Need Wiring diagramhelp!! - The 1947 - Present Chevrolet & GMC Truck Message Board Network

70GMC_BOB · 10-10-2005, 02:00 PM

My dad and I rebuilt the 350 and got the engine re-installed last weekend in my 72 chev 3/4 ton 2wd truck(w/ HEI). When we initially tried to start it it cranked then backfired and lost all power(no lights or anything). I believe it blew a inline fuse. I need a wiring diagram for the engine for a reference. I do have the wiring diagram for a 69 but do not know if they are the same?

I also need a wiring diagram of a hei modification as it was already installed when I bought the truck.

I am going to start troubleshooting today after work.

I forgot my camera when we installed. I will post pics when it is back at my house.

Thanks
70_GMC_BOB

70GMC_BOB · 10-10-2005, 02:06 PM

I found this post on classic heartbeat with a engine comp. wiring diagram. So now I am looking for the HEI modigfication diagram.

http://www.classicheartbeat.com/foru...wiring+diagram

chickenwing · 10-10-2005, 02:15 PM

I am not aware of any "fixed" way to do the HEI mod. You NEVER know how the PO did it until you unwrap the harness! You only need a keyed 12v supply. Think there is a write up in the FAQ's if you want a good way to do it.

70GMC_BOB · 10-10-2005, 02:19 PM

I found the HEI info on classicheartbeat.com As well. If anyone has a diagram or more info it would be appreciated.

http://www.classicheartbeat.com/forums/showthread.php?
t=3265&highlight=DISTRIBUTER

70GMC_BOB · 10-10-2005, 02:21 PM

Just for the record the engine was at TDC and the distributr was pointing to #1 with the vac. adv. pointing cyl #1. Is htis the correct setup?

10-10-2005, 02:06 PM	#2
70GMC_BOB Registered User Join Date: Jul 2001 Location: Lynnwood, washington Posts: 121	I found this post on classic heartbeat with a engine comp. wiring diagram. So now I am looking for the HEI modigfication diagram. http://www.classicheartbeat.com/foru...wiring+diagram __________________ 1972 chev c20 2wd lwb 350v8/th350. (dad's)1970 gmc longstep (9ft commercial bed), 1 ton, 2wd, 350/th400. Last edited by 70GMC_BOB; 10-10-2005 at 02:07 PM.

10-10-2005, 02:19 PM	#4
70GMC_BOB Registered User Join Date: Jul 2001 Location: Lynnwood, washington Posts: 121	I found the HEI info on classicheartbeat.com As well. If anyone has a diagram or more info it would be appreciated. http://www.classicheartbeat.com/forums/showthread.php? t=3265&highlight=DISTRIBUTER __________________ 1972 chev c20 2wd lwb 350v8/th350. (dad's)1970 gmc longstep (9ft commercial bed), 1 ton, 2wd, 350/th400.

10-10-2005, 02:21 PM	#5
70GMC_BOB Registered User Join Date: Jul 2001 Location: Lynnwood, washington Posts: 121	Just for the record the engine was at TDC and the distributr was pointing to #1 with the vac. adv. pointing cyl #1. Is htis the correct setup? __________________ 1972 chev c20 2wd lwb 350v8/th350. (dad's)1970 gmc longstep (9ft commercial bed), 1 ton, 2wd, 350/th400.

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10-10-2005, 02:00 PM	#1
70GMC_BOB Registered User Join Date: Jul 2001 Location: Lynnwood, washington Posts: 121	Need Wiring diagramhelp!! My dad and I rebuilt the 350 and got the engine re-installed last weekend in my 72 chev 3/4 ton 2wd truck(w/ HEI). When we initially tried to start it it cranked then backfired and lost all power(no lights or anything). I believe it blew a inline fuse. I need a wiring diagram for the engine for a reference. I do have the wiring diagram for a 69 but do not know if they are the same? I also need a wiring diagram of a hei modification as it was already installed when I bought the truck. I am going to start troubleshooting today after work. I forgot my camera when we installed. I will post pics when it is back at my house. Thanks 70_GMC_BOB __________________ 1972 chev c20 2wd lwb 350v8/th350. (dad's)1970 gmc longstep (9ft commercial bed), 1 ton, 2wd, 350/th400.

10-10-2005, 02:15 PM	#3
chickenwing Lovin' Life in Miss.! Join Date: Mar 2004 Location: Puckett, Mississippi Posts: 1,937	I am not aware of any "fixed" way to do the HEI mod. You NEVER know how the PO did it until you unwrap the harness! You only need a keyed 12v supply. Think there is a write up in the FAQ's if you want a good way to do it.



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