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Topic: want to change plug wires

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want to change plug wires (1/5)
 4/13/21 1:28pm
James1978VetteGold Member
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1968 Convertible / 1974 T Top / 1978 custom convertible

Joined: 10/9/2020
Posts: 10

I have a 1978 with the standard 350 engine.  It runs OK, but I dont think the plug wires have ever been replaced.  So I looked under the hood and could not figure out where the plug wires are routed.   Can anyone suggest any reading material ( or video) that would tell me how to properly get to the plug wires so as to properly re-route them correctly?  I've heard that the wires for the frontmost cylinders route through the motor mounts.

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Re: want to change plug wires (2/5)
 4/13/21 2:30pm
NorskyLifetime Member
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Twin Lakes, CO - USA

SOLD - "The Toy" - 1970 Convertible
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Hi James,

I can't speak to the '78 specifically but on my '70 the plug wires were routed down from the distributor through the shielding and came up from below to the plugs.  I don't recall having to thread them through the motor mount though.  Hopefully someone with a '78 will chime in with an exact answer for you.


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Re: want to change plug wires (3/5)
 4/13/21 2:56pm
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Grapevine, TX - USA

1972 LT-1 convertible with factory air.

Joined: 8/26/2006
Posts: 1133

Looks like above the motor mount.



Wish it were easier to upload a pic from the interwebs.



Re: want to change plug wires (4/5)
 4/13/21 9:38pm
Adams' AppleLifetime Member
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Duncanville, TX - USA

#1-1974 L-48 4spd Cp Med Red Metallic/Black deluxe int w/AC/tilt/tele./p/w-p/b/ Am-Fm/map light National/Regional/Chapter NCRS "Top Flight" #2-1985 Bright Red/Carmine Cp.L-98/auto Member: NCRS, NCRS Texas, Corvette Legends of Texas

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The #1-3 & 2-4 wires are originally run behind the engine mount. If you study the pic Gary linked to you can see they go behind the mount. It's a pita, but that's how they are run from the factory, and it's the best way to run them to keep them from being melted from the exhaust.

|UPDATED|4/13/2021 6:38:57 PM (AZT)|/UPDATED|

Joel Adams
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Re: want to change plug wires (5/5)
 4/20/21 9:18pm
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Murphy, TX - USA

1974 Silver Coupe 2019 Silver Grand Sport Coupe

Joined: 5/13/2020
Posts: 2

If you buy the prefabricated wire sets, like from Summit, the wires for 1, 3, 2, and 4 are too short to route per the original factory routing through the engine mounts; and besides, not sure you can get them through there with the boots on.  I found it quite easy using bulk wire and doing my own terminations.  Thread the wire behind the mount up from the bottom, crimp on a terminal, install the boot, and attach to the spark plug.  Then route the other end to the distributor, cut to length, and terminate.  With some homemade looms, my wires are safely distanced from the exhaust manifolds.  Full disclosure: my ‘74 L82 does not have any of the OEM shielding remaining.  

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