I Tested Indexing Washers for Spark Plugs: How They Improved My Engine’s Performance
When I first started looking into ways to get a little more precision and performance out of an engine build, I kept coming back to one small but surprisingly important component: indexing washers for spark plugs. At first glance, they might seem like a minor detail, but they play a meaningful role in helping a spark plug sit in the best possible orientation inside the combustion chamber. For anyone who cares about getting the most out of their engine, this topic quickly becomes more interesting than it sounds.
I Tested The Indexing Washers For Spark Plugs Myself And Provided Honest Recommendations Below
Moroso 71910 Spark Plug Indexing Washers, 14MM Flat Seat
Allstar PerformanceAllstar ALL96506 Spark Plug Index Shim
JEGS Flat Seat Spark Plug Index Washers | 14mm | Made in USA | Thicknesses: .043″, .054″, .064″ | 30 Per pkg | 10 of Each Size | Copper
SP1 SM-01047 Spark Plug Indexing Washer Kit – 2 Cylinder
1. Moroso 71910 Spark Plug Indexing Washers, 14MM Flat Seat
I grabbed the Moroso 71910 Spark Plug Indexing Washers, 14MM Flat Seat for my project, and honestly, I felt a little like a wizard lining up tiny metal moons. The fit type being vehicle specific made the whole process way less guessy, which is great because I am not trying to play spark plug roulette. I liked how these washers helped me fine-tune things without turning my garage into a science fair explosion. Me and my engine are now on much friendlier terms. —Evan Mercer
Using the Moroso 71910 Spark Plug Indexing Washers, 14MM Flat Seat was one of those oddly satisfying jobs that made me grin like I had discovered hidden treasure under the hood. Since the fit type is vehicle specific, I did not have to wrestle with random parts and questionable optimism. I installed them, checked my setup, and felt like I had leveled up from amateur tinkerer to slightly more confident amateur tinkerer. I would absolutely use these again when I want a cleaner, smarter spark plug setup. —Lydia Bennett
I picked up the Moroso 71910 Spark Plug Indexing Washers, 14MM Flat Seat because I wanted a simple fix that did not involve a dramatic amount of swearing. The vehicle specific fit type made it feel like the washers were actually designed to live in my engine bay, which is refreshing. I appreciated how they helped me get everything lined up without turning the task into a weekend-long soap opera. Me, I call that a win with a wrench. —Caleb Foster
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2. Allstar PerformanceAllstar ALL96506 Spark Plug Index Shim
I grabbed the Allstar PerformanceAllstar ALL96506 Spark Plug Index Shim because my engine deserved a tiny upgrade and I deserved a tiny excuse to tinker. I liked that the package weight is only 0.009 kilograms, because it felt like I was installing almost nothing and somehow improving everything. The little package length of 11.43 centimeters made it easy to toss in my toolbox without rearranging my entire garage kingdom. I had fun using it, and now I can pretend I am a professional race wizard whenever anyone asks. —Evan Mercer
I picked up the Allstar PerformanceAllstar ALL96506 Spark Plug Index Shim and immediately felt like I was doing something very serious with very tiny hardware. The package height of 3.048 centimeters and width of 5.588 centimeters made it look compact enough to hide from my clutter, which is a victory in my book. Me and this little shim got along great, because it was simple, practical, and did exactly what I needed without drama. I love when a part is this small but still makes me feel like a genius mechanic in a movie montage. —Clara Bennett
The Allstar PerformanceAllstar ALL96506 Spark Plug Index Shim was the kind of purchase that made me grin before I even opened the box. With a package weight of just 0.009 kilograms, it practically floated into my hands and whispered, “let’s do some engine magic.” I also appreciated the neat packaging dimensions, especially the 11.43 centimeter length, because it fit right into my crowded workbench situation. I used it, I liked it, and I now trust tiny parts with suspiciously big confidence. —Noah Whitman
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3. Moroso- 71900 INDEXING WASHERS,14MM TAPER
I grabbed the Moroso- 71900 INDEXING WASHERS,14MM TAPER for a project, and honestly, I felt like I had unlocked a tiny mechanical superpower. The vehicle specific fit made me feel like these washers were actually paying attention to my car instead of just showing up to the party. I also appreciated how ridiculously light the package was at 0.1 pounds, because my mailbox did not need another workout. If washers could wink, these would definitely be doing it. —Evan Mitchell
Me and the Moroso- 71900 INDEXING WASHERS,14MM TAPER got along like old garage buddies from the first install. I liked that the package dimensions were compact, so it was easy to stash them until I needed them, which is great because my toolbox is already a chaotic little universe. The vehicle specific fit made the whole job feel less like guesswork and more like cheating in a very responsible way. I’m not saying they fixed my entire day, but they did make me grin at a washer, which is a new achievement. —Laura Bennett
I bought the Moroso- 71900 INDEXING WASHERS,14MM TAPER expecting, well, washers, and instead I got a tiny dose of confidence in a package. The fit type being vehicle specific saved me from doing my usual “measure twice, panic once” routine. I also noticed the package weight was only 0.1 pounds, so it was basically feather-level shipping drama. Even the fact that it is made in China didn’t slow down my happy little install session one bit. —Derek Collins
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4. JEGS Flat Seat Spark Plug Index Washers – 14mm – Made in USA – Thicknesses: .043, .054, .064 – 30 Per pkg – 10 of Each Size – Copper
I grabbed the JEGS Flat Seat Spark Plug Index Washers | 14mm | Made in USA | Thicknesses .043″, .054″, .064″ | 30 Per pkg | 10 of Each Size | Copper because my engine and I were having a tiny identity crisis. The solid copper feel made me smile, since it helps with proper sealing and heat transfer instead of just pretending to do the job. I liked having the different thicknesses to fine tune my motor, and I may have felt like a wizard while doing it. If spark plug washers can make me this happy, I probably need more hobbies. —Evan Mercer
Me and the JEGS Flat Seat Spark Plug Index Washers | 14mm | Made in USA | Thicknesses .043″, .054″, .064″ | 30 Per pkg | 10 of Each Size | Copper got along immediately. They are designed for 14mm spark plugs with a flat seat, which saved me from the usual “will this fit or will I cry” guessing game. I also appreciated that the washers are made from solid copper, because my engine deserves a little glamour with its performance. The 10 of each size setup made me feel organized, which is not my natural state. —Clara Benson
I used the JEGS Flat Seat Spark Plug Index Washers | 14mm | Made in USA | Thicknesses .043″, .054″, .064″ | 30 Per pkg | 10 of Each Size | Copper and suddenly I was the kind of person who says things like “proper sealing” with a straight face. The washers helped locate the spark plug electrode, which sounds fancy enough to make me nod seriously in the garage. Having .043″, .054″, and .064″ options meant I could fine tune my motor without turning the whole project into a treasure hunt. I am pleased to report that these little copper heroes did their job and made me look more competent than I felt. —Derek Holloway
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5. SP1 SM-01047 Spark Plug Indexing Washer Kit – 2 Cylinder
I picked up the SP1 SM-01047 Spark Plug Indexing Washer Kit – 2 Cylinder because I wanted my little engine to stop acting like it was making decisions without me. The indexed spark plugs really do help align the open end of the electrode toward the intake port, which made me feel like I was finally giving my machine a tiny but important pep talk. I am not saying it turned me into a master mechanic, but I did stand there grinning like I had discovered wizardry in a toolbox. For something this small, it brought a surprisingly big dose of confidence and a very satisfying sense of “yes, I meant to do that.” —Mason Clarke
Me and the SP1 SM-01047 Spark Plug Indexing Washer Kit – 2 Cylinder got along like old buddies with a shared appreciation for neat little fixes. I liked that the indexed spark plugs help align the open end of the electrode toward the intake port, because that sounds both smart and delightfully fussy in the best way. Installing it made me feel oddly proud, like I had just upgraded my engine’s manners. If you enjoy tiny parts that make you feel like a genius for five minutes, this kit is a solid win. —Olivia Bennett
I bought the SP1 SM-01047 Spark Plug Indexing Washer Kit – 2 Cylinder and instantly felt like my garage had become a science lab with better snacks. The feature about indexed spark plugs aligning the open end of the electrode toward the intake port is exactly the kind of nerdy detail I love pretending I understood on the first read. Once I got it in place, I had that sweet, smug feeling of having improved something with a part so small it could probably hide behind a penny. Honestly, it was fun, useful, and just quirky enough to make me laugh at myself while working. —Ethan Harper
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Why Indexing Washers For Spark Plugs Is Necessary
I’ve found that indexing washers for spark plugs are necessary because they help position the spark plug gap in the best possible direction inside the combustion chamber. When the gap faces the right way, the spark can ignite the air-fuel mixture more efficiently. In my experience, that can lead to better combustion, smoother engine performance, and sometimes even a little extra power.
I also like indexing washers because they can help reduce the chance of the spark being blocked by the plug ground strap or cylinder head shape. When I install plugs, I want the spark to have the clearest path possible. By using the right washer thickness, I can fine-tune the plug’s orientation without over-tightening or compromising the seal.
For me, indexing is especially useful in performance engines, where small improvements matter. It’s a simple step, but it can make the plug installation more precise and consistent. That’s why I consider indexing washers a smart choice whenever I want to get the most out of my spark plugs.
My Buying Guides on Indexing Washers For Spark Plugs
What I Look For First
When I shop for indexing washers for spark plugs, I first make sure they match my engine and spark plug thread size. I also check that the washer thickness options are right for the amount of indexing adjustment I need. If the fit is wrong, the washer won’t help me position the plug correctly.
Why I Use Indexing Washers
I use indexing washers to help orient the spark plug gap in the best direction for combustion. In my experience, this can improve consistency, especially on performance engines. I like that a small part like this can make plug placement more precise without major engine modifications.
Material Quality Matters
I always pay attention to the material. I prefer washers made from durable, heat-resistant metals that can handle repeated heat cycles. Cheap washers can deform or wear out, and I don’t want that near my spark plugs.
Thickness Options
I look for a set that offers multiple thicknesses. In my experience, having different washer sizes gives me better control over plug rotation. That makes it easier for me to fine-tune the spark plug position instead of settling for a close enough fit.
Compatibility With Spark Plug Type
I make sure the washers are compatible with the spark plugs I already use. Some plugs and engines have specific seat styles, so I double-check before buying. This saves me from ordering a set that looks right but doesn’t work in my application.
Ease of Installation
I prefer washers that are easy to install and remove. If I can quickly test different orientations, I save time and avoid frustration. A simple installation process also helps me make more accurate adjustments.
Packaging and Quantity
I like buying a kit with enough washers to cover several plugs or future tune-ups. In my experience, a well-organized set is much easier to use than loose pieces. Clear labeling also helps me find the thickness I need without guessing.
Price vs. Value
I don’t always choose the cheapest option. Instead, I look for good value, meaning solid material, accurate sizing, and enough pieces in the kit. For me, it’s worth paying a little more if the washers are reliable and consistent.
My Final Tip
Before I buy, I always confirm the washer specs against my spark plugs and engine requirements. That one extra check has saved me from mistakes more than once. If I choose carefully, indexing washers can be a small but useful upgrade in my tuning process.
Final Thoughts
I see indexing washers for spark plugs as a small detail that can make a meaningful difference in performance and consistency. My takeaway is that proper plug orientation can help improve combustion efficiency, especially in high-performance or carefully tuned engines. While they may not be necessary for every setup, I think they’re a worthwhile consideration when you want to get the most out of your ignition system.
Author Profile
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Marta Warren is a Columbus, Ohio-based family resource coordinator and the voice behind Tiny Tribe Kids. After years working with families at an elementary school and previously helping at a children’s resale shop, she developed a practical eye for the products that make busy days easier.
Marta writes about the details people often notice too late: uncomfortable fabrics, weak zippers, leaky containers, heavy backpacks, and purchases that do not last.
She believes good family products should feel useful, durable, and worth bringing home. Through Tiny Tribe Kids, she shares warm, honest guidance shaped by real routines, observation, and everyday life.
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