ACDelco GM Original Equipment 41-602 Spark Plug Review
By: Editorial Team | Last updated: June 11, 2026
The ACDelco GM Original Equipment 41-602 is a conventional spark plug made for specified GM applications and some marine uses. The article information lists a copper core, Black Onyx coating, ribbed suppressor seal, and compact 1.13-ounce build. Buyers should still confirm fitment, gap, and torque specs against the current Amazon listing, the vehicle manual, or the ACDelco catalog before ordering.
Verdict
ACDelco 41-602 Spark Plug: Good OE-Style Choice for the Right GM Engine
This spark plug is best for owners who need the exact ACDelco 41-602 fitment. Its copper-core design supports heat transfer, while the listed corrosion-resistant coating helps in harsh or marine environments. The main caution is compatibility. Spark plugs are engine-specific, so do not buy only by brand name.
Key Specs
| Specification | Detail |
|---|---|
| Brand | ACDelco |
| Product Line | GM Original Equipment |
| Model | 41-602 |
| ASIN | B000C9M90S |
| Spark Plug Type | Conventional spark plug |
| Core Material | Copper core |
| Coating | Black Onyx coating listed in the source article |
| Thread Size | 14mm |
| Hex Size | 5/8 inch |
| Reach | 19mm |
| Listed Dimensions | 3.6 x 0.9 x 0.9 inches |
| Listed Weight | 1.13 ounces |
| Installation Note | Confirm exact gap and torque in the service manual before installation |
What Is This Product?
The ACDelco GM Original Equipment 41-602 is a replacement spark plug for compatible GM engines and some marine applications. It is designed as an OE-style ignition part, not a universal performance upgrade.
The listed design uses a copper core to help transfer heat away from the firing tip. The source article also lists a ribbed suppressor seal, nickel-chrome sheathing, and Black Onyx coating for corrosion resistance.
Who It Is For
- GM owners whose vehicle catalog or service manual calls for ACDelco 41-602 or a compatible part number.
- Marine users who have confirmed this plug is correct for their engine.
- DIY owners who want an OE-style replacement rather than a different plug design.
- Technicians replacing plugs in matched sets during scheduled maintenance.
Who Should Skip It
- Anyone who has not confirmed fitment by engine, model year, and plug specification.
- Drivers looking for a different heat range without checking the ACDelco catalog first.
- Buyers who need a confirmed multi-pack or single-pack count before purchase.
- Owners whose vehicle manual calls for a different plug material, reach, thread size, or gap.
Key Features
Copper Core Design
The copper core is the main functional feature. Copper helps move heat through the plug, which supports stable ignition when the plug is used in the correct engine.
Corrosion-Resistant Finish
The article lists Black Onyx coating and nickel-chrome sheathing. These details matter for engines exposed to moisture, road salt, or marine conditions. Even with corrosion-resistant materials, plugs should still be inspected during routine service.
Ribbed Suppressor Seal
The ribbed suppressor seal is listed as a feature that helps reduce flashover. This supports cleaner ignition performance when the plug, wire, coil, and boot are all in good condition.
OE-Style Fitment
This plug is positioned as a GM Original Equipment part. That makes fitment confirmation more important. Check the current Amazon listing, the ACDelco catalog, or your service manual before buying.
Real-World Use
In normal road use, the 41-602 is aimed at consistent ignition, stable idle, and predictable throttle response in compatible engines. It is not a plug to choose by guesswork. The correct heat range, reach, thread size, and gap all affect performance and engine safety.
For marine use, the listed corrosion-resistant coating is useful, but it does not remove the need for regular inspection. Saltwater exposure, moisture, and long storage periods can still affect threads, terminals, boots, and ignition coils.
The article mentions a possible 0.044-inch factory gap and an 18 lb-ft torque figure. Treat these as checks, not universal rules. Always follow the engine service manual for the final gap and torque spec.
Pros and Cons
Pros
- OE-style ACDelco part for specified GM applications
- Copper core supports heat transfer during normal operation
- Listed Black Onyx coating and nickel-chrome sheathing help with corrosion resistance
- Compact plug with common listed specs, including 14mm thread and 5/8 inch hex
Cons
- Compatibility must be checked carefully before purchase
- The source article mentions possible discontinued status, so sourcing may vary
- Exact gap, torque, and service interval can vary by engine
- No live buyer review themes were verified from the provided HTML alone
Is It Worth the Price?
The ACDelco 41-602 is worth considering if it is the correct plug for your engine and you want an OE-style replacement. The value comes from fitment confidence, copper-core construction, and the listed corrosion-resistant finish.
It is not worth buying if you cannot confirm compatibility. A spark plug with the wrong reach, heat range, or gap can cause poor performance or engine damage. Check the current Amazon page and your service information before ordering.
Alternatives to Consider
These alternatives are listed only for context. Do not treat them as direct replacements unless your vehicle manual or parts catalog confirms compatibility.
- NGK V-Power spark plugs: Common conventional-style plugs available for many applications.
- Champion Copper Plus spark plugs: Another copper-core option used in many older and standard ignition applications.
- Autolite copper spark plugs: A budget-friendly conventional plug line for compatible engines.
Installation and Maintenance Tips
Before installation, confirm the part number, thread size, reach, heat range, gap, and torque spec. Inspect the threads and sealing surface. Replace damaged boots or wires if they show cracking, corrosion, or oil contamination.
The source article lists 14mm thread, 19mm reach, 5/8 inch hex, and 18 lb-ft torque. Use these only as starting information. The engine service manual should control the final installation spec.
For maintenance, inspect plugs during scheduled service or sooner if the engine misfires, idles poorly, loses power, or becomes harder to start. The source article mentions 30,000 miles or yearly service checks, but service intervals vary by engine and operating conditions.
Frequently Asked Questions
Can these spark plugs be used with aftermarket ignition coils?
Yes, if the coil, plug gap, heat range, and engine application match the vehicle specifications. Confirm the ignition setup before installation.
Are other heat ranges available for this exact part?
The 41-602 should be treated as one specific spark plug part number. If you need a different heat range, check the ACDelco catalog or your service manual for the correct alternate part.
Do they come individually packaged or only in multi-packs?
The provided article does not confirm the current package count. Check the live Amazon listing before buying, because sellers may offer single plugs or multi-pack listings.
Are replacement gaps pre-set from the factory?
Many spark plugs are sold pre-gapped, but you should still verify the gap before installation. Shipping and handling can change the electrode gap.
Is there a recommended torque specification for installation?
The source article lists 18 lb-ft and also mentions a typical 13 to 18 lb-ft range for many GM aluminum cylinder heads. Use the vehicle service manual for the exact engine-specific torque spec.
Is this a good choice for marine use?
It may be a good choice only if the marine engine calls for this plug. The listed corrosion-resistant coating helps, but marine engines still need regular inspection because moisture and salt can accelerate wear.
Final Verdict
The ACDelco GM Original Equipment 41-602 spark plug is a sensible OE-style replacement for the right GM or compatible marine application. Its copper core, listed corrosion-resistant finish, and compact design make it practical for routine ignition service.
The main buying rule is simple: verify fitment first. Check the current Amazon listing, service manual, and part catalog before ordering. If the 41-602 is the correct plug for your engine, it is a solid option for dependable replacement service.
