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I'm in the process of replacing plug wires on the '77. The new wires do not match up exactly with the wires that are on there now, lengthwise. The new wire set has two wires that are longer than all the others. Does anyone know where these two longer wires are supposed to go? Seems there are two possibilities:
-Plug wires 2 and 3, one from each side, which have to be routed around the distributor to the opposite side, or
-Plug wires 2 and 4 on the RH side which maybe have to be longer to get around the starter?
Keep in mind I'm using the original routing and all the original wire shielding also.
Any help I can get will be much appreciated.
Edit: Just realized the original wires were still on there. Packard, date coded 4Q/76.
Keep the originals boxed, cool find!
Attached is a cheat sheet I put together for future builds.
The first few sets I bought were full sets designed for the 77 350. They were junk and didn't fit like they should. I too install them like the factory did. I have been building my own now for over 25 years using Taylor 8mm Spiro-Pro wire and ends.
The wire is a 30' in length roll, only problem it only comes in Grey as the factory wire came. The pricing on my last Jegs order was from a couple years ago.
Hey measure your originals and see how close they come to my GM Part Number lengths.
Last edited by bmotojoe; Dec 13, 2019 at 07:11 PM.
Joe,
Thank you! That info is invaluable, exactly what I was looking for. Your OEM wire lengths and positions make total sense of how it should be based on what I'm seeing. Curiously that doesn't seem to be the way the wires are set up on my car and I don't believe they've ever been off it. In addition, the order of the wires as positioned in the rubber grommets, at least the one that I checked so far, don't agree with the '77 AIM. Exactly the reverse of what's shown in the AIM in fact. I don't have the 2,4,6,&8 position wires off yet but as soon as I do I'll measure them all and post it.
Did you notice that the lower rubber grommets have numbers offsetting the holes?
Yeah, I guess I do. That's not the way they were in there though. Left to right they were 7,5,1,3. The AIM shows L to R 1,3,5,7.
Is there a common practice of not running certain wires next to one another?
Yeah, I guess I do. That's not the way they were in there though. Left to right they were 7,5,1,3. The AIM shows L to R 1,3,5,7.
Is there a common practice of not running certain wires next to one another?
Firing order is 1,8,4,3,6,5,7,2
Picture order in grommet on my screen is 7,3,1,5
Firing order 5 is next to 7. These are the only 2 side by side cylinders that fire side by side. That's why, in your picture, 5 and 7 separated.
Firing order is 1,8,4,3,6,5,7,2
Picture order in grommet on my screen is 7,3,1,5
Firing order 5 is next to 7. These are the only 2 side by side cylinders that fire side by side. That's why, in your picture, 5 and 7 separated.
I will route the new wires in the order shown on the grommet. Strange that they weren't routed correctly though. I've owned the car since '93 and never touched the wires. At one point a notable corvette shop fixed a manifold leak, I suppose the wires could possibly have been moved then. Or the assembler on the line in '77 did it on a Monday after a weekend bender. As far as the AIM, I suppose someone could have just taken some artistic license with the picture. Photo courtesy of Willcox.
I also did the color thing like Mr.Willcox did in the AIM UPC 6Y Sheets 4&5 but followed the grommet numbering. Do you still have the 4 wire snap retainers shown on sheet 5 number 2 part number 367111? If not, the new part number for that retainer is GM 1615135. Should actually be one on each side unless you have the really, really late build 77 when they started using the 78 plastic top shielding.
Retainer Link. NOS & Replacements: https://www.ebay.com/sch/i.html?_fro...15135&_sacat=0
Do you hope to notice a difference replacing those 43+ year old wires?
I also did the color thing like Mr.Willcox did in the AIM UPC 6Y Sheets 4&5 but followed the grommet numbering. Do you still have the 4 wire snap retainers shown on sheet 5 number 2 part number 367111? If not, the new part number for that retainer is GM 1615135. Should actually be one on each side unless you have the really, really late build 77 when they started using the 78 plastic top shielding.
Retainer Link. NOS & Replacements: https://www.ebay.com/sch/i.html?_fro...15135&_sacat=0
Do you hope to notice a difference replacing those 43+ year old wires?
These are the only other supports/grommets I have (other than the small clips under the 'boomerang' shields):
Looking at the AIM a little closer there are other supports/grommets shown near the plugs themselves that it appears I'm missing, assuming everything in the AIM applies which is a big assumption.
These 'block clips', upper LH corner? Can't figure out where they go from the photo.
I would expect performance would improve a bit with new wires. Check out the condition of the #3 wire:
Are you talking about the item labeled Block Clip on the diagram above? There are actually 2 parts to that retainer. The retainer and the support
The middle 4 hole grommet on the left side above is actually the plastic 4 hole plastic snap retainer, unless as I stated before you have the plastic top shielding, Left side. Right side used always.
FYI that drawing above is from a earlier non HEI ignition setup.
#6 This is the supports GM 354332, 2 silver items: https://www.ebay.com/itm/CORVETTE-IG...YAAOSw0HVWAEW8
#7 This is the retainer, just clip the ends to make it a 2 hole GM 357125: https://www.ebay.com/itm/Corvette-NO...sAAOSwn3VazN71
Last edited by bmotojoe; Dec 14, 2019 at 10:38 AM.
Having a bit of a hard time following you but since I have the chrome metal top shielding, I think I must be missing the #5 plastic snap retainer both sides and a #6 & #7 block clip retainer and support on each side. A picture of all these installed would be great if you have one.
It looks like the #5 retainer is attached to a loop shaped cable guide of some kind in the drawing. I don't have that.
I see you have a manual transmission, you wont have that bracket. It is for the TH350 Kick Down Detente Cable, it also served duel porpoises for later years. I don't know why it shows the 4 hole snap retainer on that bracket in the 77 AIM, it just doesn't align with the vertical shielding at all.
If you have the assembly manual, turn to page UPC 6Y Sheet 3, it will show the mounting of the front 2 wire support and then the retainer snaps onto that (Not Shown). The AIM doesn't show shielding on the front left, but it does on the front right.
Now on the vertical 4 hole plastic snap retainers mine are in-between the upper and lower rubber grommets.
I will route the new wires in the order shown on the grommet. Strange that they weren't routed correctly though.
Looking at AIM pics of both pre HEI and HEI there's a wire routing change. Pre HEI routing has 5 & 7 separated, HEI they're not. I'll let ignition experts answer if its because HEI systems are better shielded or if its because of right angle cap boots if because the center coil prevents routing across the caps center.
My car has a pre HEI ignition but with upgraded right angle cap boots. I routed them similar to the HEI schematic.
Well, I've been struggling with routing the four front wires, 1, 3, 2, & 4. They're factory routed between the engine mount and the block (that's bad enough) and retained in a 2-wire clips (which I did not think I had, but I do). The big problem is that the 2-wire clips don't appear to be positioned anything like the various diagrams and photos I've seen. I thought they were supposed to be bolted to the block somewhat above the engine mounts. They're not, they're down between the engine mount and the block making it impossible to get wires into or out of them.
It looks to me like they're actually mounted upside down. Photo is with the new wires routed along side the clip.
I can't believe anyone would be loosening and moving engine mounts to get wires into or out of those clips, right?
Well, I've been struggling with routing the four front wires, 1, 3, 2, & 4. They're factory routed between the engine mount and the block (that's bad enough) and retained in a 2-wire clips (which I did not think I had, but I do). The big problem is that the 2-wire clips don't appear to be positioned anything like the various diagrams and photos I've seen. I thought they were supposed to be bolted to the block somewhat above the engine mounts. They're not, they're down between the engine mount and the block making it impossible to get wires into or out of them.
It looks to me like they're actually mounted upside down. Photo is with the new wires routed along side the clip.
I can't believe anyone would be loosening and moving engine mounts to get wires into or out of those clips, right?
That is really a good photo, that's a tough shot to get. I will try and get a good shot of mine tomorrow.
And yes, if you have the HEI end boot on the wire your going to have to remove it to get it through there.
Last edited by bmotojoe; Dec 15, 2019 at 10:46 PM.
That is really a good photo, that's a tough shot to get. I will try and get a good shot of mine tomorrow.
And yes, if you have the HEI end boot on the wire your going to have to remove it to get it through there.
You still can't reach or even see the clip. You can't from underneath at all, and the only way to see it from above is with a mirror or sticking a digital camera down there. Without the boot, just the metal connector on the end still won't pull through the clip. Seems pretty much impossible.
Not that I doubted you findings I just had to try for myself, and there is NO WAY even removing the HEI end boot the crimped wire end will not fit through that retainer, NO WAY! The 357125 retainer is designed for the 8mm wire and the wire alone will pass and pull through the Loop with just the slightest resistance. I will try and see if my retainer supports are pointed up or down like yours. Even then the HEI crimped wire end is not going to pass. I build my own wire sets and cut the wires long and pull just the un-crimped wire through those retainers, even then it is a touchy feely process for the L&R fronts.
Last edited by bmotojoe; Dec 16, 2019 at 08:43 AM.
Plug Wire Length & Routing
