Best Spark Plugs for 602 Crate Motor

When I first got my hands on my 602 crate engine, I quickly realized that cheaping out on ignition components wasn’t an option. Reliability is everything when you’re running sealed engines, and choosing the best spark plugs for a 602 crate motor is critical for consistent performance and avoiding mid-race misfires. We’ve spent time looking at various high-quality options, focusing primarily on copper core plugs known to handle the heat and provide that reliable spark needed for optimal performance and efficiency, whether you’re on the street or the track.

IMAGE	PRODUCT NAME	AMAZON LINK
	ACDelco GM Original Equipment 41-602 (19354429)…	View on Amazon
	OEM Champion Spark Plug for Autolite 3924, 3926, 5503,…	View on Amazon
	OEM (Pack of 2) Champion Spark Plugs for Autolite 3924,…	View on Amazon
	2Pcs CNPAPC Upgrade Double Iridium IX Spark Plugs DCPR7EIX…	View on Amazon
	E3 Spark Plugs E3.36 Premium Powersports Spark Plug for…	View on Amazon
	Stens 131-039 PK2 Torch Spark Plugs F6RTC	View on Amazon
	OEM (Pack of 4) Champion Spark Plugs for Autolite 3924,…	View on Amazon

ACDelco GM Original Equipment 41-602 (19354429) Conventional Spark Plug

The ACDelco 41-602 is a staple for anyone running GM spec engines. This plug is designed to meet the exact requirements of your engine, offering the kind of dependable, factory-level performance you need, especially in a sealed environment like the 602. The copper core ensures excellent heat transfer, which is crucial for preventing pre-ignition under heavy load, and its overall construction is robust, making it a trustworthy choice right out of the box.

Key features that stand out:
– Black Onyx coating helps reduce corrosion for extended plug life.
– 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 the center electrode.

Pros:
– Excellent heat management crucial for crate motors.
– OEM reliability and fitment.
– Great conductivity thanks to the copper core.

Cons:
– Traditional copper core requires more frequent replacement than iridium.

Best for:
Spec racing series requiring OEM-style or copper-core plugs where consistency is key.

Expert Opinion: This is the baseline of reliability. While it doesn’t offer fancy materials, the copper conductivity and GM engineering ensure you get the maximum spark energy needed for consistent torque in high-rev applications.

OEM Champion Spark Plug for Autolite 3924, 3926, 5503, 602, AP3924, XS3924 Engines

Champion is a legacy name in racing, and this specific OEM replacement plug is often cross-referenced as the standard choice for the 602 crate platform (often replacing common Autolite numbers). This is a single-unit purchase, ideal if you are replacing just one plug, or want to verify the correct heat range before committing to a full set. It’s engineered for reliable starts and steady combustion, providing solid foundational performance without unnecessary frills.

Key features that stand out:
– Direct OEM replacement for several common plug numbers associated with the 602 platform.
– Reliable construction geared toward consistent ignition performance.
– Specs match original equipment for accurate heat range.
– Easy identification and confirmation using OEM part numbers provided.

Pros:
– Highly compatible with the 602 motor’s heat requirements.
– Trusted Champion reliability.
– Cost-effective single-unit purchase.

Cons:
– Requires careful verification of specific OEM numbers before purchase.

Best for:
Budget-conscious racers or mechanics needing to replace a single fouled plug immediately.

Expert Opinion: Always confirm the required OEM part number, as the 602 platform can be sensitive to subtle differences in reach and heat range. If the cross-reference is correct, this is a solid, economical performer.

OEM (Pack of 2) Champion Spark Plugs for Autolite 3924, 3926, 5503, 602, AP3924

This is the exact same high-quality OEM Champion spark plug as the previous entry, but packaged conveniently in a pair. For those who like to keep a few spare plugs on hand or are tackling a smaller maintenance job, a two-pack offers better value than buying singles. These plugs maintain the precise specifications needed for the 602 and related small-block applications, ensuring optimal burn efficiency and power delivery.

Key features that stand out:
– Includes two reliable OEM Champion plugs at a convenient price point.
– Engineered to match precise OEM specs for heat and fitment.
– Directly cross-references with common Autolite 3924/3926 plugs often used in this motor.

Pros:
– Excellent value when buying in small quantities.
– Reliable ignition performance.
– Ideal for keeping spares in the trailer or garage.

Cons:
– You will need three more packs to complete a full 8-cylinder motor change.

Best for:
Keeping pit-side spares or for two-cylinder applications (like motorcycle engine swaps using a similar design).

Expert Opinion: Two-packs are great for targeted maintenance, but if you’re doing a full engine refresh, buying the 8-pack equivalent (or the 4-pack reviewed later) will usually save you money per plug.

2Pcs CNPAPC Upgrade Double Iridium IX Spark Plugs DCPR7EIX #3144#6046#97637 for 1999-2016 Harley Davidson Twin Cam…

While typically geared toward motorcycles, these Double Iridium plugs represent a significant performance and durability upgrade over standard copper. If you are running a modified 602 crate motor for a street rod or non-spec application where longevity and high-energy spark are desired, iridium can be a great choice. Double Iridium offers superior resistance to wear and heat compared to single-platinum or standard copper.

Key features that stand out:
– SUPER POWER: Double Iridium IX Spark Plugs designed for extreme ignitability and improved throttle response.
– LONGER LIFE: Fine Double Iridium tip ensures stability and high durability, perfect for high-tech, high-performance engines.
– MORE FUEL EFFICIENT: Reduces flameout phenomenon, keeping the engine in better running condition for lower fuel consumption.
– Trivalent Metal Plating provides outstanding acceleration and high durability.

Pros:
– Exceptional service life (less maintenance).
– Extremely stable, high-energy spark.
– Improved performance and fuel efficiency potential.

Cons:
– Often outside the rules for sealed 602 crate racing engines.

Best for:
Modified 602 engines in non-spec environments (street rods, marine, or custom builds) where plug longevity is paramount.

Expert Opinion: Iridium plugs are fantastic for extending maintenance intervals, but remember they are generally a colder plug and may not be the standard heat range required for stock 602 specifications. Always verify fitment and heat range before installation.

E3 Spark Plugs E3.36 Premium Powersports Spark Plug for V-Twin Motorcycles, Harley Davidson Engines, and Other High-Performance Powersport Vehicles, Pack of 1

E3 plugs stand out due to their unique DiamondFIRE electrode design, which promotes a faster, more turbulent flame kernel. This can result in a more complete burn, potentially boosting power and efficiency. While listed for powersports, the E3.36 can be cross-referenced for small-block applications where users are looking for maximum combustion efficiency. This design focuses on enhancing performance metrics like horsepower and fuel economy.

Key features that stand out:
– DIAMONDFIRE TECHNOLOGY: Patented edge-to-edge electrode delivers a faster, more complete burn.
– ENHANCED PERFORMANCE: Designed to improve power by up to 12% and fuel efficiency by up to 13%.
– LOWER EMISSIONS: The more complete burn helps reduce CO and hydrocarbon emissions significantly.
– Universal fitment that crosses over to various high-performance vehicles.

Pros:
– Unique electrode design maximizes combustion.
– Claimed benefits in power and fuel economy.
– Helps minimize carbon buildup.

Cons:
– Performance benefits are highly variable depending on engine tuning and application.

Best for:
High-performance hobbyists looking to maximize the combustion efficiency of their 602 street engine.

Expert Opinion: E3 plugs have a dedicated following. Their greatest benefit is usually seen in engines that previously suffered from poor combustion. For a finely tuned crate motor, the gains might be smaller, but the consistent, clean spark is certainly beneficial.

Stens 131-039 PK2 Torch Spark Plugs F6RTC

Stens is known for reliable replacement parts, and these Torch brand spark plugs are commonly used as OEM replacements across many small engine and powersport applications, often cross-referencing to common copper plugs suitable for the 602 motor’s requirements. Sold in a convenient two-pack, they represent a straightforward, reliable, and economical solution. The F6RTC designation generally indicates a specific heat range suitable for robust, air-cooled, or moderate-duty applications, making it a reliable backup or maintenance option.

Key features that stand out:
– Genuine Stens replacement part ensuring quality control.
– F6RTC designation indicates a common and reliable heat range.
– Bulk packed for economical purchasing.
– Direct replacement for various small engine applications.

Pros:
– Highly economical choice.
– Reliable maintenance solution.
– Good for general-purpose applications.

Cons:
– May lack the specialized anti-corrosion features of higher-end plugs.

Best for:
Mechanics or users needing a reliable, budget-friendly bulk replacement plug for general maintenance purposes.

Expert Opinion: When running a crate motor, sticking to recognized brands and heat ranges (like the traditional 3924 or 41-602 equivalents) is usually best practice. The Stens/Torch cross-reference provides a reliable, budget alternative if the exact OEM part is unavailable.

OEM (Pack of 4) Champion Spark Plugs for Autolite 3924, 3926, 5503, 602, AP3924

If you’re running the 602 on a V8 platform, this 4-pack of OEM Champion plugs is the perfect mid-size maintenance kit. This package provides half the necessary plugs for a full tune-up or a substantial number of spares. Like the 1-pack and 2-pack, these plugs offer the foundational copper-core reliability that many crate motor builders rely on, ensuring excellent conductivity and proper heat dissipation tailored for these specific engine requirements.

Key features that stand out:
– Convenient 4-pack for half a V8 motor replacement or ample spares.
– OEM Champion quality guarantees reliable fit and performance.
– Direct cross-reference to standard 602-friendly plugs like the Autolite 3924.

Pros:
– Great bulk pricing compared to singles.
– Essential for regular maintenance rotation.
– Dependable copper core performance.

Cons:
– You will need two of these packs for a complete engine change.

Best for:
Users who conduct partial plug changes frequently or prefer to buy in manageable quantities.

Expert Opinion: For the 602, you will likely be changing plugs more frequently than a street engine, especially if running rich. Buying in 4-packs is a smart way to manage inventory without committing to a massive 20-pack purchase.

Comparison Insights: Choosing the Right Plug Material

When selecting spark plugs for the 602 crate engine, the choice usually boils down to material: traditional copper, or advanced Iridium/Performance plugs.

For spec racing or sealed engine rules, you almost always need to stick with standard copper core plugs, like the ACDelco 41-602 or the Champion OEM cross-references. Copper offers superior electrical conductivity compared to nickel or platinum alloys, which results in a high-energy spark ideal for a short, intense race life. The downside is that copper wears faster, necessitating frequent plug changes—every 5 to 10 nights of racing.

If you are running a 602-based street engine or a modified build without stringent sealed rules, advanced plugs become viable. Double Iridium plugs (like the CNPAPC) offer vastly improved longevity and a highly stable spark. This means you won’t have to change them nearly as often, but they may slightly compromise the raw, immediate conductivity of copper. The E3 plugs, with their unique electrode design, are focused on maximizing the burn and improving efficiency, which is a great goal for daily driving or sustained runs.

Ultimately, correct heat range is non-negotiable regardless of the material. Using a plug that is too hot will lead to disastrous pre-ignition in the 602, while one that is too cold will foul out easily. Always stick to the factory-recommended heat range equivalents (like the 3924 or DCPR7EIX equivalent).

Final Verdict

Making the best selection for your 602 crate motor depends entirely on your application and rulebook:

The Spec Racer’s Champion: If you are strictly adhering to rules for a sealed crate motor, the ACDelco GM Original Equipment 41-602 is our top recommendation. It provides the OEM specifications, reliable copper conductivity, and the precise heat range required to keep your motor legal and performing consistently under harsh track conditions.

Best for Longevity and Modified Street Use: For those running a 602 derivative on the street and prioritizing long-term durability, the 2Pcs CNPAPC Upgrade Double Iridium IX Spark Plugs offer incredible stability and lifespan, minimizing the need for constant maintenance.

The Practical, Budget Pick: For excellent value when performing routine maintenance, the OEM (Pack of 4) Champion Spark Plugs is the most practical choice. It offers the widely accepted, reliable cross-reference plug in a convenient quantity for V8 engine upkeep.

FAQs About the Best Spark Plugs for a 602 Crate Motor

Q1: What is the recommended spark plug gap for a 602 crate motor?

The standard recommended plug gap for a stock 602 crate motor is usually around 0.035 inches. However, since these motors often run sealed ignition systems, it’s always best practice to consult your specific engine builder or racing organization’s documentation, as slight variations might be allowed or required based on fuel and altitude.

Q2: Should I use copper, platinum, or iridium spark plugs in a sealed 602 engine?

For performance consistency in sealed engines, copper core spark plugs are overwhelmingly preferred. They offer the lowest resistance and highest conductivity, delivering maximum spark energy. Iridium and platinum plugs are durable and last longer but their reduced conductivity makes them less ideal for the rapid, high-energy demands of spec racing compared to traditional copper.

Q3: How often should I change the spark plugs in my 602 crate motor?

If you are running the motor competitively in a racing environment, spark plugs should be checked frequently and often replaced after every 5 to 10 race nights. Crate motors typically run high compression and specific fuel mixtures that can rapidly degrade or foul standard copper plugs. Regular inspection is key to monitor the engine’s tuning health.

Q4: Are the Autolite 3924/3926 plugs interchangeable with the OEM Champion plugs?

Yes, the Autolite 3924 and 3926 plugs are widely recognized as equivalent and are frequently cross-referenced with the OEM Champion plugs mentioned in this article. They represent the correct heat range and physical specifications required for the 602 platform, making them highly reliable substitutes.

Q5: Can I use a high-performance spark plug like E3 in my 602 crate motor?

While plugs like the E3 (with its unique electrode design) can offer combustion efficiency improvements, they may not be allowed under the sealed engine rules set by your particular racing association. Always check the official rulebook before installing any non-standard ignition components. For street use, performance plugs are generally acceptable.

Q6: What happens if I use a spark plug with the wrong heat range?

Using a spark plug that is too “hot” (meaning it retains heat longer) can lead to pre-ignition or detonation, seriously damaging the pistons and valves in the 602 motor. Conversely, a plug that is too “cold” (sheds heat too quickly) will tend to foul easily, leading to misfires and poor performance, especially at lower RPMs. Always match the recommended heat range exactly.