Wiring Harness question - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Jimbotronics · 08-13-2005, 09:15 PM

Is there any difference between a big block wiring harness and a 350 wiring harness? I'm speaking of both the underdash and the engine bay harnesses.

**clay68c10** · 08-13-2005, 09:29 PM

Under dash should be the same, it only changes with gauges or idiot lights and not engine type. Under hood stuff may be different for BB/SB...

Jimbotronics · 08-13-2005, 09:32 PM

Cool - I'm changing from idiot lights to gauges so that's works out. I'm hoping the engine harness is the same as well.

**clay68c10** · 08-13-2005, 09:44 PM

I bet you can make the eng harness work even if it is different, my old SB truck was originally a 292 and everything worked ok.
Even if your harness is beat up, the replacement and upgrade (HEI and internal regulator alt) harness are pretty cheap. I got both underhood harnesses from GMCPauls for around $250. That's cheap insurance to not have a short and possible fire.

70GMCer · 08-14-2005, 07:22 AM

I bought my engine harness from MotherTruckers and got the HEI upgrade with it. He's the least expensive I found, and the harness fit like a glove and looks great. I don't think there is any difference between SBC & BBC engine or dash harnesses. There is a difference between an auto or manual trans engine harness though. Mine was a manual and when I ordered the harness, was asked if it was a manual or auto trans.

mplex2000 · 08-14-2005, 08:48 AM

Does anybody know where to get the terminals themselves? (The ones inside the firewall plugs?) About 13 years ago I built a 66 Dart, and it used the same terminals. I searched everywhere and finally found them at a local parts shop. That shop went of out business several years ago :/

I've drawn up a new pinout for completely new underhood harnesses. Buying them is so damn expensive, you're only getting about $20 worth of parts for $200+ ... I just can't do it :P

My new harness integrates a pair of relays for the headlights, a rad fan relay, hei, internal regulated alt, and a remote starter solenoid. I'm ready to get it made but..I need those damn terminals!

70GMCer · 08-14-2005, 01:23 PM

Try this site for the terminals. I just found this site...

http://americanautowire.com/index.cfm

jhow66 · 08-14-2005, 09:44 PM

Napa has them.

mplex2000 · 08-15-2005, 12:04 AM

Thanks for the link, they have them!!!! Sweeeet!!! I'm so glad...now I can rewire the entire truck with all the add-on goodies for $100 (actually might be less than that!!).

You guys rock!
-Chris

70c10 · 08-15-2005, 07:47 AM

Steve, thanks for that link!

08-13-2005, 09:15 PM	#1
Jimbotronics YA YA Join Date: Aug 2004 Location: Rockledge, Fl Posts: 1,273	Wiring Harness question Is there any difference between a big block wiring harness and a 350 wiring harness? I'm speaking of both the underdash and the engine bay harnesses. __________________ Jimbo '72 SWB - 350 (frame-off resto in progress - donations accepted) '04 Chevy Avalanche '03 Cadillac CTS (wife's ride) Restoration progress - http://67-72chevytrucks.com/vboard/s...d.php?t=335707

08-13-2005, 09:29 PM	#2
clay68c10 Senior Member Join Date: Aug 2004 Location: Centennial, CO Posts: 2,933	Under dash should be the same, it only changes with gauges or idiot lights and not engine type. Under hood stuff may be different for BB/SB... __________________ ClusterTruck: 68 C10 Bought in 89, wrecked in 03. Slow low $ rebuild started '17. 6.0 & TKO http://67-72chevytrucks.com/vboard/s...d.php?t=788602 93 K1500 Short Step, 350, NV4500, EBL flash ECU. Vortec heads & roller cam someday... 05 Jeep Wrangler Unlimited. 3” lift & 6-speed 02 E320 the insurance total “free car” 13 Tahoe LTZ

08-13-2005, 09:32 PM	#3
Jimbotronics YA YA Join Date: Aug 2004 Location: Rockledge, Fl Posts: 1,273	Cool - I'm changing from idiot lights to gauges so that's works out. I'm hoping the engine harness is the same as well. __________________ Jimbo '72 SWB - 350 (frame-off resto in progress - donations accepted) '04 Chevy Avalanche '03 Cadillac CTS (wife's ride) Restoration progress - http://67-72chevytrucks.com/vboard/s...d.php?t=335707

08-13-2005, 09:44 PM	#4
clay68c10 Senior Member Join Date: Aug 2004 Location: Centennial, CO Posts: 2,933	I bet you can make the eng harness work even if it is different, my old SB truck was originally a 292 and everything worked ok. Even if your harness is beat up, the replacement and upgrade (HEI and internal regulator alt) harness are pretty cheap. I got both underhood harnesses from GMCPauls for around $250. That's cheap insurance to not have a short and possible fire. __________________ ClusterTruck: 68 C10 Bought in 89, wrecked in 03. Slow low $ rebuild started '17. 6.0 & TKO http://67-72chevytrucks.com/vboard/s...d.php?t=788602 93 K1500 Short Step, 350, NV4500, EBL flash ECU. Vortec heads & roller cam someday... 05 Jeep Wrangler Unlimited. 3” lift & 6-speed 02 E320 the insurance total “free car” 13 Tahoe LTZ

08-14-2005, 07:22 AM	#5
70GMCer Senior Member Join Date: Apr 2005 Location: Joppa, Maryland Posts: 4,408	I bought my engine harness from MotherTruckers and got the HEI upgrade with it. He's the least expensive I found, and the harness fit like a glove and looks great. I don't think there is any difference between SBC & BBC engine or dash harnesses. There is a difference between an auto or manual trans engine harness though. Mine was a manual and when I ordered the harness, was asked if it was a manual or auto trans. __________________ 1997 GMC Sierra Ext 1965 Mustang

08-14-2005, 08:48 AM	#6
mplex2000 Registered User Join Date: Jul 2005 Location: DFW Posts: 463	Does anybody know where to get the terminals themselves? (The ones inside the firewall plugs?) About 13 years ago I built a 66 Dart, and it used the same terminals. I searched everywhere and finally found them at a local parts shop. That shop went of out business several years ago :/ I've drawn up a new pinout for completely new underhood harnesses. Buying them is so damn expensive, you're only getting about $20 worth of parts for $200+ ... I just can't do it :P My new harness integrates a pair of relays for the headlights, a rad fan relay, hei, internal regulated alt, and a remote starter solenoid. I'm ready to get it made but..I need those damn terminals!

08-14-2005, 01:23 PM	#7
70GMCer Senior Member Join Date: Apr 2005 Location: Joppa, Maryland Posts: 4,408	Try this site for the terminals. I just found this site... http://americanautowire.com/index.cfm __________________ 1997 GMC Sierra Ext 1965 Mustang

08-14-2005, 09:44 PM	#8
jhow66 Registered User Join Date: Jun 2002 Location: Knoxville Tenn. Posts: 3,058	Napa has them. __________________ 56 Chevy Bel-Air 2dr. HT (purchased new) 71 Chevy Cheyenne SWB PU (502HO) 65 GMC short bed step--work in progress and my gofer

08-15-2005, 12:04 AM	#9
mplex2000 Registered User Join Date: Jul 2005 Location: DFW Posts: 463	Thanks for the link, they have them!!!! Sweeeet!!! I'm so glad...now I can rewire the entire truck with all the add-on goodies for $100 (actually might be less than that!!). You guys rock! -Chris

08-15-2005, 07:47 AM	#10
70c10 67-72 Addict! Join Date: Feb 2002 Location: The TAX State! Posts: 7,857	Steve, thanks for that link! __________________ Jim 1970 C/10 Fleetside w/Ghost Flames Lowered 4.5" front and 4" rear (Raked) 355/350 Turbo w/shift kit 10" Redneck Performance Verter w/2500 stall Hooker Super Comps part#2808-1 Performer RPM Air-Gap 12 Bolt w/3:73 gears- Eaton Posi Comp Cams XE262 with 1.6 Crane Energizers, Road Demon 625 and Brodix IK 180 heads Last edited by 70c10; 08-15-2005 at 07:54 AM.



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