Spark Plug and Ignition Wire Removal and Installation for the C5 Corvette LS1

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

I chose to go with NGK TR55 Solid Copper Core plugs.
I got them from my local O-Reilly Parts store. 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 coating 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 have as much longevity, 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
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 nitros or forced induction.
Then the TR6 is a better plug, because of its colder heat range. Consult
with your tuner for best gapping etc…

The LS1 uses 8 individual coil packs to deliver spark
to each plug.
I chose to go with Taylor Spiro-Pro 8mm Wires. I got
them from
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 longs. 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.
Fit, Finish, and
Looks, are very nice with the Taylors. They actually use the Stock Delco
boot, and end, to connect to the coil
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.
Part Number is: S9721
Cost: About:
Where: Snap-On truck, or from their web-site,
forget to have on hand:
Di-Electric Grease
(Silicon Grease)
I am not going to list
every single step as most of it is obvious when doing plugs and wires. I
will list what I think is pertinent for those that haven’t done it on a
C5 LS1. I will include photos also. This installation was performed on a
2000 C5 6-Speed. All other C5’s should be similar or the
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.
You perform this
modification to your automobile at your own risk. I make no claim that
the information contained here is accurate, complete, or that it will not
damage your automobile, directly or indirectly as a result. The
information here is strictly done so as an educational resource, only from
my experiences.
Step 1:

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
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
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. šŸ™


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
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.

Picture of SNAP ON Swivel Socket Below:


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.


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
Once all plugs are out on drivers side, you have an option.
You can begin installing new plugs, or start breaking down the passenger
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
Step 5:
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

Step 6:
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
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
EMI Interference
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 wide open throttle. I was not able to
hear any EMI or noise at all.
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.

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