Wiring question. No spark, need help.

[RyanBez]

Alright, so since I have positive ground on my car, I'm a little confused about the coil. I got the Lucas Sports coil (Moss #143-200) and it has a + and - for the non-distributor side of the coil. Do I connect the terminals like it implies + to +(GND), or is it switched?

 

[Deleted member 8987]

Re: Dumb coil question.

I cannot specifically address that Lucas coil, but, from long experience, if positively gounded, the "+" goes to ground, or points, which is "+".
The "+" and "-" marks follow tha battery. The problem is when it's marked power and distributor.

 

[RyanBez]

Re: Dumb coil question.

Alright, so I'm trying to just start the engine for the first time and have rigged up some wiring. I know I am not getting a spark and just want to make sure everything is wired correctly.

The starter seems to turn the same way no matter how you connect it, +/- wise, which is curious to me. Regardless, the starter is turning fine. To keep with a positive ground, I have the base of the starter connected to ground (+), and the lead of the starter connects to - (with a switch inbetween the lead and the battery).

This is where my ignorance about distributors comes in place. I get the concept of how they work, just not totally sure what I'm doing wrong with the wiring. I have a wire from Negative to the + of the coil, which I take as the primary coil (standard for transformers). The - of the coil goes to the terminal of the distributor (Moss #153-640). I've tried switching this to no avail. I also have a wire from the base of the distributor to Ground (+). Obviously the secondary coil is connected to the distributor cap.

The distributor rotor is spinning the correct way, I've checked the points gap and they are correct and seem to be working fine. Why am I not getting spark?

The fuel pump is connected standard with + to + and - to -, and it is working fine. This is all I have connected since it is the bare minimum needed to get the engine running.

Since I don't have the car connected to the generator, I've tried wiring it with a Negative ground, this obviously didn't do it otherwise I wouldn't be asking for help.

 

[Sarastro]

Re: Dumb coil question.

At this point, I think you need a test lamp. Connect it to the distributor side of the coil and see if it flashes when you crank. My guess is that the points are not really opening or closing, or that they're somehow shorted out. Check the connections to the points inside the distributor; people often get that wrong.

Oh, as for the starter--it will indeed turn in the right direction, regardless of polarity. When you change the polarity, you reverse the voltage at both the armature and the field coils. If you reversed the polarity at only one of those, it would turn in the opposite direction, but since both are reversed, it turns the same way.

 

[Deleted member 8987]

Re: Dumb coil question.

Did you mess with the points at all from the time it ran last until now? Got the wire and spring on the points all on the correct side of the insulator?

 

[RyanBez]

Re: Dumb coil question.

First, the engine has never ran, this is my first attempt after a rebuild (from the last owner) but was never started. I have looked through the engine and everything looks sound (I can hand crank the engine fine). Regardless, I should still be able to get a spark at the plug.

So I took the distributor and coil out of the car and set them up at my workbench. I tested the coil and it worked fine (as it should since it is brand new). You are correct about the insulator. Like a rookie, I put the wires on top of the insulator so it was therefore grounded. After switching this, I hooked up my DMM to the coil leads and hand cranked the distributor. Sure enough, the DMM dropped from 12 to 0 when the points opened.

However, when I put everything back in the car, I am still not getting a spark at the plugs. One thing I did notice, which I'm not sure about, is that the points would arc when I hand cranked them. This should be ok since the arc stopped when the points where at max distance (and the voltaged dropped), I thought it was worthy to note though.

Any other ideas?

 

[Deleted member 8987]

Re: Dumb coil question.

Bad condensor (I've had them go bad and KILL the spark RIGHT NOW). Rotor.
Last thing you want to check is spark at the plugs. First place is the end of the coil wire. If you have it there, and not at the plugs, rotor, cap, or wires bad.
Arcing can be normal, depending on how dirty/worn the points are, but can also indicate a bad condensor, or one not connected to the same place as the spring and wires on the points.

 

[RyanBez]

Re: Dumb coil question.

TOC, I bought a new condenser from Moss, but I'll try to replace it with the old one and see if that helps anything. I essentially ran the same test that Moss recommends for testing coils and the coil worked fine:

https://www.youtube.com/watch?v=rJYJ3KvPhhY&feature=player_embedded

So I guess the issue could be the condenser or possibly the cap. The rotor, points, condenser, wire (bumblebee), and coil are all new. I took out the old cloth grounding wires and replaced them with some 18 gauge wire.

Problem is, I have this week off, but not next so it would suck if I had to order parts. I took the week of to get the thing running and do some painting (which can't happen from this darn heat wave). So this whole week could turn into a bust! Oh well, at least I got to sleep in for once.

 

[Bayless]

Re: Dumb coil question.

If I understood right what you said earlier, your coil is connected backwards. The side of the coil marked - should go to the - side of the battery and the + to +. So the + side goes to the dist and the - side to the switch. As TOC said earlier, the confusion comes in when the coil is marked power and dist or as mine is, sw (for switch) and dist. This should not cause your no spark problem though although it could make it a little weaker and cause excessive plug wear.

 

[Deleted member 8987]

Re: Dumb coil question.

There was a test we used to do....running of course....for coil polarity.
Hold a plug wire near the block or head, hold a lead pencil in the spark arc......if the polarity was right, I think it was the glow went towards the block/head.

 

[RyanBez]

Re: Dumb coil question.

After testing things again and no luck I broke down and ordered a flamethrower. I got the negative ground one so I can work on the conversion while I'm at it. If this doesn't fix my issues then nothing will!

Once I get the car running (and painted), I'll look into the original distributor. I hate leaving things unsolved but I don't have time to waste on this right now, too many other things to do!

 

[Bayless]

Re: Dumb coil question.

As I recall, you're right TOC. But I never can remember stuff like that with certainty. Anyway, as long as the coil is marked + and - then it is plain simple. Put + to bat + and - to bat - and all is well.

 

[RyanBez]

Re: Dumb coil question.

Bayless, I don't think you connect it that way. The way the coil works is that it is normally grounded with the points closed. However, when the points open, the coil looses it ground and 'finds' one using the rotor to hit one of the spark plug wires. If you just connected each side of the coil to the battery it would never loose a ground and never give a spark.

The Haynes manual has a nice drawing of how it should be connected, but it fails to mention whether it is for a positive or negative ground. It also uses the dis, sw markings, not +/-. Also, because the coil is a transformer, you would want the + to the primary (+), but I've never worked with a positive ground circuit before so I'm not sure how that changes the properties of the circuit and how to wire the coil.

From the wiring I have it 'should' be working fine. However, I fear it is grounding somewhere other than the spark plug wire. This could be an issue with the cap or any number of things, which is why I broke down and bought the flamethrower. I don't want to keep buying a new 25D part by part trying to resolve the issue

 

[Deleted member 8987]

Re: Dumb coil question.

Positive or negaitive makes absolutley no difference. A coil will work either way, just usually at higher revs, will misfire if backwards.
It doesn't matter for testing purposes.
If the points make the test light blink on the dist. side of the coil primary, you have two choices. Bad or mis-connected condensor (the condensor is needed in the circuit for spark arc control at the points and for development of the spark in the primary) or bad coil.
When the points open, the current through the coil is disrupted, and the field collapses. The collapsing field tries to maintain the current through the coil. Without the Condenser, the voltage will rise to a very high value at the points, and arcing will occur.
The principles of inductance create a kind of paradox, because when the points open and the magnetic field collapses it also induces a current in the primary as well. It's not very much because there are only a few windings in the primary, but it's enough to jump a small air-gap, such as the one between the just-opening points in the distributor. That tiny spark is enough to erode metal away from the points and you'll 'burn' the points. It prevents the points from arcing and prevents coil insulation breakdown by limiting the rate of voltage rise at the points.

Test one: Pull the coil wire out of the centre of the dist. cap, see if you have spark there.
Next, if you have an ohmmeter, check the resistance of primary and secondary.
Three, check or replace the condensor.
Four, replace the coil.

You can jump to four, the most expensive item, and find that isn't it.

I've been doing this for a lot of decades......you get to the point you just do the proper sequence of troubleshooting, and you find it.

Is the condensor wire on the same side of the insulator as the point spring and wire?

Reason I ask is didn't you mention seeing sparking at the points? Unless very dirty of corroded, you generally won't see much there.

 

[RyanBez]

Re: Dumb coil question.

TOC,

The condenser is connected on the insulated side of the point spring. The condenser is brand new, but it could be bad.

I've tested the coil and it is arcing correctly. Like I said before, I think the rotor may be grounding to the distributor base or something else and not the spark plug wires. The distributor cap is original and in bad shape, I cleaned it up the best I could but you can only do so much.

I guess if the flamethrower doesn't fix it then I'll know it is the coil.

 

[Deleted member 8987]

Re: Dumb coil question.

If the coil is sparking out of the coil wire to the head, it isn't the coil, or points, or condensor.
Rotors are a BIG problem, especially if you got one of them good Lucas ones, but usually the rivet breaks the plastic out.
Rotors do carbonize on the inside, and can short the spark right into the dist. shaft. The carbon button can be missing in the cap. The cap can be cracked/carbon tracked to the point current goes down the side to the dist. case.
How far an arc does the coil put out?

 

[RyanBez]

Re: Dumb coil question.

The coil puts out a decent length arc, it is the Lucas Sports Coil (40kV). The rotor is brand new and is the premium rotor that Moss sells. Because I can't see inside the distributor when it is going, I don't know for sure if it is the points arcing, or the rotor grounding to something else...

I do believe a new dis. cap and maybe a new condenser could do the trick, but I didn't want to risk it since I'm on a short time frame. I want to make sure the engine is mechanically sound before I start the engine bay painting!.