wiring......for dummies.... - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Coach529 · 06-13-2014, 01:20 AM

OK, so Henry (1949 3600) needs some new wiring!!

I am using part of the original harness and fuse block.

Installing a SBC with an HEI. Found this diagram online and it makes sense. Any input?

fabguy · 06-13-2014, 06:53 AM

Just make sure that you have power all the time on the ignition post even when the key is trying to start. If not it will be hard to start.

1project2many · 06-13-2014, 08:20 AM

Quote:

Just make sure that you have power all the time on the ignition post even when the key is trying to start. If not it will be hard to start.

That's what the second connection to the starter solenoid is for. But make sure your starter has this connection. Many don't these days.

Larry58gmc · 06-13-2014, 09:39 AM

Is that 15A fuse necessary for HEI ignition. I'm using HEI on my 58 gmc with sbc now but I don't have a fuse in line. I'm also using a one wire set up on an alternator. Larry

mr48chev · 06-13-2014, 11:52 AM

I've never run a fuse to an Hei but don't see why it would hurt. 15 amps may be on the low side though.

Fabguy makes a good point. Some of the switches on these trucks don't send power to the IGN post when the truck is cranking as they rely on the resistor bypass wire to send power to the coil when cranking the engine. I can't remember what rig but I ran into one that would fire when you let off the key and it was on ign if everything was right and we had to hook up the bypass wire to get it to work. If you have 12V + to the distributor when cranking the engine with the starter no problem.

OrrieG · 06-13-2014, 11:54 AM

Make sure the battery to switch wire has a fusible link or fuse.

DransportGarage · 06-13-2014, 12:57 PM

Quote:

Originally Posted by Larry58gmc

Is that 15A fuse necessary for HEI ignition. I'm using HEI on my 58 gmc with sbc now but I don't have a fuse in line. I'm also using a one wire set up on an alternator. Larry

Only if you don't want to burn up your wiring harness and/or truck

. All it takes is to have your battery connected, pull that wire off the distributor and let it touch the manifold.

Larry58gmc · 06-13-2014, 06:03 PM

My 58 has 12V on the ignition as soon as you turn the switch on. Coach529's 49 may not be that way. When I wired my HEI I used the resistor lead which came off the ignition position of the switch. I removed all the resistor wire and went direct to the switch. I want to put a fuse on it but maybe from the one wire alternator back to where it connect to the system. If you think 15A is a little small how big do you think it should be.

Coach529, are you using an alternator or generator.Larry

Coach529 · 06-13-2014, 08:12 PM

Thanks for all the info guys. I twist wires everyday, but this vehicle stuff has me confused.

Coach529 · 06-13-2014, 08:15 PM

Quote:

Originally Posted by Larry58gmc

My 58 has 12V on the ignition as soon as you turn the switch on. Coach529's 49 may not be that way. When I wired my HEI I used the resistor lead which came off the ignition position of the switch. I removed all the resistor wire and went direct to the switch. I want to put a fuse on it but maybe from the one wire alternator back to where it connect to the system. If you think 15A is a little small how big do you think it should be.

Coach529, are you using an alternator or generator.Larry

Larry, I am running an alternator.

DransportGarage · 06-13-2014, 11:16 PM

Quote:

Originally Posted by DransportGarage

Only if you don't want to burn up your wiring harness and/or truck

. All it takes is to have your battery connected, pull that wire off the distributor and let it touch the manifold.

Oops, I forgot...and have the key on.

miknjan · 06-15-2014, 03:55 PM

Don't forget the fusible link or inline fuses. Once you let the smoke out of the wires, its real hard to get back it!

06-13-2014, 01:20 AM	#1
Coach529 Registered User Join Date: Nov 2012 Location: Post Falls, Idaho Posts: 1,757	wiring......for dummies.... OK, so Henry (1949 3600) needs some new wiring!! I am using part of the original harness and fuse block. Installing a SBC with an HEI. Found this diagram online and it makes sense. Any input? __________________ 1949 Chevy 3600 "Adventures of Henry" http://smu.gs/QOlhWY

06-13-2014, 06:53 AM	#2
fabguy Elev8r Man Join Date: Aug 2010 Location: Glendora, CA Posts: 835	Re: wiring......for dummies.... Just make sure that you have power all the time on the ignition post even when the key is trying to start. If not it will be hard to start. __________________ 1955.2 C4 Carry-all / Suburban ---> 55.2 Build Thread!! 1958 Fleetside SWB ---> 58 Fleetside Build thread 1939 2 door sedan *My F.B. project page.*

06-13-2014, 09:39 AM	#4
Larry58gmc Registered User Join Date: Jun 2014 Location: Richmond Virginia Posts: 8	Re: wiring......for dummies.... Is that 15A fuse necessary for HEI ignition. I'm using HEI on my 58 gmc with sbc now but I don't have a fuse in line. I'm also using a one wire set up on an alternator. Larry

06-13-2014, 11:52 AM	#5
mr48chev Registered User Join Date: Jul 2007 Location: Toppenish, WA Posts: 15,413	Re: wiring......for dummies.... I've never run a fuse to an Hei but don't see why it would hurt. 15 amps may be on the low side though. Fabguy makes a good point. Some of the switches on these trucks don't send power to the IGN post when the truck is cranking as they rely on the resistor bypass wire to send power to the coil when cranking the engine. I can't remember what rig but I ran into one that would fire when you let off the key and it was on ign if everything was right and we had to hook up the bypass wire to get it to work. If you have 12V + to the distributor when cranking the engine with the starter no problem. __________________ Founding member of the too many projects, too little time and money club. My ongoing truck projects: 48 Chev 3100 that will run a 292 Six. 71 GMC 2500 that is getting a Cad 500 transplant. 77 C 30 dualie, 454, 4 speed with a 10 foot flatbed and hoist. It does the heavy work and hauls the projects around.

06-13-2014, 11:54 AM	#6
OrrieG Registered User Join Date: Jun 2006 Location: Idaho Posts: 8,800	Re: wiring......for dummies.... Make sure the battery to switch wire has a fusible link or fuse. __________________ 1959 Chevy Short Fleetside w/ 74 4WD drive train (current project) OrrieG Build Thread 1964 Chevelle Malibu w/ 355-350TH (daily driver) Helpful AD and TF Manual Site Old Car Manual Project

06-13-2014, 06:03 PM	#8
Larry58gmc Registered User Join Date: Jun 2014 Location: Richmond Virginia Posts: 8	Re: wiring......for dummies.... My 58 has 12V on the ignition as soon as you turn the switch on. Coach529's 49 may not be that way. When I wired my HEI I used the resistor lead which came off the ignition position of the switch. I removed all the resistor wire and went direct to the switch. I want to put a fuse on it but maybe from the one wire alternator back to where it connect to the system. If you think 15A is a little small how big do you think it should be. Coach529, are you using an alternator or generator.Larry

06-13-2014, 08:12 PM	#9
Coach529 Registered User Join Date: Nov 2012 Location: Post Falls, Idaho Posts: 1,757	Re: wiring......for dummies.... Thanks for all the info guys. I twist wires everyday, but this vehicle stuff has me confused. __________________ 1949 Chevy 3600 "Adventures of Henry" http://smu.gs/QOlhWY

06-15-2014, 03:55 PM	#12
miknjan Registered User Join Date: Jan 2008 Location: Orting WA. Posts: 16	Re: wiring......for dummies.... Don't forget the fusible link or inline fuses. Once you let the smoke out of the wires, its real hard to get back it!



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