, lower emissions, faster starts and quicker acceleration over conventional nickel spark plugs. An excellent upgrade for vehicles which used nickel alloy spark plugs originally. For better performance consider upgrading to a NGK Iridium IX plug. For even greater performance consider upgrading to a NGK RUTHENIUM HX plug.

Product Features:
  • SINGLE PLATINUM TIP: Fine wire 0.6 millimeter platinum tip center electrode ensures improved durability and a consistently stable spark
  • PLATINUM ALLOY: G-Power platinum provides exceptional value with increased performance and longer service intervals than factory nickel plugs
  • TRAPEZOIDAL CUT GROUND ELECTRODE: Reduces quenching design produces improved ignitability and performance
  • SOLID COPPER CORE: 98% pure copper core offers superior heat dissipation, conductivity and ultra wide heat ranges
  • COLD-ROLLED THREADS: Prevents cross-threading and damage to cylinder heads
  • RECOMMENDED USAGE: Lower cost alternative to double precious metal spark plugs or as an upgrade to OE nickel alloy spark plugs
  • Trapezoidal Cut Ground Electrode: Improves fuel efficiency, lowers emissions, and provides faster starts and quicker acceleration.
  • Economical Upgrade: Ideal for vehicles originally equipped with nickel alloy spark plugs, offering a cost-effective performance boost.
  • Enhanced Durability: Designed to last longer than traditional nickel spark plugs, reducing the need for frequent replacements.
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NGK – Iridium IX Spark Plug: Single Iridium Fine Wire, UR4IX (Part No.7401)

Iridium IX Spark Plug: Single Iridium Fine Wire, UR4IX

from

$11.99
NGK Iridium IX spark plugs are specifically designed for the performance enthusiast. Iridium IX provides outstanding acceleration, high fuel efficiency and durability. NGK Iridium IX plugs offer extreme ignitability and exceptional anti-fouling. Tapered cut ground electrode provides improved starting, idling and throttle response. The Iridium fine wire center electrode’s durability is six times harder than platinum. Iridium alloy’s extremely high melting point is perfect for today’s engines. For even greater performance consider upgrading to an NGK Ruthenium HX plug.

Product Features:
  • SINGLE IRIDIUM TIP: Fine wire 0.6 millimeter iridium tip center electrode ensures high durability and a consistently stable spark
  • IRIDIUM ALLOY CENTER ELECTRODE: Iridium’s density (6x that of platinum) and extremely high melting point is perfect for modern high efficiency engines
  • TAPERED CUT GROUND ELECTRODE: Reduced quenching design produces outstanding ignitability, improved acceleration, fuel efficiency and durability
  • SOLID COPPER CORE: 98% pure copper core offers superior heat dissipation, conductivity and ultra wide heat ranges
  • TRIVALENT METAL PLATING: Delivers superior anti-corrosion and anti-seizing properties, ensuring ease of installation and removal
  • RECOMMENDED USAGE: Modified or high performance applications, or as an upgrade to OE nickel alloy spark plugs
  • High Performance: The Iridium IX Spark Plug is designed for the performance enthusiast, providing outstanding acceleration and exceptional anti-fouling.
  • Improved Ignitability: With extreme ignitability, this spark plug ensures improved starting, idling and throttle response.
  • Fuel Efficiency: The Iridium fine wire center electrode’s durability is six times harder than platinum, which provides high fuel efficiency.
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Autolite – Platinum Spark Plug: Fires Cleaner, Easier Starts, Quicker Acceleration (Part No.AP666)

Platinum Spark Plug: Fires Cleaner, Easier Starts, Quicker Acceleration

from

$4.29
Autolite has over 100 years of engineering experience and has sold over 11 billion plugs. Designed and engineered in the USA, Autolite Platinum spark plugs provide a center wire platinum firing tip which provides reduced gap erosion, fewer misfires, better performance and increased durability. Consider upgrading to Autolite Double Platinum or Iridium XP spark plugs for increased performance.

Product Features:
  • High nickel alloy side electrode maintains precise gap
  • Full platinum tip assures virtually no gap erosion for long life
  • Necked-down center electrode fires quicker, cleaner with less voltage for easier starts, quicker acceleration and improved fuel economy (as compared to standard plugs)
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DENSO – Iridium Power Spark Plug: Maximum Spark Energy, 0.4mm Iridium Tip, ITF16 (Part No.5330)

Iridium Power Spark Plug: Maximum Spark Energy, 0.4mm Iridium Tip, ITF16

from

$10.79
Increased performance with World’s smallest Iridium Center Eletrode (0.4mm).

Product Features:
  • World’s smallest Iridium Center Electrode (0.4mm) for improved spark for maximum combustion
  • Patented 360-degree laser welding assembly process
  • U-groove and taper cut ground electrode to maximize flame propagation.
  • Withstands temperatures greater than 4000┬░ Fahrenheit
  • Burnished nickel plating for high temperature endurance and superior corrosion resistance
  • Wide range of part numbers for thousands of applications, including classic and collector cars
  • Iridium Power
  • Superior Performance: Designed for maximum performance under extreme conditions, this spark plug delivers more horsepower, faster and easier starts, and fewer misfires under heavy loads.
  • Enhanced Fuel Efficiency: The advanced iridium technology of the DENSO Iridium Power spark plug contributes to better fuel efficiency, making it an economical choice for your vehicle.
  • Low Voltage Requirement: This spark plug requires 5,000 volts less to fire compared to conventional spark plugs, ensuring reliable ignition with lower energy consumption.
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Autolite Iridium – Iridium XP Finewire Spark Plug: Improved Durability, More Focused Ignition (Part No.XP26)

Iridium XP Finewire Spark Plug: Improved Durability, More Focused Ignition

from

$9.99
Our best spark plug! Autolite has over 100 years of engineering experience and has sold over 11 billion plugs. Designed and engineered in the USA, the Autolite Iridium XP spark plugs feature an iridium-enhanced 0.6mm finewire design and patented platinum sidewire technology to provide better overall durability and a more focused ignition for enhanced ignitability and performance. Features double Iridium-enhanced alloy technology center electrode for improved durability and wear resistance.

Product Features:
  • 0.6 mm finewire design improves ignitability
  • Patented V-trimmed platinum sidewire technology resists wear
  • OE equivalent design is engineered for every engine
  • Designed for better overall durability with virtually no gap erosion
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ACDelco – Premium Double Platinum Tip Copper Core Spark Plug: Long-Lasting Performance & Durability (Part No.41-905)

Premium Double Platinum Tip Copper Core Spark Plug: Long-Lasting Performance & Durability

from

$9.79
ACDelco Professional Double Platinum Spark Plugs are premium aftermarket plugs, and are a high quality replacement for many vehicles on the road today. With a copper core and double platinum pads on the center electrode, these plugs are designed to deliver long-lasting performance. These premium aftermarket replacement spark plugs are manufactured to meet your expectations for fit, form, and function.

Product Features:
  • One-piece, fired-in suppressor seal blends three glass types for a gas-tight seal that helps reduce radio frequency and engine interference, regulate spark plug energy, and protect against compression pressures for long life
  • Double platinum point pad on center and ground electrode offer excellent durability and consistent voltage demands to help reduce wear on ignition system
  • Pure copper core results in cooler electrode temperature for maximized durability and fouling resistance
  • Some ACDelco GM Original Equipment parts may have formerly appeared as GM Genuine Parts (OE) or ACDelco Professional
  • ACDelco GM Original Equipment parts are designed, engineered and tested to rigorous standards, and are backed by General Motors
  • GM Engineers design and validate OE parts specifically for your Chevrolet, Buick, GMC, or Cadillac vehicle
  • GM regularly updates production and service part designs to integrate new materials and technologies
  • Tapered Seat Design: The tapered seat type ensures a secure fit and optimal sealing in the engine.
  • High-Quality Aftermarket Replacement: Manufactured to meet high standards of fit, form, and function, making it a reliable replacement for many vehicles on the road today.
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Motorcraft – Standard Spark Plug: Enhances Durability & Reduces Fuel Consumption (Part No.SP-425-A)

Standard Spark Plug: Enhances Durability & Reduces Fuel Consumption

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$4.49
Motorcraft Spark Plugs are original equipment on Ford Motor Company vehicles, engineered to meet strict Ford engineering standards for optimal performance and reliability. These spark plugs are matched to specific engines to provide enhanced durability, eliminate misfires, reduce fuel consumption, and optimize emissions. They are resistant to oxidation and arc erosion, feature a multi-rib insulator to protect against misfire, and offer service intervals of up to 100,000 miles. Designed with high-quality materials, Motorcraft Spark Plugs ensure reliable performance for almost any application and are backed by Motorcraft’s Service Parts Warranty. They are an exact fit for Ford, Lincoln, and Mercury vehicles and help prevent false check engine lights, delivering the same performance and reliability as the original components installed during manufacturing.

Product Features:
  • Motorcraft spark plugs are matched to specific engines to provide enhanced durability, eliminate misfires, reduce fuel consumption and optimize emissions.
  • Backed by Motorcraft’s Service Parts Warranty
  • Exact fit for Ford, Lincoln and Mercury vehicles
  • Resistant to oxidation and arc erosion.
  • Multi-rib insulator protects against misfire.
  • Service intervals of up to 100,000 miles.
  • Motorcraft Spark Plugs are designed with high quality materials to provide reliable performance for almost any application.
  • Motorcraft Spark Plugs are what was in the vehicle when it was manufactured
  • Motorcraft ignition components help prevent false check engine lights.
  • Enhanced Durability: Engineered to meet strict Ford engineering standards, these spark plugs are designed to provide long-lasting performance and withstand harsh conditions.
  • Reduces Fuel Consumption: Specifically matched to engines to optimize fuel efficiency, helping you save on fuel costs.
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Champion – Platinum Power Spark Plug: Powerful Perfromance, OE Replacement, RV17PMC4 (Part No.3018)

Platinum Power Spark Plug: Powerful Perfromance, OE Replacement, RV17PMC4

from

$4.99
Champion Platinum Power spark plugs deliver powerful performance. Made from exclusive Heat-Active alloy, a fine-wire center electrode and V-trimmed ground electrode provides sharp spark focus.

Product Features:
  • Heat-Active alloy allows electrodes to reach optimal temperature
  • Platinum tipped center wire resists wear and helps to maintain proper gap spec over life of the plug
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DENSO – Iridium TT Spark Plug: Ultimate Endurance and Power, 0.4mm Iridium Tip, last 100K+ Miles, ITF16TT (Part No.4715)

Iridium TT Spark Plug: Ultimate Endurance and Power, 0.4mm Iridium Tip, last 100K+ Miles, ITF16TT

from

$10.99
Durability of an OE style plug combined with Power & Torque of high performance.

Product Features:
  • 0.4mm Iridium Center Electrode: World’s Smallest Diameter that maximizes firing potential
  • 0.7mm Needle Tip Ground Electrode: Promotes higher spark energy and less heat quenching
  • DENSO Patented Optimized Iridium-Rhodium Alloy Formula: Highest concentration of Iridium vs. competitors for greater durability
  • DENSO Patented 360 degree laser welding process: Ensuring exceptional quality bond and structural strength with the Iridium Center Electrode
  • Durability of an OE style plug combined with Power & Torque of high performance.
  • Withstands temperatures greater than 4000┬░ Fahrenheit
  • Iridium TT
  • Ultimate Endurance and Power: The DENSO Iridium TT Spark Plug features a 0.7mm Iridium Tip, ensuring over 100,000 miles of uncompromised performance.
  • Advanced Twin-Tip Technology: Developed from Original Equipment Specification Super Ignition Plug (SIP) design, combining a Fine Wire Iridium Center Electrode with a Needle Tip Platinum Ground Electrode.
  • Enhanced Fuel Economy and Lower Emissions: Drive around the Earth over 4 times with improved fuel efficiency and reduced emissions.
  • Premium Materials: Features an Iridium Center Electrode Tip and a Tapered Seat Type for optimal performance and durability.
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Motorcraft – Spark Plug: Enhances Durability & Reduces Fuel Consumption (Part No.SP-425)

Spark Plug: Enhances Durability & Reduces Fuel Consumption

from

$2.79
Motorcraft Spark Plugs are original equipment on Ford Motor Company vehicles, engineered to meet strict Ford engineering standards for optimal performance and reliability. These spark plugs are matched to specific engines to provide enhanced durability, eliminate misfires, reduce fuel consumption, and optimize emissions. Resistant to oxidation and arc erosion, they feature a multi-rib insulator to protect against misfires and offer service intervals of up to 100,000 miles. Designed with high-quality materials, Motorcraft Spark Plugs ensure reliable performance for a broad range of applications, including domestic and import cars and trucks of all makes and sizes. Backed by Motorcraft’s Service Parts Warranty, they are an exact fit for Ford, Lincoln, and Mercury vehicles, helping to prevent false check engine lights and providing the same quality as the original components installed during manufacturing.

Product Features:
  • Motorcraft spark plugs are matched to specific engines to provide enhanced durability, eliminate misfires, reduce fuel consumption and optimize emissions.
  • Backed by Motorcraft’s Service Parts Warranty
  • Exact fit for Ford, Lincoln and Mercury vehicles
  • Resistant to oxidation and arc erosion.
  • Multi-rib insulator protects against misfire.
  • Service intervals of up to 100,000 miles.
  • Motorcraft Spark Plugs are designed with high quality materials to provide reliable performance for almost any application.
  • Motorcraft Spark Plugs are what was in the vehicle when it was manufactured
  • Motorcraft ignition components help prevent false check engine lights.
  • Fuel Efficiency: These spark plugs help reduce fuel consumption, optimizing emissions and contributing to a more efficient engine performance.
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NGK – Iridium IX Spark Plug: Single Iridium Fine Wire, UR45IX (Part No.7559)

Iridium IX Spark Plug: Single Iridium Fine Wire, UR45IX

from

$9.99
NGK Iridium IX spark plugs are specifically designed for the performance enthusiast. Iridium IX provides outstanding acceleration, high fuel efficiency and durability. NGK Iridium IX plugs offer extreme ignitability and exceptional anti-fouling. Tapered cut ground electrode provides improved starting, idling and throttle response. The Iridium fine wire center electrode’s durability is six times harder than platinum. Iridium alloy’s extremely high melting point is perfect for today’s engines. For even greater performance consider upgrading to an NGK Ruthenium HX plug.

Product Features:
  • SINGLE IRIDIUM TIP: Fine wire 0.6 millimeter iridium tip center electrode ensures high durability and a consistently stable spark
  • IRIDIUM ALLOY CENTER ELECTRODE: Iridium’s density (6x that of platinum) and extremely high melting point is perfect for modern high efficiency engines
  • TAPERED CUT GROUND ELECTRODE: Reduced quenching design produces outstanding ignitability, improved acceleration, fuel efficiency and durability
  • SOLID COPPER CORE: 98% pure copper core offers superior heat dissipation, conductivity and ultra wide heat ranges
  • TRIVALENT METAL PLATING: Delivers superior anti-corrosion and anti-seizing properties, ensuring ease of installation and removal
  • RECOMMENDED USAGE: Modified or high performance applications, or as an upgrade to OE nickel alloy spark plugs
  • Outstanding Acceleration and High Fuel Efficiency: NGK Iridium IX spark plugs are engineered to deliver superior acceleration and enhanced fuel efficiency, making them ideal for performance enthusiasts.
  • Extreme Ignitability and Anti-Fouling: These spark plugs offer exceptional ignitability and anti-fouling properties, ensuring reliable performance and longevity.
  • High-Performance Upgrade Option: For those seeking even greater performance, NGK recommends upgrading to their Ruthenium HX plugs.
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ACDelco – Double Platinum Spark Plug (Part No.41-816)

Double Platinum Spark Plug

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$9.49
ACDelco Gold (Professional) Double Platinum Spark Plug are a high quality alternative to Original Equipment (OE) parts. With a copper core and double platinum pads on the center electrode, these plugs are designed to deliver long-lasting performance. These premium aftermarket replacement spark plugs are manufactured to meet your expectations for fit, form, and function. ACDelco Gold (Professional) parts are manufactured to meet your expectations for fit, form, and function, making them a smart choice for General Motors vehicles, as well as most makes and models, including special applications. These high-quality parts are backed by General Motors. Some ACDelco Gold parts may have formerly appeared as ACDelco Professional.

Product Features:
  • One-piece, fired-in suppressor seal blends three glass types for a gas-tight seal that helps reduce radio frequency and engine interference, regulate spark plug energy, and protect against compression pressures for long life
  • Double platinum point pad on center and ground electrode offer excellent durability and consistent voltage demands to help reduce wear on ignition system
  • Pure copper core results in cooler electrode temperature for maximized durability and fouling resistance
  • Some ACDelco Gold parts may have formerly appeared as ACDelco Professional
  • Premium aftermarket replacement part
  • Manufactured to meet specifications for fit, form, and function for General Motors vehicles as well as most makes and models
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Autolite Iridium – Iridium XP Finewire Spark Plug: Improved Durability, More Focused Ignition (Part No.XP666)

Iridium XP Finewire Spark Plug: Improved Durability, More Focused Ignition

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$8.99
Our best spark plug! Autolite has over 100 years of engineering experience and has sold over 11 billion plugs. Designed and engineered in the USA, the Autolite Iridium XP spark plugs feature an iridium-enhanced 0.6mm finewire design and patented platinum sidewire technology to provide better overall durability and a more focused ignition for enhanced ignitability and performance. Features double Iridium-enhanced alloy technology center electrode for improved durability and wear resistance.

Product Features:
  • 0.6 mm finewire design improves ignitability
  • Patented V-trimmed platinum sidewire technology resists wear
  • OE equivalent design is engineered for every engine
  • Designed for better overall durability with virtually no gap erosion
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Motorcraft – Spark Plug (Part No.SP-425-X)

Spark Plug

from

$5.29
The Motorcraft Spark Plug is a high-quality replacement spark plug designed to provide reliable performance and long-lasting durability for your vehicle. It features a nickel alloy electrode that provides superior wear resistance and a platinum tip that ensures consistent performance over the life of the plug. The Motorcraft Spark Plug also has a ribbed insulator design that helps prevent misfires and a copper core that provides efficient heat transfer. It is designed to meet or exceed OEM specifications and is compatible with a wide range of vehicles. Whether you’re looking to replace worn-out spark plugs or upgrade to a higher-quality option, the Motorcraft Spark Plug is an excellent choice that will help keep your engine running smoothly and efficiently.
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FAQs for 1978 Mercury Cougar Spark Plugs

What are the most popular Spark Plugs for the 1978 Mercury Cougar?

With 8 brands you can trust, our most popular Spark Plugs for the 1978 Mercury Cougar parts are:

What are the best aftermarket Spark Plugs for the 1978 Mercury Cougar?

See what past customers had to say about our highest-rated Spark Plugs for the 1978 Mercury Cougar:
Copper Spark Plug: Delivers Quick Starts, Good Fuel Economy, Smooth Acceleration
from $3.49
(16)
Copper Spark Plug: Delivers Quick Starts, Good Fuel Economy, Smooth Acceleration
“Good product. Will buy again.”