Sparkless after neg ground conversion

[Go_Dogs_Go]

I installed an alternator. I followed the advice here to connect B+, A and A1 lines on (Lucas) alternator including the blue striped wire (BTW I have 2 of them). Brown and brown yellow together (to indicator light) and discarded the F wire. Black went to ground. The regulator is gone. Car is a 66 sprite with a 1275 engine from a few years later.

Removed the Pertonix electronic distributor because it was pos ground. Installed the old distributor (car ran with that originally). Static timed the car and checked that points open and close.

Rewired the aftermarket fuel pump.
I have no spark from the coil. Thinking that I somehow ruined the coil, I replaced it. No spark. I have juice between the coil terminals with ignition on. I have power to the alternator. The car turns over. No spark. No spark at any spark plugs.

Plugged a test light into the lead from the distributor to ground. No flashing while cranking or while manually turning crankshaft. Unplugged the hi tension lead to the distributor and had an unsuspecting soul hold it in his mouth while turning on car - no pain/no deaths.

I cannot figure this out! If you have anything to offer I will try and get back.

At this time I suspect points and condenser because I am grasping at straws. What could cause no spark to the plugs or the hi-tension lead from the coil in this situation?

 

[Sarastro]

When you attach a test lamp to the supply side of the coil, it should be on continuously (with the ignition switch on, of course). If you attach it to the distributor side, it should flash as the engine cranks. If it's continuously off, the points are either not opening, or you made the classic mistake of hooking up the condenser incorrectly so it's shorting them out. That spring thingy on the points should make contact to the condenser wire but not to ground; there is a (usually) nylon piece that insulates it. Or, it could be that the condenser is shorted, but that's not a common failure mode.

 

[Go_Dogs_Go]

Steve, thank you. When you say "attach it to distributor side" what do you mean?
I take that to mean that if I take a test lamp and connect to the negative side of the coil but do what with the other end of the test lamp?

I completely rebuilt the car in 8 weeks (braking system, suspension, interior, paint, etc) but electricity is NOT my forte. Thank gosh it was running when I bought it.

Thank you with your help. I also wonder if you can answer for me the question of what it means to "connect a test lamp in parallel with the points"? I found that in the Haynes manual and also another book. I am admittiably stupid with electricity. I appreciate your help.

Never work on a British car on independence day. I placed a british flag on the car today, bit it did not help.

 

[nomad]

The positive side of your coil is hooked to switched hot the negative side of the coil is hooked to the points( distributor) lead. By doing what Steve suggested you are checking the points in parallel. The points take your lead from the coil to ground when closed. When they break a spark is produced in the High tension lead which goes to the distrbutor cap for 'distribution' to the plugs. Should be intermitten flashing of test light as the engine is turned over.

Kurt.

 

[Bayless]

Steve is our electrical guru but I will try to answer in case he doesn't get back soon.

By "supply side" he means the coil terminal where the white wire from the switch attaches. By "distributor side" he means the other connector where the white/black wire that goes to the distributor connects. The other end of your test lamp always goes to a good chassis ground. To "connect a test lamp in parallel with the points" means to connect one of the leads to either the distributor side of the coil (see above) or to the distributor where the white/black wire connects and the other lead again to a good chassis ground.

Also, when you reverse the polarity from positive to negative ground, you should reverse the leads to the coil. The white wire from the switch should connect to the + side of the coil which may be labeled CB (for contact breaker). The white/black wire to the distributor should connect to the - side of the coil which may be labeled SW (for switch). Note that this is opposite from what how it was wired originally.

Steve's suggestion is certainly the place to start. Most likely your points are not opening or you have the spring or some other part touching the distributor case or breaker plate. The test with the light in parallel will answer this quickly. Let us know what you find.

 

[BlueMax]

Just wanted to add to this thread in what I’ve read. Your coil, is it a Lucas coil? Lot’s of guys will throw a different coil to the car after they change to electronic ignition. The Lucas coil has an internal resister. If you are using anything other than a Lucas coil you need to see if it has an internal resister. If you’re not, operating your ignition system with out a resister coil what will take place is this. The points will heat up and melt the cam lobe causing the points to close making your points unable to open and close to release the high tension voltage from your coil. All Lucas ignitions systems that are utilizing points must have a resister in the system. Might want to check that?

 

[Go_Dogs_Go]

The car would not run with the ground wire connected to the coil. That is why I had no spark. In connecting everything back up and testing the points as suggested with the test light, I left off the ground wire by mistake and the car started up. I think it was left over from the pertronix electronic module and I mistakenly left it connected to the coil. The coil has an internal resistor - thanks for that tip.

Thank you for your help in solving this.

 

[JeffS]

The ground wire added for the positive ground Pertronix was basically tricking your distirbutor into thinking the points were always closed. The points replicate what the ground wire was doing - collapsing the coil.

My first recommendation for anyone trying to get a car running with no spark is to disconnect all but the essential wires form the coil - power in and the switching wire to the distributor. Many time like this an extra wire, or a wire from a faulty tachometer will cause a car not to run.

 

[regularman]

You would think there would still be a way to use that Pertronix even with the conversion. You would just have to think it through.

 

[Go_Dogs_Go]

Thanks Jeff. Yes I learned that tip from this exercise.

I moved the answer on converting the Pertronix to my posted question regarding converting Pertronix to negative ground.