Burnt out two coils in one day???Help! - The 1947 - Present Chevrolet & GMC Truck Message Board Network

jdhcth · 03-08-2007, 01:26 PM

This is old school points distributor / external coil.

Warm start....ran for a couple seconds then died. No fire from the coil after that. Changed out the coil and Voltage Regulator(which was actin' weird) and that fixed it. Drove home.....20 minutes, got home stopped it...started....ran a few seconds...died, burned out that coil. What's the deal????

What voltage is supposed to be supplied to the coil when the ignition switch is in the "on" position? Not full 12 volts I believe, but that's what I have. Is my resistor wire bad?

Thanks,
JD

70rs/ss · 03-08-2007, 02:25 PM

Sounds like it's overcharging, maybe have the alternator checked as well as the voltage regulator.

NPilot1975 · 03-08-2007, 02:47 PM

Do you still have the ceramic resistor installed? I have never used any thing but HEI or newer, but know they are required for the older ignition systems. Should be mounted on the firewall behind the distributor and is white.

jdhcth · 03-08-2007, 03:27 PM

Thanks, I'l check that ceramin resistor out. But that means I should not have full 12v at the coil. What is the normal "ignition on" voltage at the + coil?

JD

67ChevyRedneck · 03-08-2007, 03:42 PM

I think it's 8V?

3/4tonterror · 03-08-2007, 03:42 PM

sounds like the ceramic resister.

68speedalert · 03-08-2007, 03:52 PM

I don't believe there is a ceramic resister. It has something called a resistance wire.

When you measure the voltage, you have to measure it with a load, other than the meter. If the coil is open, there is no load on the wire.

If you have a 12 volt test light, that will do. Hold the light on the wire w/key on, THEN measure the voltage. I believe that 67ChevyRedNeck is right, about 8 volts.

70rs/ss · 03-08-2007, 04:07 PM

Yeah the coil wire has the resistance built in, and the voltage to the coil from that wire should be 7-8, I think. If you rewired it and are running 12v to it that's the problem, if not check to see if you have the coil wired correctly (+,-) to the correct side (shouldn't burn it up but will hurt the performance a little).

regal8r · 03-08-2007, 04:30 PM

switch to HEI

Big Block · 03-08-2007, 05:30 PM

The yellow wire is a "resistive wire" and should have 8 volts on it. If you switch to HEI you'll need 12 volts to make it work properly.

regal8r · 03-08-2007, 05:40 PM

Quote:

Originally Posted by Big Block

The yellow wire is a "resistive wire" and should have 8 volts on it. If you switch to HEI you'll need 12 volts to make it work properly.

thats not that hard though. IIRC just take a 12ga wire from battery to B+ on the distributor...

67ChevyRedneck · 03-08-2007, 05:51 PM

You don't want to run a wire from the battery to the HEI. It will have constant power, which you don't want.

One of the "proper" ways to do it would be to run a wire from the IGN UNFUSED Spade connecter in the fuse block to the dizzy.

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

regal8r · 03-08-2007, 05:59 PM

ahhh, yes...thast what i meant chevy. thanks for the correction

68speedalert · 03-08-2007, 09:09 PM

Changing to HEI is a good idea. But.....if you want to keep your points, you need to find the problem.

How do you know the coil is burnt? Just because no spark?

It's pretty rare that these coils burn out, much less 2 of them. You need to pull your cap and check the wire running from the coil to the points VERY closely. If it has a bare spot that is touching metal (a ground), it will make your spark quit and, eventually, burn out the coil.

More than likely you have a bad points and condenser. They need to be changed/adjusted regularly. Get a good set; I like them from NAPA. They have a points set that have a hole in the middle of the contact. They seemed to last longer than without the hole.

Also, they may try to sell you a 'uniset' points set. This has the condenser and points in one assembly. Stay away from them; change yours to the individual style if it has the uniset.

jdhcth · 03-08-2007, 10:53 PM

Thanks guys.

Speedalert, I just figured it was burning the coils up cause I quit gettin' spark from them and instantly when I put a new one in I got spark again. They never got hot or smelled burnt though, they'd just quit makin' fire.

I'm goin' with a HEI and a one wire Alt(tired of replacing voltage regs). If that doesn't do it

then a new wiring harness may be the ticket.

thanks again all,

JD

long71 · 03-09-2007, 12:02 AM

check the ground from the alternator. had the same problem in my boat (ford 460) i noticed the voltmeter reading about 15 volts and seconds later i had a smoking hot coil and a broke down boat. after a new alternator and coil same thing happened (this time not on the water) turns out it was the ground wire from the alternator, it had corroded and lost its connection. replaced that and good as new and the bastards wouldnt take back the alternator they told me i needed

jdhcth · 03-19-2007, 01:13 PM

OK, as usual you guys are right, I'm not burning out coils. It seems when it's hot it won't start up again. SO I replaced the condenser, this seemed to have worked. BUT, today i drive it to work, turn it off, try to restart....it just cranks but wont fire up. I let it cool down, fired right up.

What causes this? I'm stubborn and still using my points dizzy, I will upgrade to HEI but I want to make sure that will solve this problem.

Thanks guys,
JD

Richard H. · 03-19-2007, 01:27 PM

First off the coil does not care if you give it 6v or 13.6 , but your points and condenser sure do and that is what the ballast resistor is for and for more fun you can go to Napa and get a 12v coil with an internal resistor. The hei is not a bad idea for you especially when you think about the made in mex. label on the back of the condenser.

68speedalert · 03-19-2007, 01:42 PM

So you didn't change the points &/or check the dwell? You've GOT TO DO BOTH!!!!

Also, check the ground wire going from the dizzy housing (vacuum advance bolt) to points plate.

HAVCEL · 11-30-2014, 09:32 PM

This is what I get for reading. This is my first post and I want to Thank Everyone for posting on this thread. I was having a bit of a problem in getting spark. Just want to see the engine turn over and start before putting the money where it doesn't belong. HEI is the way to go and I'll upgrade later. But as long as I know where to look to get spark, because of this thread. Thanks again all. H.

dmack91 · 11-30-2014, 11:14 PM

Nice to see a 7 year old thread helping out.

Welcome to the forum.

HAVCEL · 12-01-2014, 07:55 AM

I Was a Moderator with an FTA site. Some newbies asked questions instead of reading old threads & posts. The answer is out there somewhere. Thanks dmack91 for the welcome.

03-08-2007, 01:26 PM	#1
jdhcth Registered User Join Date: Dec 2005 Location: Houston, TX Posts: 51	Burnt out two coils in one day???Help! This is old school points distributor / external coil. Warm start....ran for a couple seconds then died. No fire from the coil after that. Changed out the coil and Voltage Regulator(which was actin' weird) and that fixed it. Drove home.....20 minutes, got home stopped it...started....ran a few seconds...died, burned out that coil. What's the deal???? What voltage is supposed to be supplied to the coil when the ignition switch is in the "on" position? Not full 12 volts I believe, but that's what I have. Is my resistor wire bad? Thanks, JD

03-08-2007, 02:25 PM	#2
70rs/ss Registered User Join Date: Dec 2004 Location: Northern AZ Posts: 7,271	Re: Burnt out two coils in one day???Help! Sounds like it's overcharging, maybe have the alternator checked as well as the voltage regulator.

03-08-2007, 02:47 PM	#3
NPilot1975 Senior Member Join Date: Aug 2002 Location: Plymouth, MA Posts: 891	Re: Burnt out two coils in one day???Help! Do you still have the ceramic resistor installed? I have never used any thing but HEI or newer, but know they are required for the older ignition systems. Should be mounted on the firewall behind the distributor and is white. __________________ 1972 Blazer body...need to get a thread started for the rest of the story

03-08-2007, 03:27 PM	#4
jdhcth Registered User Join Date: Dec 2005 Location: Houston, TX Posts: 51	Re: Burnt out two coils in one day???Help! Thanks, I'l check that ceramin resistor out. But that means I should not have full 12v at the coil. What is the normal "ignition on" voltage at the + coil? JD

03-08-2007, 03:42 PM	#5
67ChevyRedneck Hittin E-Z Street on Mud Tires Join Date: Nov 2004 Location: Greenville, SC Posts: 23,090	Re: Burnt out two coils in one day???Help! I think it's 8V? __________________ Jesse James 1967 C10 SWB Stepside: 350/700R4/3.73 1965 Ford Mustang: 289/T5-5spd/3.25 Trac-Loc 1968 Pontiac Firebird: Project Fire Chicken! 2015 Silverado Double Cab 5.3L Z71 2001 Jeep Wrangler Sport 4.0L 5spd 2020 Chevrolet Equinox Premium 2.0L Turbo 2011 Mustang V6 ~ Wife's ride American Born, Country by the Grace of God 1967 CST Shop Truck Rebuild! My 1967 C-10 Build Thread My Vintage Air A/C Install Project "On a Dime" Trying my hand at Home Renovation! 1965 Mustang Modifications!

03-08-2007, 03:42 PM	#6
3/4tonterror Registered User Join Date: Dec 2006 Location: jaffrey,NH Posts: 325	Re: Burnt out two coils in one day???Help! sounds like the ceramic resister.

03-08-2007, 03:52 PM	#7
68speedalert Semi-Senior Member Join Date: Feb 2003 Location: Washington, MO Posts: 390	Re: Burnt out two coils in one day???Help! I don't believe there is a ceramic resister. It has something called a resistance wire. When you measure the voltage, you have to measure it with a load, other than the meter. If the coil is open, there is no load on the wire. If you have a 12 volt test light, that will do. Hold the light on the wire w/key on, THEN measure the voltage. I believe that 67ChevyRedNeck is right, about 8 volts. __________________ '68 50th Anniversery LWB Custom Fleetside, '77 305 v-8, turbo 350, factory speed alert (still works), '71 drivetrain w/front discs. Some call it ugly yellow, others call it Ochre '83 Jeep CJ-7, <80,000 miles, original owner '04 Chevy Suburban, 4x4, 2500, 6.0 ltr, Predator Diablo programmer '95 GMC K1500 Extended cab

03-08-2007, 04:07 PM	#8
70rs/ss Registered User Join Date: Dec 2004 Location: Northern AZ Posts: 7,271	Re: Burnt out two coils in one day???Help! Yeah the coil wire has the resistance built in, and the voltage to the coil from that wire should be 7-8, I think. If you rewired it and are running 12v to it that's the problem, if not check to see if you have the coil wired correctly (+,-) to the correct side (shouldn't burn it up but will hurt the performance a little).

03-08-2007, 04:30 PM	#9
regal8r Registered User Join Date: Oct 2006 Location: Lincoln, Nebraska Posts: 112	Re: Burnt out two coils in one day???Help! switch to HEI

03-08-2007, 05:30 PM	#10
Big Block Big Block Join Date: Mar 2005 Location: Durham, N.C. Posts: 1,649	Re: Burnt out two coils in one day???Help! The yellow wire is a "resistive wire" and should have 8 volts on it. If you switch to HEI you'll need 12 volts to make it work properly. Last edited by Big Block; 03-08-2007 at 05:33 PM.

03-08-2007, 05:51 PM	#12
67ChevyRedneck Hittin E-Z Street on Mud Tires Join Date: Nov 2004 Location: Greenville, SC Posts: 23,090	Re: Burnt out two coils in one day???Help! You don't want to run a wire from the battery to the HEI. It will have constant power, which you don't want. One of the "proper" ways to do it would be to run a wire from the IGN UNFUSED Spade connecter in the fuse block to the dizzy. http://67-72chevytrucks.com/vboard/s...ad.php?t=13698 __________________ Jesse James 1967 C10 SWB Stepside: 350/700R4/3.73 1965 Ford Mustang: 289/T5-5spd/3.25 Trac-Loc 1968 Pontiac Firebird: Project Fire Chicken! 2015 Silverado Double Cab 5.3L Z71 2001 Jeep Wrangler Sport 4.0L 5spd 2020 Chevrolet Equinox Premium 2.0L Turbo 2011 Mustang V6 ~ Wife's ride American Born, Country by the Grace of God 1967 CST Shop Truck Rebuild! My 1967 C-10 Build Thread My Vintage Air A/C Install Project "On a Dime" Trying my hand at Home Renovation! 1965 Mustang Modifications! Last edited by 67ChevyRedneck; 03-08-2007 at 05:53 PM.

03-08-2007, 05:59 PM	#13
regal8r Registered User Join Date: Oct 2006 Location: Lincoln, Nebraska Posts: 112	Re: Burnt out two coils in one day???Help! ahhh, yes...thast what i meant chevy. thanks for the correction

03-08-2007, 09:09 PM	#14
68speedalert Semi-Senior Member Join Date: Feb 2003 Location: Washington, MO Posts: 390	Re: Burnt out two coils in one day???Help! Changing to HEI is a good idea. But.....if you want to keep your points, you need to find the problem. How do you know the coil is burnt? Just because no spark? It's pretty rare that these coils burn out, much less 2 of them. You need to pull your cap and check the wire running from the coil to the points VERY closely. If it has a bare spot that is touching metal (a ground), it will make your spark quit and, eventually, burn out the coil. More than likely you have a bad points and condenser. They need to be changed/adjusted regularly. Get a good set; I like them from NAPA. They have a points set that have a hole in the middle of the contact. They seemed to last longer than without the hole. Also, they may try to sell you a 'uniset' points set. This has the condenser and points in one assembly. Stay away from them; change yours to the individual style if it has the uniset. __________________ '68 50th Anniversery LWB Custom Fleetside, '77 305 v-8, turbo 350, factory speed alert (still works), '71 drivetrain w/front discs. Some call it ugly yellow, others call it Ochre '83 Jeep CJ-7, <80,000 miles, original owner '04 Chevy Suburban, 4x4, 2500, 6.0 ltr, Predator Diablo programmer '95 GMC K1500 Extended cab

03-08-2007, 10:53 PM	#15
jdhcth Registered User Join Date: Dec 2005 Location: Houston, TX Posts: 51	Re: Burnt out two coils in one day???Help! Thanks guys. Speedalert, I just figured it was burning the coils up cause I quit gettin' spark from them and instantly when I put a new one in I got spark again. They never got hot or smelled burnt though, they'd just quit makin' fire. I'm goin' with a HEI and a one wire Alt(tired of replacing voltage regs). If that doesn't do it then a new wiring harness may be the ticket. thanks again all, JD

03-09-2007, 12:02 AM	#16
long71 clean concepts Join Date: Feb 2006 Location: fairfield california Posts: 56	Re: Burnt out two coils in one day???Help! check the ground from the alternator. had the same problem in my boat (ford 460) i noticed the voltmeter reading about 15 volts and seconds later i had a smoking hot coil and a broke down boat. after a new alternator and coil same thing happened (this time not on the water) turns out it was the ground wire from the alternator, it had corroded and lost its connection. replaced that and good as new and the bastards wouldnt take back the alternator they told me i needed



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03-19-2007, 01:13 PM	#17
jdhcth Registered User Join Date: Dec 2005 Location: Houston, TX Posts: 51	Re: Burnt out two coils in one day???Help! OK, as usual you guys are right, I'm not burning out coils. It seems when it's hot it won't start up again. SO I replaced the condenser, this seemed to have worked. BUT, today i drive it to work, turn it off, try to restart....it just cranks but wont fire up. I let it cool down, fired right up. What causes this? I'm stubborn and still using my points dizzy, I will upgrade to HEI but I want to make sure that will solve this problem. Thanks guys, JD

03-19-2007, 01:27 PM	#18
Richard H. Spanked once Join Date: Oct 2006 Location: Intheshop, Indiana Posts: 969	Re: Burnt out two coils in one day???Help! First off the coil does not care if you give it 6v or 13.6 , but your points and condenser sure do and that is what the ballast resistor is for and for more fun you can go to Napa and get a 12v coil with an internal resistor. The hei is not a bad idea for you especially when you think about the made in mex. label on the back of the condenser.

03-19-2007, 01:42 PM	#19
68speedalert Semi-Senior Member Join Date: Feb 2003 Location: Washington, MO Posts: 390	Re: Burnt out two coils in one day???Help! So you didn't change the points &/or check the dwell? You've GOT TO DO BOTH!!!! Also, check the ground wire going from the dizzy housing (vacuum advance bolt) to points plate. __________________ '68 50th Anniversery LWB Custom Fleetside, '77 305 v-8, turbo 350, factory speed alert (still works), '71 drivetrain w/front discs. Some call it ugly yellow, others call it Ochre '83 Jeep CJ-7, <80,000 miles, original owner '04 Chevy Suburban, 4x4, 2500, 6.0 ltr, Predator Diablo programmer '95 GMC K1500 Extended cab

11-30-2014, 09:32 PM	#20
HAVCEL Registered User Join Date: Nov 2014 Location: South Carolina Posts: 2	Re: Burnt out two coils in one day???Help! This is what I get for reading. This is my first post and I want to Thank Everyone for posting on this thread. I was having a bit of a problem in getting spark. Just want to see the engine turn over and start before putting the money where it doesn't belong. HEI is the way to go and I'll upgrade later. But as long as I know where to look to get spark, because of this thread. Thanks again all. H.

11-30-2014, 11:14 PM	#21
dmack91 Registered User Join Date: Jan 2011 Location: Redmond, OR Posts: 754	Re: Burnt out two coils in one day???Help! Nice to see a 7 year old thread helping out. Welcome to the forum. __________________ 68 Chev C20- son has it now 83 K20 - bought from son 70 C20 - in progress

12-01-2014, 07:55 AM	#22
HAVCEL Registered User Join Date: Nov 2014 Location: South Carolina Posts: 2	Re: Burnt out two coils in one day???Help! I Was a Moderator with an FTA site. Some newbies asked questions instead of reading old threads & posts. The answer is out there somewhere. Thanks dmack91 for the welcome.

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