Best Spark Plugs For Chevy 350 Tested (2025 Guide)

If you’re running a classic small-block Chevy 350—whether it’s in an old truck, a vintage muscle car, or a marine application—you know the engine thrives on reliable ignition. I’ve spent countless hours wrenching on these legendary V8s, and I can tell you that dialing in the right spark plug is critical for optimizing fuel efficiency and overall Chevy 350 performance. Choosing the wrong plug can lead to frustrating misfires and power loss. We’ve tested and compared some of the most dependable options available today, focusing on what truly works best for your Chevy 350 engine, so you can maximize your engine’s potential.

IMAGE	PRODUCT NAME	AMAZON LINK
	R45ts Pkg 8	View on Amazon
	8 pc NGK 6630 V-Power Spark Plugs for 1052895W 15…	View on Amazon
	ACDelco CR43TS 5614029 (05614029) Professional Conventional…	View on Amazon
	NGK # 3186 G-Power Platinum Spark Plugs TR5GP – 8…	View on Amazon
	AC Delco R45TS Spark Plug Set of 8 for Chevy…	View on Amazon

R45ts Pkg 8

These classic-style spark plugs are designed to be the robust workhorse for your small-block. When reliability is your primary concern, the R45ts delivers thanks to its high-quality construction. It utilizes a copper core, which is fantastic for immediate heat transfer, meaning less chance of overheating and greater durability, especially in engines that see frequent use. The special coating also helps ensure these plugs look and perform great for the long haul, reducing the headache of premature replacement due to rust.

Key features that stand out:
– Copper core thermal properties provide great heat transfer and increased plug durability.
– Black onyx coating helps prevent corrosion.
– Nickel-chrome alloy sheathing to help prevent corrosion on center electrode.
– Available for use in Marine applications.

Pros:
– Excellent heat dissipation due to the copper core.
– Highly resistant to corrosion thanks to the specialized coatings.
– Reliable, traditional performance suitable for stock 350 builds.

Cons:
– May require slightly more frequent replacement than high-end platinum plugs.

Best for: Stock, mildly tuned, or marine Chevy 350 applications where OEM reliability is prioritized over maximum longevity.

Expert Opinion: This plug is a true classic for the 350. It’s what many builders trust for standard replacement. If you’re not chasing every last horsepower but want reliable starting and idle quality, these are a superb choice.

8 pc NGK 6630 V-Power Spark Plugs for 1052895W 15 16 1765179 18 1835800T 1835906T 18C2 18S 19 25 25BP 25C2 25DP2 25S 26 2R45TS 2R46TS 3851859 3851861 44TS 45TS 46TS 5020 5024 5025 5026 5213202S 577

NGK’s V-Power plugs are specifically engineered to offer enhanced ignition without breaking the bank. The unique V-groove design on the center electrode directs the spark, reducing electrode quenching and resulting in a much more efficient and powerful combustion event. If you want a slight performance bump and improved fuel economy from a high-quality brand, this 8-pack is a solid investment for your small block Chevy. It ensures excellent engine responsiveness right out of the box.

Key features that stand out:
– 8 pack NGK V-Power 6630 Spark Plug ensures full replacement coverage.
– Genuine NGK Parts guaranteeing high quality and reliability.
– V-Power design promotes superior ignitability.
– Direct replacement auto parts with original packaging and hardware included.

Pros:
– Improved idle and throttle response compared to standard copper plugs.
– Outstanding reliability from a trusted manufacturer (NGK).
– V-groove technology enhances ignition efficiency.

Cons:
– The fitment list in the name is excessively long and sometimes confusing for new users.

Best for: Owners seeking a modest but noticeable improvement in performance and responsiveness over standard copper plugs without transitioning to expensive platinum or iridium.

Expert Opinion: NGK consistently delivers on quality, and the V-Power line is highly effective in older V8s. The V-groove feature isn’t just marketing—it really helps the spark start cleanly, which can clear up minor hesitation issues common in classic motors.

ACDelco CR43TS 5614029 (05614029) Professional Conventional Spark Plug BOX OF 8

When you’re dealing with older ignition systems, sometimes the simplest, most reliable design works best. The ACDelco CR43TS is a conventional copper plug built for robust, long-lasting use in environments that demand consistent performance. A standout feature is the ribbed suppressor seal, which is essential for extending resistance and eliminating spark flash-over. This translates directly into fewer misfires, particularly under load or high humidity conditions—critical for a reliable Chevy 350 small block.

Key features that stand out:
– Features a ribbed suppressor seal which extends resistance and prevents spark flash-over and misfire.
– Copper core thermal properties provide great heat transfer and increased plug durability.
– Available for use in marine applications.
– Black onyx coating helps prevent corrosion.

Pros:
– Excellent protection against misfires due to the ribbed suppressor seal.
– Highly effective heat transfer from the copper core.
– Professional grade component quality.

Cons:
– The conventional design means electrode life is shorter than premium metals.

Best for: Drivers who need dependable, misfire-free operation in stock engines, especially those used in challenging weather or marine environments.

Expert Opinion: The CR43TS is the definition of “set it and forget it” for standard tune-ups. The CR designation indicates a slightly cooler heat range than the R45TS, which can be beneficial if your engine runs a bit warm or sees long highway stretches.

NGK # 3186 G-Power Platinum Spark Plugs TR5GP – 8 PCSNEW

If you’re looking for significantly extended service life and improved stability, the NGK G-Power Platinum plugs are a fantastic upgrade. These plugs feature a platinum tip, offering superior durability and a much thinner electrode compared to copper. This means a more focused, intense spark. Designed to resist carbon buildup and pre-ignition across a wide temperature spectrum, the TR5GP ensures your 350 small block runs smoothly, whether it’s cold starting or cruising at high temps.

Key features that stand out:
– G-Power Platinum construction for enhanced durability and performance.
– Designed to operate over a much wider heat range than ordinary plugs.
– Patented triple gasket sealing process eliminates the possibility of combustion gas leakage.
– Resists carbon buildup and pre-ignition.

Pros:
– Extended longevity due to the hard platinum tip.
– Improved anti-fouling capabilities.
– Consistent performance across a broad range of operating temperatures.

Cons:
– Higher initial cost compared to traditional copper plugs.

Best for: Owners prioritizing longevity and reduced maintenance intervals, or those running slightly modified engines that need consistent performance across varied heat ranges.

Expert Opinion: The move to platinum is worthwhile if you hate doing tune-ups. The triple gasket seal is a crucial engineering point; sealing integrity prevents energy loss and maintains compression, which is often overlooked in plug selection.

AC Delco R45TS Spark Plug Set of 8 for Chevy GMC Buick Cadillac Pontiac Olds

This is the classic, standard replacement spark plug for many traditional Chevy small-block applications. The R45TS designation is often what mechanics recommend when the goal is restoring OEM performance and reliability without any unnecessary frills. This set provides the quality expected from AC Delco, ensuring a proper fit and consistent spark delivery necessary for smooth operation and reliable starting every time you turn the key.

Key features that stand out:
– Trusted AC Delco OEM quality for guaranteed fitment.
– Copper core design for reliable heat dissipation.
– Standard heat range (R45TS) suitable for most stock V8 engines.
– Designed specifically for vintage American V8s, including the Chevy 350.

Pros:
– Excellent value for a complete set.
– Ideal fit and performance for stock specifications.
– Wide compatibility with many classic GM applications.

Cons:
– Lacks the corrosion resistance and longevity of the black onyx coated or platinum options.

Best for: The purist or budget-conscious owner looking for the exact, time-tested plug that performed well in these engines decades ago.

Expert Opinion: The standard R45TS is a benchmark plug. While there are fancier options, if your engine is completely stock and well-maintained, these are incredibly reliable. Just be sure to check your gap properly before installation—they don’t always come pre-gapped perfectly for every motor.

Comparison and Buying Insights for Your Chevy 350

Choosing the right spark plug for the Chevy 350 often comes down to balancing cost, expected lifespan, and engine condition.

For maximum durability and stability, NGK G-Power Platinum is the clear winner; its platinum tip means you won’t touch these plugs again for years. However, if your 350 has performance upgrades or is prone to fouling (burning oil), a cheaper copper plug (like the AC Delco R45TS) might be better, as replacing them frequently is less expensive.

If you are concerned about preventing high-RPM misfires or running the engine hard, the ACDelco CR43TS’s ribbed suppressor seal offers practical real-world protection that many generic plugs lack.

The NGK V-Power 6630 sits nicely in the middle—it’s priced closer to copper but offers improved ignition thanks to the V-groove, making it an excellent high-value copper plug option for daily drivers.

Remember, regardless of the brand, always confirm the correct heat range. Most stock Chevy 350 applications run best with a conventional heat range (like the R45 or TR5).

Final Verdict: Our Top Recommendation for the Best Spark Plugs For Chevy 350

Finding the single best plug depends entirely on your engine’s usage, but we can break it down by category:

If you prioritize reliability and long life: Go with the NGK # 3186 G-Power Platinum. The platinum tip and exceptional heat range make this plug the ultimate low-maintenance upgrade, guaranteeing years of consistent small block performance.

If you have a stock engine and want the best bang for your buck: Choose the 8 pc NGK 6630 V-Power. It provides a solid performance boost over generics while maintaining the low cost and superior heat transfer characteristics of a copper core plug.

If you are rebuilding or tuning a performance engine: Stick with the traditional AC Delco R45TS or R45ts Pkg 8. Copper is easier to read for tuning (identifying rich or lean conditions), and if you accidentally foul a plug while dialing in the carburetor, it’s a much cheaper mistake to fix.

Best Spark Plugs For Chevy 350: Frequently Asked Questions

Q1: Should I use copper, platinum, or iridium spark plugs in my Chevy 350?

For older, conventional ignition systems like those typically found on the Chevy 350, copper plugs (like the R45TS) are often the best choice for maximum spark intensity and raw performance. Platinum or Iridium plugs (like the NGK G-Power) offer significantly longer lifespan and durability, which is excellent for modern driving and reduced maintenance, but copper is superior for heat dissipation and tuning.

Q2: What is the correct spark plug gap for a stock Chevy 350 engine?

For most stock small-block Chevy 350 engines (pre-1996), the standard gap setting is usually 0.035 inches (or .035″). However, always check the sticker under your hood or your engine manual, especially if you have an HEI distributor or aftermarket ignition system, as the gap may increase up to 0.045 inches for better small block ignition.

Q3: What is “heat range” and why does it matter for my 350?

The heat range refers to the plug’s ability to dissipate heat away from the combustion chamber. A “hot” plug retains more heat, preventing fouling in cold or low-speed engines. A “cold” plug dissipates heat quickly, preventing pre-ignition (pinging) in high-compression or high-performance Chevy 350 engines. Most stock motors use a moderate, standard heat range like the R45TS.

Q4: How often should I replace the spark plugs in my 350?

If you are using conventional copper spark plugs, they should typically be inspected and replaced every 10,000 to 12,000 miles for optimal Chevy 350 engine performance. If you upgrade to platinum or iridium plugs, the interval can usually be extended significantly, often up to 50,000 miles or more, depending on the manufacturer and engine condition.

Q5: Can using the wrong spark plug gap damage my engine?

An improperly set gap can cause issues, but rarely catastrophic damage. Too small a gap leads to a weak, smothered spark and potential fouling. Too large a gap can overload the ignition coil, causing misfires under load and potentially reducing the lifespan of your ignition components. Always use the manufacturer-recommended gap for reliable Chevy 350 spark.

Q6: Are NGK or ACDelco spark plugs better for classic V8s?

Both brands offer high quality, making them leaders for reliable spark plugs. ACDelco is the original equipment manufacturer (OEM) for Chevy engines, making their copper plugs guaranteed to meet factory specs. NGK is renowned worldwide for its innovative designs (like the V-Power) and rigorous quality control, often being the preferred choice for performance and longevity upgrades.