Hei to unfused ignition, how big a fuse for inline fuse ? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

RainFade · 12-12-2004, 09:26 PM

At some point one of the two dread previous owners has converted my truck to HEI... I use the word converted a bit loosely as it is a kludge of the 10th order of kludgedom

I have picked up all the pieces and parts to wire into the unfused ignition on my fuse block but one thing I haven't seen in the FAQ or by searching was how many amp a fuse is best for the inline fuse I plan to wire to this ?

TIA

Brian

67ChevyC10Stepside · 12-12-2004, 09:48 PM

i didnt use any fuse....

Sweet72 · 12-12-2004, 09:49 PM

Why do you want to install a fuse when GM didn't use one for the ign. primary wire?

Longhorn Man · 12-12-2004, 09:54 PM

Honestly, i've never used one either.

RainFade · 12-12-2004, 10:07 PM

Well to be honest I am a total newbie to all things bow tie and so searched the board and found an excellent FAQ by a 'longhorn man'

the hei faq

In this thread someone asked if they'd need an inline fuse and he said yes, not knowing anything about the subject and being anal retentive I thought yeah that makes sense if the module were to present a dead short a fuse is easier to replace than a bunch of wire with it's insulation melted off

I'll just wire some 10 gauge (the wire on the hei looks like 10 or is this overkill) directly to the fuse block and be happy then.

Thanks again,

Brian

Longhorn Man · 12-12-2004, 10:09 PM

lol, yeah, i know it should probably have a fuse, but like I said, i've never done it as of yet.

Tx Firefighter · 12-12-2004, 10:35 PM

Every wire on your truck should be fused. If it's an unfused terminal, it's up to you to add the fuse when you utilize the circuit.

Andy, I know you well enough to say you are smarter than that. Surely there's an inline holder laying around somewhere at your work you could liberate for the HEI in your truck.

Longhorn Man · 12-12-2004, 10:45 PM

Yeah...talk about lazy huh?
I actually have a few spade type fese holders right here....I'll grab one and say "that's for the HEI" and forget about it and then end up buying another.

Procrastination is like masturbation....even though it feels good while doin it, you're just screwing your self.

Blue68 · 12-13-2004, 12:19 AM

10 guage is overkill.

**Stocker** · 12-13-2004, 10:25 AM

Mine is 12 gauge, unfused.

HuggerCST · 12-13-2004, 11:35 AM

I tried using a 30 amp inline fuse on my race car(with HEI) once, and it popped & banged at high RPM (around 5500-6000) for a few laps, then finally blew the fuse. I rewired it without the fuse and it ran great. I'm not sure what you need, maybe a fusible link, or a breaker, but a 30 amp fuse won't do it.

Bill72BB · 12-13-2004, 12:12 PM

I've been using 12 gauge wire with a 5 amp fuse , powering the Hei and Electric choke , no problem's.
I take the fuse out when I need an ignition shut off ,to deter thief's .

HuggerCST · 12-13-2004, 12:36 PM

5 amp? Wow, I don't know how you're doing that, Bill. I'm really confused now,

but then again, it doesn't take much, lol. :p

Fred T · 12-13-2004, 02:28 PM

12 gauge wire and 20 amp fuse is sufficent for most street racers.

dwaite72lnghrn · 12-13-2004, 07:38 PM

I haven't used fuses on HEI I have put in. If you use 10 gauge wire it is larger than the fusible link off the battery so it should not melt before the fusible link. But a fuse would make sense as most other large current accs. use a fuse like AC, Blower and all of the lights. the lighter stuff would use fuses because the wire is much lighter than the fusible link and would burn the harness. The internals of the dizzy are only about 18gauge so you know it is not pulling a lot of current. I haven't put a meter on it to see what it draws but I would say it not a lot.

Sweet72 · 12-13-2004, 08:43 PM

RainFade, check out this link and scroll down to the paragraph "using a inline fuse with your ignition coil". Good info. Fred T was right on the money at recommending the 20 amp fuse. If you don't rev it up too high you can get away with the 1 amp per 1000rpm. formula. Keep a spare module in the glove box anyway.

http://www.centuryperformance.com/mallory/unitest.asp

12-12-2004, 09:26 PM	#1
RainFade Registered User Join Date: Nov 2004 Location: Central Ohio Posts: 215	Hei to unfused ignition, how big a fuse for inline fuse ? At some point one of the two dread previous owners has converted my truck to HEI... I use the word converted a bit loosely as it is a kludge of the 10th order of kludgedom I have picked up all the pieces and parts to wire into the unfused ignition on my fuse block but one thing I haven't seen in the FAQ or by searching was how many amp a fuse is best for the inline fuse I plan to wire to this ? TIA Brian __________________ 71 K20 350/350/205, dealer air, 4" lift, Flowtech,Edel 1406 on 2101, procomp HEI,4.10's, 33x12.50x16.5 BFG MT's on slots. 4 wheel disc brakes. My lame K20 page My lame Eaton disc brake page

12-12-2004, 09:48 PM	#2
67ChevyC10Stepside Registered User Join Date: Mar 2004 Location: Butler PA Posts: 3,032	i didnt use any fuse.... __________________ 67 c-10, 400 SB, TH350, 4.10 gears, Blazer tank,camaro tach, sidemarker fuel fill (soon) WTB: stepside parts, 67 front end parts, 67 small window cab. posi for 3.73 or 4.10 for 12 bolt and 10 bolt.

12-12-2004, 09:49 PM	#3
Sweet72 Registered User Join Date: Nov 2003 Location: Alexandria, VA Posts: 1,534	Why do you want to install a fuse when GM didn't use one for the ign. primary wire? __________________ '72 GMC SWB C1500 Custom, frame-off in progress. 383 SBC, 9:1CR, Comp Cams XE262H, Scat internal balanced crank, Eagle SIR 6" rods, Keith Black dish pistons, Dart Iron Eagle 72/180 heads, Weiand Stealth intake, Stewart stage I water pump, Holley 4bbl vac sec, TH350 with B&M Shift Improver Kit. 12 bolt positraction.

12-12-2004, 10:07 PM	#5
RainFade Registered User Join Date: Nov 2004 Location: Central Ohio Posts: 215	Well to be honest I am a total newbie to all things bow tie and so searched the board and found an excellent FAQ by a 'longhorn man' the hei faq In this thread someone asked if they'd need an inline fuse and he said yes, not knowing anything about the subject and being anal retentive I thought yeah that makes sense if the module were to present a dead short a fuse is easier to replace than a bunch of wire with it's insulation melted off I'll just wire some 10 gauge (the wire on the hei looks like 10 or is this overkill) directly to the fuse block and be happy then. Thanks again, Brian __________________ 71 K20 350/350/205, dealer air, 4" lift, Flowtech,Edel 1406 on 2101, procomp HEI,4.10's, 33x12.50x16.5 BFG MT's on slots. 4 wheel disc brakes. My lame K20 page My lame Eaton disc brake page

12-12-2004, 10:35 PM	#7
Tx Firefighter Watch out for your cornhole ! Join Date: Jun 2003 Location: Azle, Texas Posts: 14,162	Every wire on your truck should be fused. If it's an unfused terminal, it's up to you to add the fuse when you utilize the circuit. Andy, I know you well enough to say you are smarter than that. Surely there's an inline holder laying around somewhere at your work you could liberate for the HEI in your truck. __________________ I'm on the Instagram- @Gearhead_Kevin

12-12-2004, 09:54 PM	#4
Longhorn Man its all about the +6 inches Join Date: Jan 2001 Location: Hilliard Ohio Posts: 2,690	Honestly, i've never used one either.

12-12-2004, 10:09 PM	#6
Longhorn Man its all about the +6 inches Join Date: Jan 2001 Location: Hilliard Ohio Posts: 2,690	lol, yeah, i know it should probably have a fuse, but like I said, i've never done it as of yet.

12-12-2004, 10:45 PM	#8
Longhorn Man its all about the +6 inches Join Date: Jan 2001 Location: Hilliard Ohio Posts: 2,690	Yeah...talk about lazy huh? I actually have a few spade type fese holders right here....I'll grab one and say "that's for the HEI" and forget about it and then end up buying another. Procrastination is like masturbation....even though it feels good while doin it, you're just screwing your self.

12-13-2004, 12:19 AM	#9
Blue68 Registered User Join Date: Apr 2000 Location: Frisco, Tx, USA Posts: 606	10 guage is overkill. __________________ http://home.comcast.net/~r.landrum/w...tos.html-.html '68 C-10 LWB, '98 Z-71 350 w/accessories (Serpentine), Edelbrock Performer, Edelbrock 1405 (600cfm) carb, GM HEI, CompCam Extreme 4x4 roller cam, Thorley Headers, Carter Electric Fuel Pump, Vintage Air, 700r4, 3.73, disc brakes and power steering upgrades.

12-13-2004, 10:25 AM	#10
Stocker 20' Daredevil (Ret) Join Date: May 2003 Location: Jefferson State Posts: 13,722	Mine is 12 gauge, unfused. __________________ - Mike - 1972 K20 LWB 350/350/205 RIP El Jay

12-13-2004, 11:35 AM	#11
HuggerCST Registered User Join Date: Jul 2001 Location: North Louisiana Posts: 4,501	I tried using a 30 amp inline fuse on my race car(with HEI) once, and it popped & banged at high RPM (around 5500-6000) for a few laps, then finally blew the fuse. I rewired it without the fuse and it ran great. I'm not sure what you need, maybe a fusible link, or a breaker, but a 30 amp fuse won't do it. __________________ Wynne 70 CST short fleet Hugger orange & white, 350/350, ps, pb, air, tilt, tach/vac/speedwarning, original buckets, AM/FM, oak bed floor, shoulder belts, 3.5"/5.5" drop, 20" American Racing VN425s. Build thread 53 Chevy shortbed 69 Camaro Click here to subscribe Chevy GMC International Truck Club Louisiana Charter Member http://www.louisianaclassictruckclub.com

12-13-2004, 12:12 PM	#12
Bill72BB Thats the Hillbilly way Join Date: Jul 2001 Location: Torrance,Ca Posts: 5,979	I've been using 12 gauge wire with a 5 amp fuse , powering the Hei and Electric choke , no problem's. I take the fuse out when I need an ignition shut off ,to deter thief's . __________________ BILL Torrance Calif 90504 Member DUF Club Member Old Farts Club 72 3/4ton Custom Camper BB402/400 trans Dynomax Cerama-coat headers , Hei distributor ,Edelbrock 1411 air,ps,pb,leafsprings ,98 chevy 60/40 seat,S10 shoulder belts tilt,3.54 Dana 60 rear. 16" Eagle wheels with LT265/75 16 tires,Gaylord Lid,H4 headlights with 100W relay conversion. " If I knew I was going to live this long I would have taken better care of myself " Marriage changes passion...suddenly you're in bed with a relative. A GUY'S PRAYER.... Lord, I pray for a nympho with huge boobs who owns a liquor store and likes to fish and hunt and has a Harley .Amen ,

12-13-2004, 12:36 PM	#13
HuggerCST Registered User Join Date: Jul 2001 Location: North Louisiana Posts: 4,501	5 amp? Wow, I don't know how you're doing that, Bill. I'm really confused now, but then again, it doesn't take much, lol. :p __________________ Wynne 70 CST short fleet Hugger orange & white, 350/350, ps, pb, air, tilt, tach/vac/speedwarning, original buckets, AM/FM, oak bed floor, shoulder belts, 3.5"/5.5" drop, 20" American Racing VN425s. Build thread 53 Chevy shortbed 69 Camaro Click here to subscribe Chevy GMC International Truck Club Louisiana Charter Member http://www.louisianaclassictruckclub.com

12-13-2004, 02:28 PM	#14
Fred T Cantankerous Geezer Join Date: Aug 2002 Location: Bel Aire, KS Posts: 6,264	12 gauge wire and 20 amp fuse is sufficent for most street racers. __________________ Fred There is no such thing as too much cam...just not enough engine.

12-13-2004, 07:38 PM	#15
dwaite72lnghrn Registered User Join Date: Jun 2002 Location: central pa Posts: 1,525	I haven't used fuses on HEI I have put in. If you use 10 gauge wire it is larger than the fusible link off the battery so it should not melt before the fusible link. But a fuse would make sense as most other large current accs. use a fuse like AC, Blower and all of the lights. the lighter stuff would use fuses because the wire is much lighter than the fusible link and would burn the harness. The internals of the dizzy are only about 18gauge so you know it is not pulling a lot of current. I haven't put a meter on it to see what it draws but I would say it not a lot. __________________ 72 longhorn c30 502BB/th400/fact air/4.11rear/ custom camper 72 bug(the better half's) under reconstruction 2009 HHR aqua blue 71 GMC k20 350/sm465 2009 Chevy hd3500 6.6 Victory Red crew cab dually Dave & Jeanne



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12-13-2004, 08:43 PM	#16
Sweet72 Registered User Join Date: Nov 2003 Location: Alexandria, VA Posts: 1,534	RainFade, check out this link and scroll down to the paragraph "using a inline fuse with your ignition coil". Good info. Fred T was right on the money at recommending the 20 amp fuse. If you don't rev it up too high you can get away with the 1 amp per 1000rpm. formula. Keep a spare module in the glove box anyway. http://www.centuryperformance.com/mallory/unitest.asp __________________ '72 GMC SWB C1500 Custom, frame-off in progress. 383 SBC, 9:1CR, Comp Cams XE262H, Scat internal balanced crank, Eagle SIR 6" rods, Keith Black dish pistons, Dart Iron Eagle 72/180 heads, Weiand Stealth intake, Stewart stage I water pump, Holley 4bbl vac sec, TH350 with B&M Shift Improver Kit. 12 bolt positraction. Last edited by Sweet72; 12-13-2004 at 08:47 PM.

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