Okay, I will start by saying that I love my 94 Z28...great car, solid build (for the most part) and a lot of fun. All in all, a good reliable machine. Only one issue... According to my stepfather (who has been working on Chevy's and Fords longer than I have been alive) says that the LT1's are notorious for chewing up the spark plug cables. At first I'm thinking "Oh, no biggie, just by some new cables and pop 'em on!" Wrong. Seeing as how this is the first Z28 I have ever even sat in, I didn't realize that the spark plug cables for the LT1 were UNDERNEATH the engine. What I am really looking for is some helpful tips on how to change the cables and not have it take the whole day. I have access to a lift and I have the cables...do you have to roll this engine to get to each side for the cables?? I really hope not...
Perhaps I should also let you know WHY I am changing the plug cables. Just recently...since the 2nd of December, the car has started to drive really ruff, then suddlenly starts sputtering between 40 and 60 mph...now it idles harsh and kind of jerks when I am in reverse...and shortly after all of this it starts to chug really hard just driving at normal speeds (normal being the speed limit of 25 on base)! Pretty sure that it's just a faulty cable and the engine is missfiring now...well, I hope that is all it is because I just bought the thing.
Like I said, if anyone has any helpful hints on how to prolong the life of my cables, let me know.

 

Just get ready for busted,cut up knuckles...You dont have to "roll" the motor..just take your time and do 1 wire at a time,while your at it change the plugs.

 

The driver's side is easy. The passenger side is a bitch. Removing the alternator, which is not hard, allows easier access to 2 and 4. Be sure to re-install the heat shields. If they're missing, they go on 6,7, and 8, have a dealer order them. They're fairly cheap.

 

Your spark plug wires will last as long as in any other car with or without the heat shields. There's nothing different about the LT1 where wires don't last as long. You may have bad wires if they are original because they are ancient, and some aftermarket wires aren't too good, but stock wires and most aftermarket wires are good. If I were you, I'd just get OEM replacement 7mm wires. In addition to removing your alternator, you will have to loosen your power steering pump to get the passenger side wires routed through where they have to go. You should do plugs at the same time. Use some dielectric grease on both ends of the wires and make sure they snap into the distributor. But be prepared if that doesn't fix your problem, then you have to replace your front mounted distributor which are known to cause problems like you are having, especially on a 94.

 

If plug wires will last just as long without heat shields, then why did the ones I left the heat shields off bake, and the ones that aren't supposed to have them not bake?

 

If you still have the problem after replacing the plugs and wires,I would have the Ignition control moduel checked(ICM),before you go replacing the opti spark..

 

I have some extras if you want them. You're the first person I've heard of who has kept them on his car. Silicone boots don't usually burn uneless something red hot is touching them - like metal or an open flame.

 

I agree with this and also check the connector going to the opti because those were known to corrode and cause problems. Some people had luck spacing the ICM off the head with washers to let it cool a bit - so if you get a new one that is a good thing to consider.

 

I didn't leave the 3 heat shields on, and they're the ones that baked. The other wires were fine. Started getting a miss, and the old P0300. Started checking the wires, and those 3 practically crumbled in my hand at the spark plug end. They weren't touching the manifolds, as I made sure of that when I put them on. I put the heat shields back on after replacing all the wires. I guess time will tell if the shields add any protection. And they were silicone wires.

 

Wrap electrical tape around the boots around the plug side boots and down the wire till its out of the way of any extreme heat, cheap and it works

 

Thank you, everyone, for the input. Well, shortly after I started the thread, I actually got in there and replaced the cables... and yes, it was a serious pain in the butt. I put the heatshields on all but the one that was on the passenger side...couldn't get my hand back in there with enough room to manuever the shield...so that one doesn't have it on there. Either way I put the cables on and it didn't help anything. A friend of mine, who has the same year and model as me, told me that he started having the same type of problem that I am and it turned out to be two issues. His opti spark was going out as well as a bad fuel filter. I've decided that I am just going to use the diagnostic equipment at the hobby shop, with the help of the techs there, and try and find out exactly what is wrong before I just go and start throwing parts at the car and hope to God that one of them will work... Don't have the time or money to be doing all of that, and from what I understand the opti spark is pretty expensive.
Thanks again for the suggestions. If anyone else can think of something let me know.

 

Check the fuel pressure while you're at it. If they have a good scan tool, it will come in handy, might even help pinpoint the problem.

 

make sure you dont have any arcing from the plugs to the manifolds, I had little stress cracks in my plugs, and they would heat up and arc, you would see it in the dark. if this is not the case go to the scan tool, fuel pressure test, ect

 

I was planning on checking the fuel systems. I noticed the other day that some of the wires on the injectors at the top of the engine were bare, probably can't be a good thing. I was also told that checking the fuel filter may be a good idea. Either way, I just really hope it's not the opti spark that is messed up...that would be no good.

 

Honestly, if you don't mind spending some cash then there are systems that make the LT1 ignition so much simpler. Personally I run the LTCC with the coils mounted on billet fuel rail covers (though I'm working on relocating them to the frame rails). Changing wires takes all of 5 minutes once you make them.