No Spark from coil, very confused!

[Twilightoptics]

When I bought my '67 she didn't run. Didn't have spark from the coil. Replaced coil. Still no spark. It did have power to it. Replaced the condensor in the distributor. Then I had spark. Truck ran. Then driving the other day the truck died. I tried to get it started again and the coil literally blew up.

Napa replaced coil for free, and I got a new condensor too, just to be safe. Now, no spark again. Doesn't have a balast resistor either. Bought one. Not sure where to put it on. I have two (that look like original wires) going to the + side of the coil. One yellow, and one tan/brown with very small black hashes like a candy cane almost. Should I only have one wire going to the + of the coil?

In the wire harness that these two coil wires come from, there is a blue, and a green wire that have plugs at the end of them that don't go to anything, what are they for?

I have power to the coil, from the coil to the points. So why don't I have spark from the coil? Coil's good, I would imagine, would be huge dumb luck that a brand new one is bad, but that doesn't explain why replacing the condensor made the truck run before and then the coil blow up.

So confused?!

[HEAVY CHEVY]

If I'm not mistaken the blue wire goes to either your temp sending unit or oil pressure unit.
The green wire will probably be the opposite.
I don't have a coil in mine anymore but I think there should only be one wire the yellow if my memory serves me right.

[Super Chevy]

The tan/brown one should be an 8volt source to the + side of the coil,the yellow wire comes off your starter and is for easy starting,it only provides 12 volts to the coil when you turn the motor over,so these two wires are correct..

SC

[Longhorn Man]

How do your points look?
I am not to familiar with points, so i just kinda say this hoping someone will back me up.

[jhow66]

You need to check voltage to coil with switch on--should be around 8 volts. If more than this it will burn points and cause a no run condition--high voltage causes the point spring to get hot and lose it's tension. The wire from switch to coil is a resistor wire--it may have been replaced a regular wire. ( the resistor wire only goes part of the way to bulk head connector)

[Twilightoptics]

Even with balast resistor on, I have 12 volts going to the coil.

[bobs409]

12 volts is too much. Look at the points and see if the arm is blue from excess heat. Odds are you fried the points.

I went through this problem recently on one of my cars. The original resisitor wire had been replaced with a regular wire. That's a no-no.

A resistor wire is wrapped in cloth. Most I have seen are white with red specks. If you don't have this, you can get one from a junker and splice it in. (that's what I did)

If you add the ballast resistor, it does the same job. It cuts down the voltage. You simply install it somewhere in the wire going to the coil. (most mount on the firewall)

Get that voltage down and replace the points/condensor and I think you'll be fine.

[Randy70C-10]

Get an HEI and do away with the points, much less maintenance.

[Twilightoptics]

My points look as though they are white and speckled. I am confused though because I added the ballast resistor on the incoming lead to the + of the coil..... like you're supposed to. And I still get 12 volts...

[Fast68Chevy]

not supposed to if is stock distributor and coil, gm did not use ballasts, only resistance wire feed from ign switch to + on coil, also mounte dot + coil stud is a yellwo wiure form the R terminal on the start solenoid, and sometimes there is yellow wire coming from the fuse block plug on firewall driver side across the firewall top in the wire gutter, so sometimes there are two yellow wire ends connected to + stud on coil, not always though., but always is the white cloth wrapped resistance feed, and on - coil stud is only the black wire directly over to the distrib base

and if all these wires are there in instaleld where theyre supposed ot be and you stil have points burning up then you probably have a problem in truck and i would go find an HEI distrib off some '75-'80 chevy V-8 of any size cept 366 409 or tall 427 powered vehicle, that has a vacuum advance unit on it and not a flat second plug with 4 pins on opposite side of the distrib base from the feed and ground cap plug, and just swap it real quick.

[jhow66]

Have you checked your wire loom for the resistor wire? It will have stainless steel wire instead of copper. Just unwind tape and see. Also check starter to see if yellow wire ("R" post) is dead (no voltage) when switch is on (should be live only when switch is in start position). If yellow wire is live with switch on your soleniod is bad. This will cause you to have 12 volts to coil at all times. If all this checks out try another ballast--it should get hot if it is working. Also if you find the resistor wire check it for voltage with switch on--should be about 8 volts.
www.geocities.com/jhow66/2-.html

[Longhorn Man]

Originally posted by jhow66 If yellow wire is live with switch on your soleniod is bad. This will cause you to have 12 volts to coil at all times

Hmmm, you might be onto something there...if the yellow wire is attached to the large post on the starter, or rubbed and touching the post, that would cause it too.

[Twilightoptics]

Okay I do have 9 volts when in start position. 12 volts in on position.

Points were way to far apart. Got the truck to hickup, then no spark again. The cap is very loose, and the whole plate that the points are on moves. Looking to just toss this point thing and go HEI..

Where say online to I get me just an generic HEI dist for cheap? Not like cheap crap but I am on a tight budget. Junk yards around here never know their inventory so I'd be on a wild goose chase not knowing EXACTLY what I'm looking for. Thankie! :O)

[jhow66]

Did you disconnect the wire on "R" post when you checked the voltage at the post. On the HEI just about any Chevy V8 big or small block will work--just be sure advance weights are not wore out. The voltage check you made should be the other way --12 volts at start--9 volts at run or on.

[Twilightoptics]

Okay so far I've established I fried the points because I have too much voltage.

Put a ballast resistor on... and I still have 12 volts at on. I will check the yellow starter wire in the morning.

How hard is it to convert to HEI anyhow? I may just get the voltage down, buy some new points..... and sit till I have enough $$ for HEI.

[O'l Buck]

i think i can answer this question with 3 letters..... H E I .....it's worth the extra money

[bobs409]

Only real men run points. LOL

I guess im from the old school but I like points. (I know HEI is better for many reasons though) If you go with HEI, take my advice and carry an extra ignition module and tools to install. When they go, they don't care where you are at the time.

If you do that, you'll be happy with the HEI. But there's nothing wrong with a properly tuned point system either. (had to get that in there)

[CE20934]

Hear hear! I run points on both my trucks. Well, one truck and one bus. Prevents overrevving (4000-4500 RPM = point bounce = truck goes no faster). What other ignition system gives you a nice shock while you're trying to adjust it?

Plus, when the aliens come and zap all electronics, my trucks will still run! And all who follow the fallacy of HEI will weap. (maniacal laugh here)

Fire extinguisher fumes do odd things to a person's brain.

[Twilightoptics]

K so I replaced the cap/rotor/points. Poof running truck. Now if I can just get the carb to pump a descent amount of gas. D*** quadjets.

Thanks guys! Helped a bunch.

So did the local auto electric shop. Says I get 12 volts when points open, and lower when points closed. Which I have. Sweeeeet.

[roger0080]

Right on Bobs409 about points!

Quadrajets are great also. You just need to get it back into *proper* working order after all these years of previous owners that God only knows did what to the truck.

-Roger

[imdarren]

Twilightoptics,
I live out in washougal. Drive out here a get this HEI distributer I have laying around and install it. You can have it for free. Then you can rid yourself of points, coils, and all that stuff.
You don't have to. But it's yours if you want it.
Darren

Oh, yah. Get that voltage down where it should be, and your problems will most likely go away.

[bobs409]

HEI's have coils too.