C4 Tech/Performance L98 Corvette and LT1 Corvette Technical Info, Internal Engine, External Engine

Spark Plug Wire routing.....

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Old May 16, 2014 | 07:43 PM
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Default Spark Plug Wire routing.....

'90 L98 car, passenger side around EGR pipe. I am trying to put my wires back the way they should be. Car has aftermarket wires on it, and since i been doing some top engine work, i want to get the wire routing correct. I bought a few wire holders, but i am not sure how to route the wires away from the hot EGR pipe. It looks like there is a metal bracket that can hold the wires tight to the valve cover, but i cannot get all 4 in there. And i have some plastic spiral wraps around the wires, to help protect them. Are they suppose to be there, as OEM? Check out my picture,
Thanks for any tips.
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Old May 16, 2014 | 08:49 PM
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Originally Posted by MikeT 90 C4sixer
'90 L98 car, passenger side around EGR pipe. I am trying to put my wires back the way they should be. Car has aftermarket wires on it, and since i been doing some top engine work, i want to get the wire routing correct. I bought a few wire holders, but i am not sure how to route the wires away from the hot EGR pipe. It looks like there is a metal bracket that can hold the wires tight to the valve cover, but i cannot get all 4 in there. And i have some plastic spiral wraps around the wires, to help protect them. Are they suppose to be there, as OEM? Check out my picture,
Thanks for any tips.
I can help you out here since I've just installed new wires on my 90. my 90 had the original wires, so I had the factory routing as a guide. first of all, the black plastic wrap SHOULD be there, on the RH side only - cylinders 2, 4, 6, and 8. that bracket you are talking about, it's really a two step bracket - the lower part holds only one wire - #8, #'s 2, 4, and 6 are in the upper part of the bracket. the wires wrap around the back part of the valve cover, and there is a 4-wire plastic holder. from there the wires route under the wiring injector harness, up to the distributor. there is a 5-wire plastic holder to the distributor. the wires in the are, right to left, #1, 8, 4, 3, and 6. my replacement wires are taylor 8mm silicon, and seem to fit pretty close to factory. here's a shot of my original routing at the distributor. the last three pics are the new taylors.









Last edited by Joe C; May 16, 2014 at 09:03 PM.
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Old May 16, 2014 | 09:51 PM
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Originally Posted by Joe C
I can help you out here since I've just installed new wires on my 90. my 90 had the original wires, so I had the factory routing as a guide. first of all, the black plastic wrap SHOULD be there, on the RH side only - cylinders 2, 4, 6, and 8. that bracket you are talking about, it's really a two step bracket - the lower part holds only one wire - #8, #'s 2, 4, and 6 are in the upper part of the bracket. the wires wrap around the back part of the valve cover, and there is a 4-wire plastic holder. from there the wires route under the wiring injector harness, up to the distributor. there is a 5-wire plastic holder to the distributor. the wires in the are, right to left, #1, 8, 4, 3, and 6. my replacement wires are taylor 8mm silicon, and seem to fit pretty close to factory. here's a shot of my original routing at the distributor. the last three pics are the new taylors.




THANK YOU JOE C.! exactly what i wanted to know. I did see that lower bracket, and was wondering if a wire should go there. Makes sense, put the #8 wire there and 2,4,6 in the upper bracket. I had the sleeving on 3 wires, but had to dig up some extra for the 4th. I will now make it right. I have the 5 wire holder, just didnt know it was so close to the dist. And i have an extra 4-wire holder, i can put that one closer to the valve cover.
Now what i disagree with you is the wires coming off the dist. I have a 90 FSM, and it clearly states wires #2 and 3 must be routed in front of the dist. and i dont think #1 should be in the 5-wire holder. I think it should be #2. Maybe your #1 wire is too long, so you routed it that way? I have my dist back in, and the wires connected. i just need to get the holders in correct position, and get #3 in the 5-wire holder. With it closer to the dist, i think i can make it work. I dont know the brand of my aftermarket wires. But they say "wired for life" on them, and they are 8mm blue wires.
I do have some C4 books, and they show pics of L98 motors various years, and the 5 wires in the holder. The detail is not as good as your pictures. I see you have the yellow Bosch injectors....last year i put in the blue Bosch IIIs.....i like them!
Actually now that i look at your first picture of which you say is factory, i think that cannot be. The factory dist has a plastic "ring" that holds the tops of terminal boots down. all 8 wires will come up off the dist in the ring, and it is supposed to be numbered. i dont see your ring, and the wire boots do not have a lip to catch the ring. Not trying to cause trouble here....

Last edited by MikeT 90 C4sixer; May 16, 2014 at 09:57 PM. Reason: update
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Old May 16, 2014 | 10:37 PM
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Thanks Joe C. Great pics. I have all 4 wired crammed in the upper bracket. Very nice wire routing also. Do you have pics of the driver side also? I really don’t have a clue how they should be tucked away.
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Old May 16, 2014 | 10:43 PM
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Originally Posted by MikeT 90 C4sixer
THANK YOU JOE C.! exactly what i wanted to know. I did see that lower bracket, and was wondering if a wire should go there. Makes sense, put the #8 wire there and 2,4,6 in the upper bracket. I had the sleeving on 3 wires, but had to dig up some extra for the 4th. I will now make it right. I have the 5 wire holder, just didnt know it was so close to the dist. And i have an extra 4-wire holder, i can put that one closer to the valve cover.
Now what i disagree with you is the wires coming off the dist. I have a 90 FSM, and it clearly states wires #2 and 3 must be routed in front of the dist. and i dont think #1 should be in the 5-wire holder. I think it should be #2. Maybe your #1 wire is too long, so you routed it that way? I have my dist back in, and the wires connected. i just need to get the holders in correct position, and get #3 in the 5-wire holder. With it closer to the dist, i think i can make it work. I dont know the brand of my aftermarket wires. But they say "wired for life" on them, and they are 8mm blue wires.
I do have some C4 books, and they show pics of L98 motors various years, and the 5 wires in the holder. The detail is not as good as your pictures. I see you have the yellow Bosch injectors....last year i put in the blue Bosch IIIs.....i like them!
Actually now that i look at your first picture of which you say is factory, i think that cannot be. The factory dist has a plastic "ring" that holds the tops of terminal boots down. all 8 wires will come up off the dist in the ring, and it is supposed to be numbered. i dont see your ring, and the wire boots do not have a lip to catch the ring. Not trying to cause trouble here....
I agree, the FSM does say to route 2 and 3 in front of the distributor, but this my second 90, both original, and both routed to the rear. it wouldn't be the first time there was a typo in the FSM. wires 1, 2, and 3 route to the rear, and are held behind the distributor with a 3-wire clip. this routing has been verified by more than one member here.

here's a pic of a 1990 vintage NOS L98 engine - note the routing at the rear of the distributor



as far as the ring on the distributor holding the wires, I've had three L98 C4's, and none of them had any ring holding wires. the wires in my first pic are the originals (note the number 8 on the one wire by the distributor. only original factory wires were number for the cylinders, and factory wires do not have a lip on the distributor boot. there is no ring, because there's not supposed to be one. see pic -



in one of my virtual photo albums, I have pics of my first 90 with the original wires, and their routing. both my 90 were original, and both routed and configured the same way. if I can dig them up, i'll post.

I stand by all my statements!

Last edited by Joe C; May 17, 2014 at 04:25 AM.
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Old May 16, 2014 | 11:37 PM
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I have noted the routing information in the FSM indicating that 2 and 3 are in front of the distributor..... however..... I have yet to find a 90 wired that way...all are behind. Here's a case where there seems to be an error in the manual.
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Old May 16, 2014 | 11:44 PM
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Originally Posted by gmboileau
i have noted the routing information in the fsm indicating that 2 and 3 are in front of the distributor..... However..... I have yet to find a 90 wired that way...all are behind. Here's a case where there seems to be an error in the manual.
bingo!!!

Last edited by Joe C; May 17, 2014 at 12:00 AM.
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Old May 17, 2014 | 01:32 AM
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the last three pics are the new taylors.
As an aside, looks like you have a non-standard wrap on the EGR tube; may I as what it's made of??
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Old May 17, 2014 | 01:47 AM
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Originally Posted by 65Z01
As an aside, looks like you have a non-standard wrap on the EGR tube; may I as what it's made of??
http://www.designengineering.com/cat...-lr-technology

bought a roll 1" X 15' on fleabay. it's been on several months, about 1000 miles. doesn't seem to be any issues.

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Old May 17, 2014 | 02:35 AM
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Originally Posted by MikeT 90 C4sixer
Now what i disagree with you is the wires coming off the dist. I have a 90 FSM, and it clearly states wires #2 and 3 must be routed in front of the dist.
My FSM states that also, but they were not routed that way from the factory. All the wires go around behind the distributor. The picture in my FSM shows a CARBURETOR, so I have little confidence in it.

Originally Posted by MikeT 90 C4sixer
i dont think #1 should be in the 5-wire holder. I think it should be #2.
Mine is routed the same way it came from the factory and #1 is in that 5-wire holder. Here's my setup (I don't have a picture of the 5-wire holder):



Originally Posted by MikeT 90 C4sixer
Actually now that i look at your first picture of which you say is factory, i think that cannot be. The factory dist has a plastic "ring" that holds the tops of terminal boots down. all 8 wires will come up off the dist in the ring, and it is supposed to be numbered. i dont see your ring, and the wire boots do not have a lip to catch the ring.
I have always bought AC Delco spark plug wires (several sets over the years) and NONE of them came with the boots that fit that ring. I just found it and threw it away about a month ago... For reference purposes, this is what it looks like:

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Old May 17, 2014 | 10:55 AM
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Originally Posted by Joe C
I agree, the FSM does say to route 2 and 3 in front of the distributor, but this my second 90, both original, and both routed to the rear. it wouldn't be the first time there was a typo in the FSM. wires 1, 2, and 3 route to the rear, and are held behind the distributor with a 3-wire clip. this routing has been verified by more than one member here.

here's a pic of a 1990 vintage NOS L98 engine - note the routing at the rear of the distributor



as far as the ring on the distributor holding the wires, I've had three L98 C4's, and none of them had any ring holding wires. the wires in my first pic are the originals (note the number 8 on the one wire by the distributor. only original factory wires were number for the cylinders, and factory wires do not have a lip on the distributor boot. there is no ring, because there's not supposed to be one. see pic -



in one of my virtual photo albums, I have pics of my first 90 with the original wires, and their routing. both my 90 were original, and both routed and configured the same way. if I can dig them up, i'll post.

I stand by all my statements!
I just love these forums. When you question the authority, you get more answers! It wouldnt surprise me at all if the FSM was wrong. I have seen torque values for the same bolt different in different sections of the manual, so i guess it is not gospel. I will agree that the factory wires had the numbers on them, so does the "invisible" ring. I have a Haynes shop manual for C4s, and it shows the ring and how to take it apart. Hmmm, wonder what year they took it out? I just cannot see running wire #1 all the way around the dist, unless it is just too long to go anywhere else. Now there is plenty of room behind the dist, so no worries. In fact, i think i had at least 2-3 running behind the dist when i took it all apart.

But actually i just switched wires 1 and 3, cuz 1 was so long and i wanted to run it like the FSM. 3 will have to go around one way or another. I will work on it today, and take a picture of what i come up with.
Love the pic of the vintage NOS engine.....shows the wires on drivers side good. I have the one corner bracket/wire holder, but do not have the one further in. I am thinking wire 1 goes the other way, cuz the boot is just too close to the plenum? I might have re-do several wires! These coil in cap dist's are HUGE!
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Old May 17, 2014 | 10:59 AM
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Originally Posted by Cliff Harris
My FSM states that also, but they were not routed that way from the factory. All the wires go around behind the distributor. The picture in my FSM shows a CARBURETOR, so I have little confidence in it.

Mine is routed the same way it came from the factory and #1 is in that 5-wire holder. Here's my setup (I don't have a picture of the 5-wire holder)

I have always bought AC Delco spark plug wires (several sets over the years) and NONE of them came with the boots that fit that ring. I just found it and threw it away about a month ago... For reference purposes, this is what it looks like:

That is the ring i am talking about. I have had some older Chevys with it, so i know it exists. Just odd they couldnt update the manuals.....did any C4s have this wire ring?
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Old May 17, 2014 | 01:17 PM
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Originally Posted by MikeT 90 C4sixer
...i have a Haynes shop manual for C4s, and it shows the ring...
so does the 1990 FSM, but that doesn't make it right!

Originally Posted by MikeT 90 C4sixer
That is the ring i am talking about. I have had some older Chevys with it, so i know it exists. Just odd they couldnt update the manuals.....did any C4s have this wire ring?
I know that 1985 and 1990 models do not have that ring.

Last edited by Joe C; May 17, 2014 at 01:33 PM.
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Old May 17, 2014 | 07:43 PM
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Well here is what i came up with today. I think they ended up ok. I broke one of the end tabs on the 4-wire holder, but i had a brand new black holder so it was ok. Wires 1 &3 were a little tight, but should be ok. I think there is just too much going on in front of the dist, so they run the wires in the back. What do you think?
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Old May 17, 2014 | 09:10 PM
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Originally Posted by MikeT 90 C4sixer
Well here is what i came up with today. I think they ended up ok. I broke one of the end tabs on the 4-wire holder, but i had a brand new black holder so it was ok. Wires 1 &3 were a little tight, but should be ok. I think there is just too much going on in front of the dist, so they run the wires in the back. What do you think?
I think you did good!
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Old May 17, 2014 | 10:05 PM
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Originally Posted by Joe C
so does the 1990 FSM, but that doesn't make it right!

I know that 1985 and 1990 models do not have that ring.
My 1985 came with and still has that ring.
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Old May 17, 2014 | 10:43 PM
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Old May 17, 2014 | 10:54 PM
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Originally Posted by Joe C
I think you did good!
Glad you approve, and thanks so much for your help!
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Old May 18, 2014 | 06:21 AM
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Originally Posted by TBSS/85vette
My 1985 came with and still has that ring.
interesting - did you buy your 85 new? I bought my 85 with 33K miles - everything was pretty much original, original wires, distributor cap, and as I remember, there was no ring, and the wire boots were not configured to be used with any ring. [B]can you post a pic? I'd be interested in any clearance issues with the rear part of the plenum.

here's a pic of a 26K mile 85. it looks to be original, with the original sparkplug wires (note the "1" on the #1 wire near the front VC fastener). if you look closely, I doesn't appear to have any distributor cap ring. again, TBSS/85vette, can you post some pics - really curious here...





Last edited by Joe C; May 18, 2014 at 07:50 AM.
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