Intermittent power loss 1975 rb roadster

[Charles Farran]

Thanks Vic, as i think we have discovered before the harness diagrams & dates of intro are not always accurate & vary depending on markets the cars were going to at the time!
Cheers, Charles

[Paul Scott]

Well I had a quick peak during my lunch break.

Does the earth wire from the condenser to the distributor body have to be covered? It has a cloth covering on it but this was pulled back allowing the inner to touch the outer casing of the condenser. Guessing this doesn't matter as the condenser body is screwed to the plate along with the wire.

Sucking on the auto advance the plate moved a tiny bit then returned, swapping the angled end to the straight end made the plate move further and stayed in place until i removed pipe from my lips. Could this be causing the backfire but not the dying I'm getting. I plan to change the pipe and connectors for a one piece rubber hose due to the ends being troublesome in my case. Any issues with doing this?

Terminals are tight onto the coil, but did not get time to stick my meter on for continuity or voltage measurement.

White Black wire on the coil - I'm guessing from the wiring diagram one goes to condenser - other to the tacho.

2 white and green wires are actually connected via one lucar terminal. one of which go to the Starter Motor - the other to the ballast resistor then changes to white at the fuse box I believe. I will find out more when I have a little more time with my meter to check this out.

If I locate the ballast wire could I change the wire and add a seperate Ballast resistor near the coil?
Any Ideas on an approximate resistance for the Ballast wire that is currently fitted?
Which reistor could I use Or should I replace the coil for a 12v type? would this make my points wear faster?

Thanks in Advance for sharing your knowledge ;0)

Regards
Paul

[Vic Butler]

Provided the condenser wire hasn't lost its insulation and isn't shoring then there shouldn't be a problem.
On the negative terminal of the coil the black wire goes to the distributor and the other to the tacho.
If the resistive wire is faulty then get a 12v coil and run a wire from the fuse box straight to the plus terminal.
One more thing that can cause problems is the cheap black rotor arms that barely last 5 minutes although that wouldn't affect the LT circuit. The Distributor Doctor sells red ones which are far superior and if you need points, condenser or distributor cap that is the place to go.

[Paul Scott]

Thanks for that Vic

Condenser is newish - DD red rotor arm already on.

I am going to change the Auto advance hose as I am sure that is not working. I have ordered a new ballast resistor today going to add a fresh lead to that. Cutting out the old one to see if that s the issue. Then I may have to get a new 12v coil if problem persists.

I have located the joins for the ballast cabling within the loom. I am confident I can seperate the feeds to make that wire powerless.

I might even get it sorted midweek & give it a go.

Thanks again for the knowledge

Regards
Paul

I'm going to look at a 80's GT tonight that a friend cannot get to fire. But looking for my own fault might have assisted me with this problem as well.

[Vic Butler]

Paul, that car will have a an ignition relay and a starter relay. When the ignition relay failed on mine a couple of years ago, the engine would fire but as soon as the starter was released it died.
A faulty vacuum advance won't cause the engine to cut out.

[Charles Farran]

Not sure why you think there is a problem with the ballast resister feed. When the enngine cranks it uses the unbalasted feed from the solenoid on the back of the starter motor to give 12v to the ballasted coil,as soon as the engine fires then the LT supply reverts to the ballast resister feed so ongoing supply at 6v to the coil (which if not altered by a PO ) should be described as a ballasted coil.If you use an unbalasted coil on a ballasted system you will get a weak HT spark. If you use a ballasted coil on an unbalasted system then you will probably cause the coil to breakdown as it gets hot.The dual wire system you have is designed to give a better spark on starting to make the process easier!
Cheers, Charles

[Andrew Vigor]

Hi Paul, it's worth checking that the wire from the condenser to the body of the distributor isn't fractured. The advance mechanism can cause fatigue and an intermittent connection. I had this happen once. It's worth checking all the wires inside the distributor.

[Paul Scott]

Hi Charles,
I'm trying to rule out the ballasted feed being the issue by renewing the cable from the connevtion point to the coil adding a ballast resistor into that feed. It could be a faulty coil, but the issue is intermittent like a break in power to the coil as the tacho dies engine cuts completley then comes back to life.
A similar thing happened earlier in the year after I moved the cables under the bonnet. But after changing all of the lucas 2 & 4 way connectors we have not had an issue.

Its just like turning off the key for a few seconds then back on again. When it did it in april indicators & brake lights stopped to. Don't think this happened yesterday.

Regards
Paul

[Paul Scott]

Hi Andrew,
I have the earth lead out of the distributor currently. It is intact although the ring connector has been replaced with a red crimp on effort. I don't use this type as a rule because I dont feel they make a good connection. I have the tools to change the connector properly so that will be done.

I was looking at my friends 80 B GT tonight & the earth lead was fitted differently. Condenser to the nearest dizzy bod screw. Where as mine was stretched over the condenser. Unsure which is correct but the shorter route looked better.

Regards
Paul

[Vic Butler]

Paul, before you fit another ballast resistor check with the ignition switched on that there is power to the coil from the relevant white/light green lead and wiggle it about to see if there is an intermittent fault.
The distributor on your car should have the number 41610 as should the LE.
The tag on your carburettors should show FZX 1001.