How did GM originally route or manage the spark plug wires? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

**IT Cowboy** · 02-25-2026, 02:51 PM

I have seen pics with a clip on the valve covers for the front plugs but I do no know if that is correct. Right now mine are sort of draped along the bottom of the inner fender and straight into the plug.

72c20customcamper · 02-25-2026, 09:56 PM

These are on my 68 327 motor . The wires run under the manifolds

Orange Crate · 02-25-2026, 10:26 PM

The assembly manual has the stock wire routing on pages 207, 293, 294, 295, 296, & 545. For L6, SB & BB.

**Steeveedee** · 02-25-2026, 10:57 PM

Be glad you have a BBC. The SBC wires went down the back of the block, along the oil pan, and up on either side of the gozoutta part of the exhaust manifold, with the two front wires on each side going between the motor mount and the block. Made for a real fun time at tune ups, since they were all saturated with engine oil from the leaking valve covers. I don't remember how the stock BBC plug wires run. Mine run over the valve cover with aftermarket looms. Someone is going to come up with a pic, eventually.

**Rust_never_sleeps** · 02-25-2026, 11:06 PM

Quote:

Originally Posted by 72c20customcamper

These are on my 68 327 motor . The wires run under the manifolds

I have the same on my 70 350, with the 4 tin heat shields

I had one supplemental support when I bought it

**Cali72K20** · 02-26-2026, 01:25 AM

I had some NAPA HEI replacements then changed to shorter custom wires that still fit the factory valve covers.

**MikeB** · 02-27-2026, 05:23 PM

On a 69 small block with rams horns exhaust manifolds, all the wires dropped down to the oil pan rail and came up behind the cylinder heads.

This is looking forward on the passenger side. Looks like LMC Truck as all the parts!

**70STOVEBOLT** · 02-28-2026, 12:36 PM

Can’t say how they were originally routed, but I used the GM wire looms with Packard wires that have 145 degree boots. Really looks nice. Here is a link to the loom kit.

https://www.gmperformancemotor.com/p...D7IuO1icHpQRGJ

**IT Cowboy** · 02-28-2026, 04:00 PM

Quote:

Originally Posted by 70STOVEBOLT

Can’t say how they were originally routed, but I used the GM wire looms with Packard wires that have 145 degree boots. Really looks nice. Here is a link to the loom kit.

https://www.gmperformancemotor.com/p...D7IuO1icHpQRGJ

This morning I ended up doing like this. I put a short loom connector on the top back bolt of the valve cover on the passenger side and it is pretty much hidden with the air cleaner. I separated the wires with black 3 and 2 "port" loom connectors and they blend in well. Everything is off the parts that get hot and it looks much better. It wont look factory until I get orange valve covers.

02-25-2026, 02:51 PM	#1
IT Cowboy Senior Member Join Date: Jan 2025 Location: Arizona in a van down by the river Posts: 617	How did GM originally route or manage the spark plug wires? I have seen pics with a clip on the valve covers for the front plugs but I do no know if that is correct. Right now mine are sort of draped along the bottom of the inner fender and straight into the plug. __________________ 1972 C10 Custom Deluxe Highlander 402 Freedom isn't safe, it requires you to take responsibility for your own life, your own safety, and your own success. It carries with it the possibility of failure and the understanding that you're working without out a safety net. If you give the state the responsibility for any of these you also give up the freedom that accompanies the responsibility.

02-25-2026, 09:56 PM	#2
72c20customcamper Registered User Join Date: Jul 2018 Location: Catskill Mountains,NY Posts: 9,479	Re: How did GM originally route or manage the spark plug wires? These are on my 68 327 motor . The wires run under the manifolds Attached Images __________________ Mark 72 c20 custom camper Husky edition, 66 SS396 Chevelle 1964 Hawk, 63 Avanti,62 lark 1969 AMX , 1968 c20 stepside ,85 K20 1977 Suburban sold 68 anniversary.

02-25-2026, 10:26 PM	#3
Orange Crate Registered User Join Date: Feb 2011 Location: Under the Truck Dreaming Posts: 888	Re: How did GM originally route or manage the spark plug wires? The assembly manual has the stock wire routing on pages 207, 293, 294, 295, 296, & 545. For L6, SB & BB. __________________ 72 K20 Custom Camper, D60, 14BFF, full roller 406 TPI w custom built ECU and yes..it has tow hooks, a 5 speed AND a front hitch!

02-25-2026, 10:57 PM	#4
Steeveedee Ram-A-Lam-A-Ding-Dong Join Date: Jan 2013 Location: Simi Valley, CA Posts: 11,899	Re: How did GM originally route or manage the spark plug wires? Be glad you have a BBC. The SBC wires went down the back of the block, along the oil pan, and up on either side of the gozoutta part of the exhaust manifold, with the two front wires on each side going between the motor mount and the block. Made for a real fun time at tune ups, since they were all saturated with engine oil from the leaking valve covers. I don't remember how the stock BBC plug wires run. Mine run over the valve cover with aftermarket looms. Someone is going to come up with a pic, eventually. __________________ ~Steven '70 Chevy 3/4T Longhorn CST 402/400/3.56 Custom Camper Simi Valley, CA

02-26-2026, 01:25 AM	#6
Cali72K20 Senior Member Join Date: Aug 2013 Location: CA \ OK Posts: 2,766	Re: How did GM originally route or manage the spark plug wires? I had some NAPA HEI replacements then changed to shorter custom wires that still fit the factory valve covers. Attached Images

02-27-2026, 05:23 PM	#7
MikeB Senior Member Join Date: Jul 2000 Location: North Texas Posts: 4,035	Re: How did GM originally route or manage the spark plug wires? On a 69 small block with rams horns exhaust manifolds, all the wires dropped down to the oil pan rail and came up behind the cylinder heads. This is looking forward on the passenger side. Looks like LMC Truck as all the parts! Attached Images __________________ Mike 1969 Custom/10 LWB -- owned for 37 years. 350/TH350, 3.08 posi, recent AAW wiring harness, 5-lug conversion, 1985 spindles and brakes. Hedman stainless headers. Old Air installation in progress. 1982 Custom Deluxe 10 SWB -- converted from 250-six to roller cam 350 w/ Vortec heads -- sold 1981 C10 Silverado LWB, 305, TH350C -- sold, but wish I still had it! 1969 C10 (not the current one) which I bought in the early 1980s. Paid $1200; sold for $1500 a few years later. Just a hint at the appreciation that was coming. Retired as a factory automation products salesman. Worked part-time over the years for an engine builder and a classic car repair shop. Member here for 26 years! This is the very first car/truck Internet forum I joined. I still used a dial-up modem back then!

02-28-2026, 12:36 PM	#8
70STOVEBOLT Senior Member Join Date: Jun 2005 Location: Winona Lake, IN Posts: 7,062	Re: How did GM originally route or manage the spark plug wires? Can’t say how they were originally routed, but I used the GM wire looms with Packard wires that have 145 degree boots. Really looks nice. Here is a link to the loom kit. https://www.gmperformancemotor.com/p...D7IuO1icHpQRGJ __________________ 70 C/10 SWB 402/TH400/3.73 "The Needy Beast" 200,000 Mile Club Disc Brake Club Owner installed options: Front Sway Bar Power Steering Power Brakes Cigar Lighter Courtesy Lights Deluxe Side Markers Wiper Delay Sliding Rear Window Power Windows Power Locks Sniper EFI 2015 Silverado 1500 LS 4.3/6L80/3.23 lowered 2" front & rear



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