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Spark Plug and Ignition Wire Removal and Installation

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The C5 Corvette comes with Platinum Tip "100,000 Mile" AC -Delco Plugs. It also comes with about 7mm, carbon resistor based, plug wires. To me the C5 LS1 deserves better.

Tools Required

Basic tools will do, but I also chose to go with the SNAP-ON Double Swivel 5/8 6-point Spark Plug Socket. This made the job MUCH easier. The part number is S9721 and it costs about $40.00.

  • Di-Electric Grease (Silicon Grease)


I chose to go with NGK TR55 Solid Copper Core plugs. They are only a couple of bucks each. These plugs match the heat range of the stock plugs and are cross-referenceable to the stockers. The NGK TR55VX plugs are the same plug, but are the platinum tipped version. They have a thinner copper core. The platinum actually won't last that long, and will break and/or burn off if you drive your LS1 hard. The solid copper TR55's won't last near as long, but will provide better performance. I estimate when driving hard, that replacement will need to come about 15K to 30K miles. The trade off is that the larger solid copper core will dissipate heat quicker than the Platinums, and will deliver a more reliable, more powerful spark. Platinums are strictly for longevity.

NGK TR55's and VX's are called V-Power plugs. This is because the center electrode is cut into a V shape.

Here is NGK's explanation of the V-groove:

"NGK's unique V-Power design directs the spark to the edge of the electrode where it can develop more rapidly. This allows easier and more complete combustion of the air/fuel mixture. The increased ignitability allows the engine to burn air/fuel ratios that would otherwise be too lean."

"The amount of spark which is absorbed by the center and ground electrode is referred to as the quenching effect. The V-Power plug is designed to draw spark to the edge of the electrode. Thus, the quenching effect is minimized, resulting in more effective, complete combustion."

If you run your engine hard in a very hot climate, and/or are running nitrous or forced induction. Then the TR6 is a better plug, because of its colder heat range. Consult with your tuner for best gapping etc...

Below is a photo of the NGK TR55(left) plug next to a Platinum stocker(right). Notice the much larger copper core on the NGK.


LS1 Wires

The LS1 uses 8 individual coil packs to deliver spark to each plug. I chose to go with Taylor Spiro-Pro 8mm Wires. Taylor wires come highly recommended from many hard core LS1 owners who race and modify their engine. I was able to speak to a rep at Taylor Vertex, and I was told they use approximately 80 windings per inch on the Spiro-Pros. This to me seems more than sufficient for the LS1, since the wires are ONLY about 6 inches long. If I were to upgrade I would look at Magnecor. They claim 200 windings per inch, and don't use "resistive enhancing" coatings which can break down in other wires. I had just a little concern about their fit though from looking at photos of their wires for the LS1. Fit, Finish, and Looks, are very nice with the Taylors. They actually use the Stock Delco boot, and end, to connect to the coil packs.



The NGK Plugs come pre-gapped from the factory, supposedly at .050 but when I used a knife type feeler gauge, they were more closer to .057 This was great to me, as I understand anything between .055 and .060 is good for our LS1's. The stock plugs are gapped at .060. Anyway, I checked all the NGK plug gaps, and all were the same at .057 so I stayed with that.

Also the NGK's have tips that can unscrew on the top where the plug wire attaches. Make sure these are snug with a pair of pliers. Don't get all crazy on them. Just a moderate squeeze of the pliers, and a moderate twist to ensure they are not loose. I opted to put a small drop of Loctite 290 Wicking Grade, on the end of each plug. Wicking Grade 290 is recommended for electrical contacts, and is made to seep into tight threads and assembled components.



    Taking a Spark Plug out when the engine is hot can result is valve warpage, or other internal warpage, due to cool air entering a hot combustion chamber. Plus you won't burn your hands :)

    Start on drivers side since it will be the most difficult. Remove the Plastic Fuel Rail Covers by gently prying them up. They should easily pop out. Pull the large vacuum line out of the brake booster and place it out of the way. (Wiggle it and pull, and it should pop out.) Also remove the rubber tube from the "black thing" which is attached to the exhaust manifold (see picture). The purpose is to provide as much room as possible for the hardest plug of all. The #7 plug at the rear on the drivers side. Just remember in a minute when you are cussing and scratching your knuckles there, that the F-body Guys have to deal with their LS1 being set back much farther under there. :(

  2. Remove spark plug wires

    Now begin removing the spark plug wires by first removing each of them from the coil pack first. They should slide of with a twist and pull. Once the plug wire is off the coil pack, reach down and remove the wire from the plug. The factory puts a metal heat shield around the wires. This will come off with the wire. Just twist wiggle and pull at the same time, and they should come off pretty easily. Don't worry about the metal shield. Just keep it with your old wires for safe keeping.

    Below is a pic of the old wire and shield, next to the new wire. The black thing at the top of the photo is the SNAP-ON double swivel socket. And in the bottom of the photo you will see the Stock plug on top of the NGK TR55.

    Better Picture of SNAP ON Swivel Socket Below:

  3. Remove spark plugs

    Once you get all the wires off, now it's time to remove the Plugs. Start with #7. The rear most plug on driver side. If you have the swivel socket, put it on, and you may want to use a long extension. Align the swivels as straight as possible, and loosen the plug. (see photo) Once loose you should be able to turn the swivel socket with your hand to get the plug out.

  4. Install new plugs

    Go ahead and work your way forward, and remove all plugs. Also keep them in order, and take note of their condition. Looks to see if they may be running to lean or too rich etc... (I will not get into that here as there are better resources on the net with photos for that).

    Once all plugs are out on drivers side, you have an option. You can begin installing new plugs, or start breaking down the passenger side.

    Once you are ready to install the new plugs. (make sure they are gapped where you want them). You will need to put anti-seize compound on the threads. Just a light coating should do. No need to get messy and crazy here. The purpose is so that when you go to take out your plugs next time, they will not be seized in the threads. On aluminum heads, this is very important. Also you will want to torque the Plugs to about 7 lb/ft - 11 lb/ft. Or once hand tight: Turn them about another 1/16th of a turn. Just be careful and use common sense. By the way, NEVER force a plug to thread initially with a wrench or socket driver. Since the heads are aluminum, you could VERY easily strip out the threads. Expect to pay big coin to have this repaired. With that said, it is pretty easy to thread the plugs with just a 5/8 inch spark plug socket and about a 2 or 3 inch extension and your HAND. Once you thread them ALL THE WAY IN, by hand. ONLY then put the driver on or the torque wrench to finish the job.

  5. Install new wires

    Once your new plugs are in and tightened properly. Begin placing your new wires on. I used a Q-Tip to place just a little silicon grease in both ends of the wires, where the metal contacts are. This will help keep moisture out, and stop any arching in the wire ends. The wires should snap solidly onto the coils and onto the spark plug tips. You should feel them SNAP.

    Here is the finished job:

    Drivers Side - Cylinder #3 #5 #7

    Passenger Side - All Cylinders

    Passenger Side Again - All Cylinders

  6. Testing

    Once everything is installed. Make sure all tools are clear, and look everything over and make sure you didn't forget something.

    Go ahead and start the motor, and listen for any strange sounds like popping or ticking. If you hear a popping or ticking sound that wasn't there before, then you either have not seated a plug tightly enough, or you have a wire not seated good somewhere. Start with the wires and check that they are pushed on firmly. You may then need to deduce by sound if a plug is not seated good enough. You shouldn't have any problems. After your engine warms up, eyeball everything is in place and nothing is touching anywhere. After you drive it a while, you may smell a slight silicon odor. This is just the silicon grease and the wires breaking in, and should go away very soon.

    That should do it. I would save the old wires and plugs if they are not to old. And defiantly hold on to the metal shields in case you need or want to go back to stock. I think some other aftermarket wires, would even allow you to use the metal shields on them.


    After going for a test drive, I tuned my radio to various AM stations and drove through the gears at various throttle positions, and also at wide open throttle. I was not able to hear any EMI or noise at all.

This page was last updated on 05/28/01 by Redshift


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