HEI firing question and problem... - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Novaguy73 · 03-30-2006, 07:48 PM

I have a 72 chevy C-10 i just put a new HEI in. I put the 12 volt source for the coil pack on the "radio" spot in the fuse box. It didnt fire. I then switched it to a constant 12v source and it fired right up. I then switched it back to the radio spot and IT FIRED right back up. Then i let it sit for a few minutes and it wouldnt fire again!! Swith it back to the constant 12v source and it fires right off and then back to the radio spot and it fires again, then after 5 minutes or so it wont fore again. my only problem with it being on the constant source is the it wont shut off...thats a problem. The good side is that it runs like a CHAMP. Im talking it cleaned up the idle and has great throttle response and acceleration compared to the old points dist. Could it be a bad battery? i dont know what else it could be... any ideas?

13lazer · 03-30-2006, 09:19 PM

your tan off white wire that originally went to your coil should be bypassed. run a 10 or 13 gauge pink or brown (cant remember) to the batt side on your hei. get rid of the resistance wire, but use that circuit. the unfused ign spot in your panel is where your tach harness would go. your engine harness is the other half away from the headlight/ generator harness. you can remove every wire harness from your truck in under 1/2 hour, thats the best way fix these trucks' electrical problems. all of the plugs only go together one way. i hope this helps

jrb71c20 · 03-30-2006, 09:35 PM

http://67-72chevytrucks.com/vboard/s...ad.php?t=17403
http://67-72chevytrucks.com/vboard/s...ad.php?t=13698

Those are what I used when I did it a couple weeks ago from the FAQ section

Longhorn Man · 03-30-2006, 09:43 PM

The problem is, the radio is on the acc circuit, not ignition circuit.
Acc is not powered when the engine is being cranked. Your heater, turn signals, radio, wipers...they all turn off when you crank the engine.
Run that wire to the IGN UNFUSED plug on your fuse box, and you'll be runnin great, starting up right, and shutting off when you turn off the ignition.

red71cheyenne · 03-31-2006, 12:42 AM

I used Shifty's write up in the FAQ and replaced the old resistance wire with a wire and plug off of a newer HEI equipped rig. Napa sells the terminals for $.69 and the only tough part was getting the old terminal out. NOTE: Squeeze the terminal top to bottom and then pull from the outside. It pops right out. Replace terminal with new wire, and off you go! Jeff.

03-30-2006, 07:48 PM	#1
Novaguy73 Registered User Join Date: Oct 2005 Location: Waterloo, Ia Posts: 73	HEI firing question and problem... I have a 72 chevy C-10 i just put a new HEI in. I put the 12 volt source for the coil pack on the "radio" spot in the fuse box. It didnt fire. I then switched it to a constant 12v source and it fired right up. I then switched it back to the radio spot and IT FIRED right back up. Then i let it sit for a few minutes and it wouldnt fire again!! Swith it back to the constant 12v source and it fires right off and then back to the radio spot and it fires again, then after 5 minutes or so it wont fore again. my only problem with it being on the constant source is the it wont shut off...thats a problem. The good side is that it runs like a CHAMP. Im talking it cleaned up the idle and has great throttle response and acceleration compared to the old points dist. Could it be a bad battery? i dont know what else it could be... any ideas? __________________ -73' Nova 350 5-speed 9"rear, Runs 11's drives anywhere... -72' C10 350 Auto 12 bolt, runs 19's?? drives to work!

03-30-2006, 09:19 PM	#2
13lazer 13lazers' blazers Join Date: Jul 2005 Location: San Pedro, CA Posts: 152	Re: HEI firing question and problem... your tan off white wire that originally went to your coil should be bypassed. run a 10 or 13 gauge pink or brown (cant remember) to the batt side on your hei. get rid of the resistance wire, but use that circuit. the unfused ign spot in your panel is where your tach harness would go. your engine harness is the other half away from the headlight/ generator harness. you can remove every wire harness from your truck in under 1/2 hour, thats the best way fix these trucks' electrical problems. all of the plugs only go together one way. i hope this helps

03-30-2006, 09:35 PM	#3
jrb71c20 Registered User Join Date: Mar 2005 Location: Claremore, OK Posts: 486	Re: HEI firing question and problem... http://67-72chevytrucks.com/vboard/s...ad.php?t=17403 http://67-72chevytrucks.com/vboard/s...ad.php?t=13698 Those are what I used when I did it a couple weeks ago from the FAQ section

03-30-2006, 09:43 PM	#4
Longhorn Man its all about the +6 inches Join Date: Jan 2001 Location: Hilliard Ohio Posts: 2,693	Re: HEI firing question and problem... The problem is, the radio is on the acc circuit, not ignition circuit. Acc is not powered when the engine is being cranked. Your heater, turn signals, radio, wipers...they all turn off when you crank the engine. Run that wire to the IGN UNFUSED plug on your fuse box, and you'll be runnin great, starting up right, and shutting off when you turn off the ignition.

03-31-2006, 12:42 AM	#5
red71cheyenne Back in the sticks Join Date: Jan 2001 Location: Fordland, MO Posts: 3,188	Re: HEI firing question and problem... I used Shifty's write up in the FAQ and replaced the old resistance wire with a wire and plug off of a newer HEI equipped rig. Napa sells the terminals for $.69 and the only tough part was getting the old terminal out. NOTE: Squeeze the terminal top to bottom and then pull from the outside. It pops right out. Replace terminal with new wire, and off you go! Jeff. __________________ 1971 Cheyenne C-10 w/700R4 and Tuned Port Injection 1969 K5 Blazer w/Tuned Port 2010 2SS/RS Flaming Orange Camaro 2011 K1500 Suburban 2014 K1500 Pickup 2008 Nissan Altima? The wifes' hoopty



Register or Log In To remove these advertisements.

Register or Log In To remove these advertisements.