Parts

Tools and Tech Tips for Pulling and Installing Spark Plugs

(Image/Wayne Scraba)

In some vehicles, pulling and replacing spark plugs is a nightmare: Impossible to reach plugs. Headers, shock towers, and air conditioning parts in the way. 

Factor in the multiple opportunities to melt your skin and it’s no surprise many folks avoid it like the plague. (Decades ago my wife had a brand spanking-new V8 Monza. Ask me why I only changed seven plugs.)

Of course, if you have a race or high-performance car, you’ll have to get at the spark plugs one way or another. 

Plus, you’ll need to examine and read the old plugs, gap the new plugs, and maybe index the plugs and so on.

There are a lot of tools out there to help you with these chores. We’ll show you a few examples in the following captioned photos.

I’ll also show you some ancient (no longer available) tools I’ve used for decades (Post-V8 Monza!). 

We’ll also provide some tips on installing the plugs. Check it out:

Pulling (and installing) spark plugs is much less of a chore if you use the right tools. One special vintage tool in my collection is a Champion 14-MM “Plug Mate” spark plug socket (part number CT901). The 3/8-drive socket is rubber lined and as you can see, it also has a 7/8-inch hex on the end. This obviously allows you to use a wrench on it if you can’t access the drive with a ratchet. It also has a nice knurl on it, which makes hand turning a bit easier. Finally, the socket is relatively short at 2-1/2-inches overall length. (Image/Wayne Scraba)
(Image/Summit Racing)
Summit Racing sells a very interesting stubby socket from the folks at SLP Performance. What makes it unique is that it is open ended and very short. This allows you to gain access to those “impossible to reach” plugs. By the way, it has a 13/16-inch hex. SLP part number is 30102. (Image/Summit Racing)
Here’s an old Champion Spark Plug “Plug Master II” 3/8-drive ratchet out of my tool chest. It has a bent handle and a flex head. The old part number is CT 451. Long since discontinued, I still dig this tool because the handle shape coupled with the flex head allows me to gain good access to most spark plugs. (Image/Wayne Scraba)
Wright Tool manufactures a similar job (Summit Racing part number WTC-3429). This isn’t an inexpensive ratchet, but it offers the same benefits of the old Champion job shown above. Plus, it’s readily available! (Image/Summit Racing)
(Image/Summit Racing)
Some folks have trouble peeling the spark plug boot off of a plug. If you use a small amount of dielectric grease inside the boot, it won’t seize (MSD part number 8804). Another trick is to use a boot puller such as this old discontinued example from MSD. The second photo shows how the boot puller locks in place behind the boot. To operate, simply squeeze the handles and pull. By the way, check out the Summit Racing catalog for readily available boot pullers. (Image/Summit Racing)
Another “cool old tool” out of one of my roll away cabinets is this vintage ACCEL plug gapper.  By design, the plug screws into the body, then it’s locked in place. You slide the guillotine into the gap and tighten. Each guillotine blade is a specific thickness. Once tightened, you end up with an absolutely perfect gap. FYI, these gapping tools have been discontinued for many years (and they were private label manufactured for other companies). If you find a complete setup at a swap meet, grab it. You won’t be sorry. (Image/Wayne Scraba)
(Image/Wayne Scraba)
This old Champion Spark Plugs gapping tool, part number CT-413 is also discontinued, but it too was (and still is) extremely useful. For all intents and purposes, its’ a multi-tool built with various attachments that slide out and retract back in to the main body. There’s a taper gauge on one side and a dual-sided electrode bend bar on the other. One side has a file while each end has a series of slide out wire gap gauges including .025, .028, .030, and .032-inch on one end and  .015, .020, .035, and .040-inch jobs on the other side. It’s an old favorite of mine and if you locate one used, grab it up. (Image/Wayne Scraba)
This spark plug gapping tool from Allstar is similar in principle to the old ACCEL job shown previously. In operation, you insert the plug into the holder, insert the feeler gauge, and gently turn the knurled knob until the feeler gauge is snug. Done! It’s available from Summit Racing under part number ALL96516. (Image/Summit Racing)
Here’s an inexpensive wire gap tool that works great and definitely won’t break the bank. It’s manufactured by Lisle and sold through Summit Racing under part number 67900. (Image/Summit Racing)
Indexing plugs is still common in racing, particularly in high compression ratio applications. In order to “index” spark plugs, the insulator body must be marked with a felt marker (don’t use pencil because it can create a carbon track for sparks to follow). The first step is to place a long mark on the side of the plug where the ground electrode attaches to the spark plug body. Rather than rummaging through boxes and boxes of spark plugs in an effort to locate the perfect (and sometimes unobtainable) combination of plug threads that match the head threads, use aftermarket indexing washers such as these models from Moroso. (Image/Wayne Scraba)
There are several different washer kits available, each with different thicknesses. Once the correct washer is installed on the spark plug (you might have to try several different washers to get it right, but don’t stack washers), simply tighten the plug in the cylinder head. Given the varying washer thickness and the soft nature of the copper gasket, you can “adjust” the index mark on your spark plug so that the electrode is correctly situated in the cylinder. One word of caution: In most cases, the engine will respond to a gap that faces the center of the cylinder or angled slightly toward the exhaust valve. On the other hand, some engines “like” different electrode positions. It all depends upon your engine. (Image/Wayne Scraba)
There are several different spark plug “viewers” or magnifiers available on today’s market, but one of the least expensive is a simple photographer’s “lupe.” In essence, this is a simple plastic magnifier that is available in a number of different magnification powers. The example shown is an 8x version. By the way, these are available at any camera shop and are extremely inexpensive.  Another inexpensive option is simply a lighted magnifier. They have sufficient magnification you can actually examine the spark plug closely. (Image/Wayne Scraba)
A top line spark plug viewer Summit Racing sells is this job from Nitrous Outlet. This plug viewer will give you the ability to dig deep into the spark plug for details such as air-fuel ratio, timing, plug temperature, and perhaps most important, detonation. Bottom line here is, this is a high-quality tool. (Image/Wayne Scraba)
Here’s another old tip that still works: To install plugs into a really tight area, slip the porcelain of the spark plug into the end of a rubber hose. Then you can manipulate the hose to get the threads started. This is definitely an old tip that still works. (Image/Wayne Scraba)
I’ve always used a little dab of anti-seize on spark plug threads. It’s particularly important with aluminum heads. Some folks scoff at it, but here’s the straight scoop from Champion Aerospace: “Apply anti-seize sparingly to the second and third threads. Do not contact the electrode(s) as it could short out the plug.” Basically, if it works on airplanes, it will work on cars. (Image/Wayne Scraba)
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6 Comments

  1. Pingback: Tools and Tech Tips for Pulling and Installing Spark Plugs

  2. G.M.s were the worst about spark plug placement. I’m convinced their engineer’s designers decided to put them in the most difficult spots to drive the mechanics insane. Ford with the 18mm plugs another great idea…. I’ve broken a few of those wound up sending heads to a Machine Shop and the infamous “Peanut Plugs” another joke. And of course now with 50+ brands & designs it just plain crazy, KICKING A HORNETS NEST?.I prefer to use the spark plug from the guy who invented it…. Robert Bosch. That’s Me!

  3. Pingback: Stuff from D. August 9th, 2020 – Darryl's Drive In

  4. Spark plugs are enjoyable to change on a Sunday afternoon after having had sex that morning.

  5. Hi Wayne,
    Loved this article. I was having some difficulties to install spark plugs on my car. This article solved all those difficulties.
    Thanks for the article!

  6. Louis (socketman) says:

    Wayne, you can buy a bent handle flex head or a straight handle flex head ratchet lots of places.The anti seize is not always recommended. Some spark plugs are now coated from the factory NGK does this.

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