Replaced my spark plug wires - phew! (Tips included)

Phew! (Wiping sweat off forehead) I got all my spark plug wires replaced! I feel like it was an accomplishment because this is the first time I have tackled the task, despite 20 years of LT1 B-body ownership. I now understand why it has such an dreaded reputation.

I replaced the spark plugs last year (at just over 100k), but did not do the wires because it looked so daunting. I went ahead and tackled it now because my water pump died, the removal of which makes the distributor much easier to get to. I am still not clear how the wires could be replaced without removing at least both belts and the mechanical fan. Is that even possible?

The actual job of replacing wires was both easier and harder than I expected. Utilizing upper, lower and sideways (through fender well opening) approaches and pretending my arms are rubber and super flexible, I got it done. The passenger side was harder, of course, but the driver side wasn't easy. The ABS brake lines make what should be simple access hard , with gaps just barely big enough to get a hand through. Undoing the plastic clips is kind of tricky. I am amazed that after 23 years they are not more brittle. I didn't break any.

I watched a couple Youtube videos (most LT1 videos are F-body, but that's usually not a problem) and I ended up doing it differently than them. No one recommended removing the long wire bracket on the driver side that contains the #7 wire, but I decided that was the best way to do it. It looks like that is actually designed to be removed because the rear bolt just has to be slightly loosened (approach from under car) and the bracket slides out. The front bolt goes through a hole and has to be fully removed but it is easier to access (approach from the top). After placing the new #7 wire in the bracket and running it from the front and in behind the exhaust manifold pipe (approach from top), it slid back on its rear bolt pretty easy. Then just put the front bolt back in and tighten down the rear bolt.

The passenger side didn't require removing the bracket. The tricky part is threading the wires out of and back into the gap behind the AC compressor. The clip right there that holds all 4 wires is really hard to access. I removed the bracket that holds the clip (one bolt on front of block), which seemed like the only way to do it without breaking the plastic clip. To put the new wires in, one video used a stiff electric wire to hold the spark wires to push them through the gap. I didn't need to do that. I just carefully threaded them one at a time into the gap from the front a little way, then I could reach it through the fenderwell opening and pull it the rest of the way to the spark plug.

I would highly recommend labeling the distributor end of the wires, so you can see which wire is which when they are in place and ready to be plugged into the opti (my original wires had the numbers marked from the factory on the wires, but new ACDelco ones don't have that). I used a silver sharpie, but I would have done better with a paint pen if I had one. The sharpie wears off if you handle the wire ends very much. Write the # multiple times so at least one will remain legible.

I made the unpleasant discovery that my #8 spark plug was not tight. Good thing I was back in there doing this job since apparently I did a poor job torquing it in last year.

This is newest car I have ever replaced spark wires on. I can't imagine doing it on something with a transverse V6! This was hard enough even on my relatively old school Roadmaster. It is a doable job, it just takes time, patience and deliberation.

on most, especially, newer 6's you might be able to get at the rear plugs from underneath, but most of the time it is factory recommended to disconnect the front engine mount to allow the entire engine to be rotated forward to give more clearance on the backside.

I've helped my siblings do plugs on almost every vehicle they've had, which surprising enough where all newer then anything I've ever owned.

great info jon7190!

I am going to have to do them on the wife's car. Who ever did them last didn't place the wires into holders/clips so the wires are kind of flopping around. Are they clam shell style or just C shaped?

Clam shell I believe. Hinged on one end. Give them a good pull and they will slide off their prong, then they are easier to get a screw driver in the right place to open them.

The loose wires, that is why I like to do things like that myself. I dont trust a random shop to do a good job. Of course, I haven't finished putting the cooling system back together, so I don't know yet if the car will work right! Fingers crossed.

wow - that story makes me glad i paid my mechanic to do that a few years ago.

Serendipity96 wrote:

wow - that story makes me glad i paid my mechanic to do that a few years ago.

Very understandable reaction! I am glad I did it myself, though. It was satisfying in the end and going through the process, I could see a lot of places where corners could be cut, such breaking clips or running wires where they could be too close to the exhaust and have problems down the road. I wouldn't mind giving the job to a mechanic, but I would have to be able to trust him to be thorough and would probably have to pay him a lot to do it right.

Just an update: with the amount of work and family obligations I have, it took me about two months to finish this job. That's two months (!) that the car was on jacks in my garage. Fortunately, I don't rely on it for daily transportation, but there were a number of times when I missed having it available. But that's my crazy life, it took two months to get the 5 or 6 solid work sessions it took to disassemble the water pump and opti and replace the spark plug wires, cap and rotor on the opti and put it all back together again.

I was praying hard that it would work because who knows how long it would take me to trouble shoot and redo things. Fortunately, it started right up, runs very well and there are no coolant leaks. We'll see if replacing the opti and water pump shaft seals makes any difference in the amount of oil leaking. Next I plan to replace the oil level sensor next time I change the oil because that is definitely leaking.

Thanks to everyone who gave advice in this process, as well as past advice to others that I found on archive searches!

i wouldn't mind doing an engine rebuild if the engine was taken out of the car and put on a stand.

I also couldn't take my time to do the tune-up - was my only car at the time. Like the other 2 times I had to replace a starter (napa brand is crap btw)
the last one i put in with the car only pulled up onto the curb - took me only about 30 min that time I think.

jon7190,

I just finished changing my plugs and wires using the info you provided in your post.

It made it a lot easier, thanks for posting.

It was terrible still, but I had my son's help to hold lights, and aid in fishing wires through the tougher spots.

It still took us 4 hours though, and we filled the swear jar in the garage with enough money to buy a new Optispark, but I think I used good parts and it shouldn't need to be done again for a long, long time.

My car has just a little over 90,000 miles and the plug wires were original, so hopefully I can go another 90,000 miles on these new wires and the Iridium laser plugs I just put in.

Thanks again for sharing your experience.

Still on the same plugs and wires and Optispark, I have 245,000 miles, but I only put on the last 100,000 miles. Runs great, no missing. I have had to change the waterpump and reseal intake manifold and front cover, and rebuilt the 4L60e trans in my house. Just this month, new radiator I put in.

I did advance the optispark a few degrees by grinding oblong holes for the 3 attaching bolts. It made a noticeable improvement in engine power. It was about 3/16 inch  of metal removed. No ping on regular gas afterwards. Rotate optispark against the direction of rotation.

And you could put it back to stock by moving it back. My guess, they set this up retarded from optimal to lower peak combustion temps which lowers NOx .