Spark goes in but does not come out

 Absolutley crap with electric issues, my friend is asking me to help him out getting his 1975 Triumph TR6 running again. 

Story goes he was out running errands in his TR6, pulled in to the parking lot and car stopped. Could not get it started, another friend came along found the wire from the distributor body to the breaker plate was fried. Put a new wire in and did not fix issue. Started loading the busckshot in. and the following got changed out.

New pertonix pick up, replaced, no joy, new negative battery cable put in from negative pole of battery to Engine where the braided ground goes to body. Continuity checked from  engine and body, good to go.  Still no spark coming out of distributor to spark plug. Replaced distributor cap, rotor, coil, and battery. Still no luck. Now I have been enlisted to help.

Checked continuity between distributor casing to battery negative was good, continuity between the distributor body and plate the points would mount to, also followed the advice of the pertronix tech and checked from the plate the points mount on if it did not have pertonix to battery and was good. Took a light that goes in between the spark plug and wire. Checked spark was coming out of Coil, Hooked light up to wire coming from coil and going to distributor cap found spark going into distributor. Checked with light from distributor cap to spark plug wit\re for #1 & 4 no spark coming out.  

when ignition switch is turned to run have 12 volts at positive terminal of coil, while cranking voltage drops to 8 volts.

Looked through Triumph forums and found a couple of threads where they had a similar issue of spark coming from the coil going into the Distributor cap, but not coming out from the distributor cap to the spark plug wire. Unfortuantely no happy ending with the OP not coming back and letting everyone know what is was that fixed the issue.

Any help is appreciated.

I'd put points back in to rule out the Pertronix. With old school points, it's easy to see if they are firing. 

With the distributor cap removed...Hold the king wire from the coil just above the metal strip on the rotor while cranking the engine over. If you see a spark jump, you have a leak to ground from the rotor to the distributor shaft.

Bad rotors were legendary about 10 years ago.

Also check the spring loaded button in the cap to make sure it is contacting the rotor surface. The button has been known to go missing

Is the rotor turning?  Meaning is the distri utor shaft actually rotating with the engine cranking?

That breaker plate wire being fried is where I'd be looking - that is definitely wrong and if properly replacing it didn't fix it, whatever caused it to fail probably would 

In reply to NOHOME :

Thank you for the response, there is a witness mark from the distributor button in the cap on the two rotors that my friend had. Will check the king wire to the rotor while cranking and look for a spark. Did take a continuity test from the little metal tension tab on the rotor to the copper strip on the rotor and found it open.

In reply to jfryjfry :

thank you for your answer, agree with you that the wire fried probably would give me the current underlying issue. Unfortunately I did not start the troubleshooting process. this was started by my friend and another mutual friend. they said they did find an issue with battery cable to ground. It now has a new ground wire as well as another cable from engine to body. wether this was the issue for the one wire to burn up I am not sure.

Did find the replacement wire a little loose at the breaker plate there was a crimp connection and it was also soldered. This was crimped tight, and then got a better solder iron and ensured it was a tight joint.

In reply to wvumtnbkr :

yes rotor turns when engine is cranked over, also verified that rotor was not out of phase. Put engine at tdc #1 Rotor was at the approximate location of the #1 sparkplug lead under the distributor cap. Spun the motor over and rotated distributor to verify if we could get any spark coming out of the cap and ensure we were not totally out of phase.

I've found the spark testers with the lights can give a false positive.  Just use a spark plug or position the wire so that it arcs to ground.  If you're really getting a spark from the coil wire but not one of the plug wires then you've got a defective cap, rotor or the rotor is out of phase.

The 8v at the coil while cranking is a little low and could be an issue although I doubt it.  If the battery voltage is dropping that much while cranking try cranking with a charger on the battery.

If you put a 12v test light on the distributor side of the coil it should flash while you're cranking.  If it doesn't then you've got a problem with the Pertronix unit or the wiring to it.

In reply to APEowner :

Thanks, The battery was 4+ years old, he bought a new one and a starter relay which he will install this week. Like the tip on how to troubleshoot the pertronix unit just to take that out of the equation.

Had an MG TD that did this.  It was a bad carbon button in the distributor cap. Resistance had gone through the roof.  No idea why.  No obvious signs of arcing or carbon tracks inside the distributor or cap.  Replaced the cap, and the sparking now went down to the spark plugs.

In your list of parts replaced I didn't see the condenser.  Have you checked that?  Maybe it's shorting out internally.

NVM.  I just realized that the Pertronix eliminates the condenser too.  Another thing to check is whether the coil is internally ballasted (e.g. Lucas Sport coil).   If it is, it needs 12 volts and the wiring harness ballast resistor should be bypassed.

So as a closeout to this thread, thanks for all that responded with thoughtful insight and advice and here is how the TR6 came to run again as told to me by my friend the owner of the car and another friend that was initially helping him.

Distributor caps from Moss Motors did not work, got one from Rimmer Bros and it started firing. took the distributor cap off and the button fell out. little crazy glue and it has been running since! They also put a jumper from the top forward lead at the fuse box on drivers side of car that is 12V switched to the coil terminal.

My Mates coming over from the UK in a couple of weeks to visit me here in Florida and to do a SCCA track night at Sebring with me. So will order a couple of caps if I can find some by known English manufacturers that I would have confidence in and have my friend bring them over to me. Then bring them up to my friend in North Carolina when I go back up to Virginia to work next month.

Kind of a roundabout way to get a cap and rotor but might be the best choice due to the uncertainty of the quality of parts sold over here!