Service Procedures
Buyer's Guide

308 GT4/GTB/GTS Spark Plug wire replacement
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by Dom Vitarella

I installed new spark plug wires today in my GT4, so I thought I would post a few photos, and a description of the install. I am a Novice when it comes to mechanical stuff, so this is geared towards other's novices like myself who may hesitate to try something like this. I can confirm that this is an easy job. If I can do it, so can you.

I had done some searching, and it seemed that there were a few people with 308's that were happy with the Accel brand of spark plug wires, which could be obtained cheaply ($~30) from your local pep boys, kragen, etc.

The set I used is the Accel Part #4040R. These are 8 mm wires, and work fine on the 308 cars. They use the radio supression core. They have the straight end boot, which fits right onto the plug extender on the 308 cars.

The photo above shows the box of spark plug wires.

The first step in the procedure is removing the distributor caps. This is the hardest part, IMO, mainly because of access. Each cap is secured by three 8 millimeter bolts, and access to them is a PITA. I think the job could be made easier if you jack up the car, and remove the wheel and wheel well so that you can access from below. I did manage to do it without doing this, but it took a little time.

Once you have the distributor cap off, on the inside, you will see the 4 set screws for the wires. (picture above). In the middle is a button thingy, attached to a spring, that you remove to access the fifth set screw which attaches the wire from the distributor cap to the coil.

To remove a wire, you unscew the set screw (be very careful, these are small, and they are made of brass, so if you drop it, it's not going to be easy finding it), and remove the wire.

Label each of the old wires prior to removing them, just in case.

Once you remove one of the old wires, the next step is to cut the new one to length. I used the old wire as a guide to cutting the new wire, but I added a little length, under the assumption that I would rather go back and re-cut the wire than accidentally cut it too short. Anyway, I think the rule goes: measure twice, cut once.

The accel kit comes with 8 wires, and each pair of wires is a different length. The shortest set of wires will reach the furthest spark plug well and then some. I used the shortest wires first, since, as you will see later, you will need to cut one extra wire for the second coil to distributor wire.

Once the wire is cut to length, you simply insert the wire into the distributor cap, and insert the set screw. The set screw will pierce the wire, and presumably create the electrical connection needed.

If you read the old archives, some posts claim that 8mm wires will fit right into the distributor cap, and some claim that the wire insulation will need to be trimmed slightly to get it to fit. In my case, I did have to trim the wire insulation slightly to get it to fit into the distributor cap. I just used a utility knife to trim it down so it would fit. Some people suggest using a little soap to lubricate the wire so it slides in easier. Do not use grease or oil as it may attack the plug wire or become an electrical issue later.

Now, remove the extender from the old wire and attach it to the new wire.

Here you can see the first wire in place. Notice that the new wires have straight ends, while the old ones have 90 degree ends. The stock 308 wire set is straight, so if you want the car to look "correct" then you want a straight set, but in terms of operation of the car, it makes no difference. Once you've done the first wire, the rest of the wires are done just the same.

Once you've done the first four wires on the front bank, the next step is the wire from the coil to the distributor cap. The accel kit comes with one of these wires, but you need two, since we have dual distributors. No problemo. As I mentioned earlier, you can use some of the excess wire that you cut off to do this. The kit comes with a bunch of extra terminal connectors, so all you need to do is crimp one on to one of the spare wires. There are even instructions in the kit to do this. Basically, you strip 1/2" of insulation away from the spark plug wire conductor core. Fold the conductor core back along the wire, and put the terminal connector over the wire and crimp into place. You put a rubber boot over the wire, and connect it to the coil. The other end connects to the distributor cap, just like the other set of 4 wires.

I tried to take photos of this step, but they all came out blurry, so you can't see much detail. Don't worry, the accel kit comes with the instructions, and a diagram. Even I was able to do it.


Tada, you've now finished the first bank. Below is a photo of the front bank after installing the new wires.

Tada, you've now finished the first bank. Below is a photo of the front bank after installing the new wires. The procedure is the same for the rear bank, but as usual, access is a PITA. Just make sure that there are no kids around to hear you swear.

Put everything into place, and start her up. Everything worked fine for me, and I hope it will for you too.