Keeping your 350 Chevy engine running at its peak performance starts with a simple, yet critical component: the spark plug. The right set of plugs can make a significant difference in throttle response, fuel efficiency, and overall engine smoothness. With so many options on the market, from basic copper to advanced iridium, selecting the best one for your specific needs can be a challenge.
This guide is designed to cut through the confusion and present a curated list of the top-performing spark plugs and related ignition components for your small block Chevy. We have compiled a range of products from trusted industry leaders to help you make an informed decision for your next tune-up or performance upgrade.
The Best Spark Plugs for Your 350 Chevy Engine
- NGK # 3186 G-Power Platinum Spark Plugs
- Lucky Seven 10.5mm Spark Plug Wire Set
- NGK 6619 Iridium IX Spark Plug (4 Pack)
- ACDelco 41-962 Professional Platinum Spark Plug
- 4 New NGK V-Power Spark Plugs TR55# 3951
- 6 New NGK IRIDIUM IX Spark Plugs TR55-1IX
- Autolite 3923 Copper Resistor Spark Plugs
- Champion Copper Plus 71 (RC12YC) Spark Plug
- MSD Street Fire 5553 Spark Plug Wire Set
- Bosch 9607 Platinum+2 Spark Plug
NGK # 3186 G-Power Platinum Spark Plugs TR5GP – 8 PCSNEW
The NGK G-Power Platinum spark plugs are an excellent balance of performance and value. They are designed to operate over a much wider heat range than standard plugs, which makes them a reliable choice for a variety of driving conditions, from daily commuting to more demanding use.
This design helps the plug resist carbon buildup and pre-ignition, contributing to a more stable and efficient combustion process. The platinum construction offers a good service life, making these plugs a solid, long-lasting upgrade for your 350 Chevy engine.
10.5mm High Performance Spark Plug Wire Set Fit for HEI BBC SBC 350 454 383 Electronic by Lucky Seven
A complete ignition upgrade involves more than just plugs. The Lucky Seven 10.5mm High Performance Spark Plug Wire Set is engineered to handle the demands of a powerful V8 engine. These wires are built to transfer high-voltage pulses efficiently, ensuring a strong and consistent spark for optimal combustion.
Featuring a high-temperature, 100% pure silicone outer layer and 90-degree boots on both ends, this set is ready for a straightforward installation on HEI systems. It is a universal fit for small block and big block Chevy engines, including the 350, making it a versatile and durable component for your ignition system.
NGK 6619 Iridium IX Spark Plug LFR6AIX-11 (4 Pack)
For those seeking high-performance ignition, the NGK Iridium IX spark plugs are a top contender. Iridium is one of the hardest and most durable metals used in spark plugs, allowing for a finer center electrode that requires less voltage to spark. This can lead to improved throttle response and more complete combustion.
This four-pack offers a convenient way to get genuine NGK quality for your engine. The advanced design is built for longevity and consistent performance, making it a favorite for enthusiasts who want to maximize their engine’s potential.
ACDelco 41-962 Professional Platinum Spark Plug
ACDelco Professional Platinum spark plugs are a trusted choice for a reliable OEM-style replacement. They feature a double platinum design, with pads on both the center and ground electrode, which helps minimize electrode wear and maintains a consistent spark gap for a long service life.
The pure copper core allows for superior heat dissipation, which helps prevent fouling and promotes a wider heat range. The one-piece, fired-in suppressor seal ensures a gas-tight fit, reducing the chance of combustion gas leakage and contributing to overall engine efficiency.
4 New NGK V-Power Spark Plugs TR55# 3951
The NGK V-Power spark plug is a fundamental and highly effective option for many 350 Chevy engines. Known for their quality and reliability, these plugs are often specified as original equipment by vehicle manufacturers. The unique V-groove design of the center electrode concentrates the spark, encouraging a more robust flame kernel for improved combustion.
This design can contribute to better fuel efficiency and smoother idling. As a pack of four, they are an excellent choice for a standard tune-up, offering the performance and durability you expect from a leading brand in ignition technology.
6 New NGK IRIDIUM IX Spark Plugs TR55-1IX # 7316
This six-pack of NGK Iridium IX plugs provides a partial set for engines that require this specific high-performance plug. Like their counterpart, these plugs utilize a fine-wire iridium tip for superior ignitability and long-term durability. The trivalent metal plating on the shell offers superior anti-corrosion and anti-seizing properties.
This is an ideal option if you are looking for the benefits of iridium technology and need a specific quantity for your vehicle. The advanced construction helps ensure a consistently strong spark, which is vital for maintaining engine power and efficiency.
Autolite 3923 Copper Resistor Automotive Replacement Spark Plugs
Autolite Copper Resistor spark plugs are a classic, cost-effective choice for many applications. The full copper core center electrode provides excellent thermal conductivity, which allows the plug to manage heat effectively across a wide range of engine operations.
These plugs feature a copper-glass seal that bonds the internal components, creating a leak-proof design for long-lasting durability. For a standard replacement on a stock engine or for vintage vehicles, these copper plugs offer dependable performance and reliable operation.
Champion Copper Plus 71 (RC12YC) Spark Plug
The Champion Copper Plus spark plug is another reliable copper-core option known for its durable performance. The copper core allows for precise heat range control, which contributes to a longer service life and consistent operation. The design also includes features to inhibit corrosion, protecting the plug from the harsh environment inside the engine bay.
While often associated with specific imports, it’s important to verify the correct heat range and application for your 350 Chevy. When applicable, this plug provides a solid, traditional choice for dependable ignition.
MSD Street Fire 5553 Spark Plug Wire Set
From a renowned name in performance ignition, the MSD Street Fire Spark Plug Wire Set is built to deliver. The 8mm wires feature a silicone and synthetic jacket that is engineered to resist high temperatures and abrasion, ensuring longevity even in a crowded engine compartment.
The kit includes a variety of wire lengths to fit a V8 configuration neatly, and the heavy-duty terminals provide a secure connection to both the plugs and the distributor. This set is an excellent way to add both performance and a clean, professional look to your engine bay.
Bosch 9607 Platinum+2 Spark Plug
Bosch Platinum+2 spark plugs feature a unique design with two fine-wire platinum electrodes—a center electrode and a ground electrode. This double-platinum system is engineered to provide a consistent and reliable spark, as the electrical charge can choose the path of least resistance between the two points.
This design aims to promote efficient combustion and can contribute to a smooth engine run. The surface air gap technology helps burn off deposits, which can help maintain performance over the plug’s lifespan. It’s a technologically advanced option for those seeking a high-quality platinum plug.
Buying Guide: How to Pick the Right Spark Plugs for Your 350 Chevy
Choosing the best spark plugs for your 350 Chevy engine isn’t just about grabbing the first box off the shelf. It’s about matching the plug to your engine’s specific setup and how you use your vehicle. I’ve learned that getting this right makes a huge difference in performance, fuel economy, and how smoothly the engine runs. Let’s walk through the key things I always consider.
First up is the heat range. This is probably the most important factor. The heat range refers to a spark plug’s ability to dissipate heat from its firing tip. A plug that runs too hot can cause pre-ignition (knocking), while one that runs too cold will foul up with carbon deposits. For a mostly stock 350 used for daily driving, a standard heat range is perfect. But if you’ve added performance parts like a supercharger or you’re often towing heavy loads, you’ll likely need a colder plug to handle the extra cylinder temperatures. Conversely, if your engine burns a little oil or is used mostly for short trips, a slightly hotter plug can help burn off deposits.
Next, you need to decide on the electrode material. This directly affects longevity and performance. Traditional copper core plugs are great conductors and inexpensive, but they wear out faster, needing replacement every 20,000 miles or so. Platinum plugs last longer, typically around 60,000 miles, thanks to their harder electrode material. Iridium plugs are the top-tier option; they have a super-fine center electrode that requires less voltage to create a spark and can last over 100,000 miles. For a high-performance 350 Chevy, the efficiency of an iridium plug is often worth the extra cost.
You also have to think about the plug’s design. Are you looking at a standard single-ground electrode plug, or a performance-oriented multi-ground electrode design? Some folks swear by the multiple electrodes for a more consistent spark, while others prefer designs with a tapered cut ground electrode for better flame kernel propagation. For a street-driven 350, the difference might be subtle, but it’s a consideration for squeezing out every bit of power.
Finally, always double-check the thread reach and gap. Using a plug that’s too long can physically contact the piston, causing catastrophic damage. One that’s too short can lead to poor combustion and carbon buildup in the threads. Most 350 small blocks use a 14mm thread with a 3/4″ reach and a 5/8″ hex, but it’s always smart to confirm with your engine’s specifications or pull an old plug to compare. While many plugs come pre-gapped, it’s a good habit I have to check the gap with a feeler gauge before installation, especially if you’ve upgraded your ignition system.
FAQ
What is the factory heat range for a stock 350 Chevy?
For a classic, stock 350 cubic inch Chevy engine, the original equipment manufacturer (OEM) heat range was typically an AC Delco R45TS or equivalent, which is a standard heat range copper core plug. This is a great starting point if your engine is unmodified and used for normal driving. If you’re looking at our list of the 10 Best Spark Plugs for 350 Chevy Engine: A 2025 Review Guide, you’ll find several options that match or improve upon this specification.
Should I use platinum or iridium spark plugs in my 350?
This comes down to your goals and budget. Platinum plugs are a solid upgrade from copper, offering better longevity—think 60,000 miles versus 20,000. Iridium plugs are the premium choice. Their fine-wire center electrode allows for a stronger, more efficient spark and they can often last over 100,000 miles. For a daily driver where you just want to “set it and forget it,” iridium is fantastic. For a high-performance build where spark efficiency is critical, iridium is usually the best bet.
How often should I change the spark plugs in my 350?
The change interval depends entirely on the type of plug you use. For traditional copper plugs, plan on a change every 20,000 to 30,000 miles. Platinum plugs can usually go 60,000 miles, and iridium plugs can often last 80,000 to 100,000 miles. However, if you notice symptoms like rough idling, misfires, a loss of power, or reduced fuel economy, it’s a good idea to check your plugs regardless of the mileage.
What should I gap my spark plugs to?
The correct gap for a 350 Chevy can vary based on the year and ignition system. For older points-style ignition systems, a gap of 0.035 inches is common. For most HEI (High Energy Ignition) systems, a wider gap of 0.045 inches is typical. Always consult your vehicle’s service manual or the specifications for your specific distributor or ignition coil to be sure. Even plugs advertised as “pre-gapped” should be checked with a feeler gauge, as they can be knocked out of spec during shipping.
Can the wrong spark plugs damage my engine?
Yes, using the wrong spark plugs can absolutely cause problems. The most serious risk is using a plug with too long of a thread reach (length). This can cause the electrodes to physically contact the piston, leading to severe engine damage. A plug with an incorrect heat range can also cause issues; a plug that’s too hot can lead to pre-ignition and detonation, which can burn pistons or blow head gaskets. A plug that’s too cold will foul up and cause misfires.