Tom454

Trying to correct previous owners handiwork and route my plug wires the correct way, I looked up the info in the (FSM) Factory Service Manual.... page 6D4-4 and I found major discrepancies between the manual and what the engine actually has on it. The metal brackets that hold the plastic wire brackets are completely different on my 87 than what the manual shows. With the brackets I have, there is no way I can use them and route the wires as depicted in the FSM. The brackets I have appear to be an OEM design, bolted to the head... i.e.- not aftermarket.

Also.... and this is odd... the FSM picture shows perimeter bolt valve covers & spark plug wire holders to match. So obviously, the FSM is wrong.

Was there a production run change for 1987?
(The engine is stamped correct, original)

Joe C

you can't go by the manual. if i'm not mistaken, seems that the tech writers used old L83 drawings in the FSM's. I would say all L98 aluminum head/center bolt VC's route wires pretty much the same way. the metal clips bolt to the head. on my 90, I tried to get it as close to factory as I could. here's several pic of my routing -

WVZR-1

This thread is maybe the only one I recall where the hardware is shown attached at the rear of the cylinder heads. The bracket on the RH rear of head I always thought was correct but most that advertise don't ever seem to include that. That's the one/maybe only discrepancy I recall.

Do you have that bracket for the rear of the RH head?

https://www.corvetteforum.com/forums...-l98-pics.html

there's left side view in this thread.

https://www.corvetteforum.com/forums...-for-sale.html

Notice the "split conduit" on the wires. That would be a nice touch in detailing one I'd think.

If you search "Corvette Challenge Engine" you might stumble upon some maybe better snapshots that either "confirm" or contradict the routing.

Tom454

Here is the bracket on the passenger side rear of the head. The bracket on the right rear of the head does not have a stub to mount a plastic wire holder.


Notice it has a spot for 2 separate plastic wire holders.

WVZR-1

^^^^

I kinda thought that was for the "side" of the RH @ the rear and NOT "rear of rear". 2 wire retainer down to 6 & 8 then 2 wire forward to 2 & 4.

Tom454

That's correct.

Here is a summary of what I have:

All 4 side metal brackets have both a vertical tab & a horizontal tab for a plastic plug wire holder. The plastic wire holders used are either for 2 wires or for 4 wires.

The metal bracket on the drivers side rear of the head has 1 horizontal tab for a plastic plug wire holder.

The metal bracket on the passenger side rear of the head does not have any tabs for plastic plug wire holders.

I'm making this guess:

Passenger side front:
vertical 2 wire holder, #2,4 plug wires
horizontal 2 wire holder, #2,4 plug wires

Passenger side rear:
vertical 2 wire holder, #6,8 plug wires
horizontal 2 wire holder, #2,4 plug wires
#2, 4, 6, 8 plug wires held away from the EGR tube (hot) by the
passenger side rear metal bracket. 3 wires above tucked behind, 1 wire below stuffed in slot. (based on pics other threads)

Passenger side rear of head, #2,4,6,8 plug wires stuffed between bracket & head, no plastic wire holders.

Drivers side front:
vertical 2 wire holder, #1,3 plug wires
horizontal 2 wire holder, #1,3 plug wires

Drivers side rear:
vertical 2 wire holder, #5,7 plug wires
horizontal 4 wire holder, #1,3,5,7 plug wires

Drivers side rear of head:
horizontal 4 wire holder, #1,3,5,7 plug wires

Altogether, this would call for (7) plastic 2 wire holders and (2) plastic 4 wire holders

?

WVZR-1

Both lefts like this:


http://www.ebay.ca/itm/1986-1991c4-c...item2341edeb14

GM# 12043158 X 7 for the 2 wire retainers.

The bracket for the rear of the right head only acts as a "guide" for the right side wires (to the VC contour) that in the link are inserted into "split conduit" they don't actually retain wires and there's no tabs for them.

In the link I see a total of 4 - 4 wire and that seems likely correct looking at an image of a wire set. GM# 12043550 for the 4 wire.

I think I can maybe do an image representative of what I mentioned.

HAD2HAV2

Hey Joe, How much longer do you have to run smog stuff on your C4 in FLA? I have to wait 35 years on my 88 in NC.

Cliff Harris

If you use the split loom in the heat shield area for the spark plug wires you must use high temperature split loom or they will melt.

Joe C

don't know how much longer, but I can't see any reason to remove it. i'm no longer a NCRS, numbers matching purest, but I still like to keep things somewhat original. as long as everything is working OK, the smog stuff stays.