28 replies to this topic

[steerling]

Fantastic, plenty of information for me to get troubleshooting tomorrow morning. I'll report back with my findings!

[KernowCooper]

Just to add while your testing, the distributor is lubricated by removing the rotor arm and there was when made a felt pad in the centre, most of these are now missing, drop 2 drops of engine oil onto the screw head, this will find it way down the shaft and lubricate the bushing of the advance retard mechanism, if your hearing a rattling noise suspect the advance weights, remove the base plate and check. Don't fall into the trap of thinking one spring worn they are primary and secondary springs and of a different value.

[dklawson]

they are primary and secondary springs and of a different value.

 

And the springs may appear loose also.  Being loose does not necessarily indicate a problem either.

 

If you do not have the felt wick that rubs against the 4-lobe cam below the rotor, a thin smear of light grease on the cam is dictated.  Without some form of lubrication on that cam the heel block on the points will wear quickly causing the points to close up... and engine to not start.

[steerling]

Test one, take a plug lead and put it in the coil's HT connection, install a plug in the other end and lay the plug down near where it can arc to the engine, remove the CB- connection from the coil and run a temporary wire to it that will reach to engine block, switch on the ignition and dab the bare end of the wire to the engine to earth it, as you lift away the plug should spark, not when it is touching remember , hold it on then lift off and watch as you lift off for the spark.

 

Be careful near that HT lead and the plug etc it will bite!

 

I've managed to get a couple tests done today and here are the results. 

 

- Test one came up unsuccessful. I did not get any spark in that test. 

- Test two with the continuity i think is also a fail. I had the meter hooked up as described and i turned the engine over. I saw the points open and close but I the beep was my meter was continuous. I assume i was supposed to hear a break in continuity? 

- Test three proved that my coil had too much resistance. It was reading 5+ ohms. I purchased a new one today and that read 3 ohms so i've installed that but have not been able to rectify the lack of ignition. 

 

As you asked, the first thing i tried was the carbon/pencil trick. I'm afraid to say that it didn't work for me. I did also pick up a new rotor arm, point set and condenser from the store today. I installed the points and adjusted the gap to 15 thousandths and tried the new rotor arm after installing the new coil. Nothing seemed to work. I was not able to replace the condenser as it had a different connector on it which I did not realise until getting home. I will get the proper connection tomorrow and have that replaced too. 

[steerling]

I hope the condenser is the root of my problem and it is not a faulty wire in the LT circuit. There is lots of old/dodgy looking connections in my engine bay and the previous owner has done a poor job of wrapping everything in tape and generally making things difficult and messy

[sonikk4]

Well once the condenser is replaced you will know for sure as you will have replaced all of the ignition components.

[CityEPete]

Has the engine got a good clean sturdy earth? Until you are getting an earth on that CB wire as the points open and close you are going no where even though it sounds like the coil was either broken or just the wrong one so worth changing.

Edited by CityEPete, 01 June 2014 - 12:28 PM.

[CityEPete]

Next you need to confirm you have an earth on one side of the points and that the CB wire has a path from the spade terminal at the coil to the other side, do the tests with the wires disconnected at the coil. I'm now wondering if the dizzy base plate wants removing and cleaning?

[KernowCooper]

You have a small earth wire between baseplate and distributor body intact?

[CityEPete]

You have a small earth wire between baseplate and distributor body intact?

What he said^

[steerling]

 

You have a small earth wire between baseplate and distributor body intact?

What he said^

 

 

Yes there is a earth wire that was screwed down into the baseplate with the condenser and ran around the condenser and screwed in near the grommet where the -ve wire runs out of the distributor body to the coil ( as in the picture below which). There was a lack of washers on both the condenser and points screw. Are these entirely necessary? I will remove the base plate and give the the whole thing another good clean with contact spray before reassembling. I will check the integrity of the earth wire again.

 

How can i test whether I have established a solid ground? Do i run the continuity test again and expect to see breaks in continuity as the points operate?

[KernowCooper]

Washers under the screw does two things, the flat allows the points to be secured down without the rotation of the screw effecting the points gap while tightning, the spring washer just keeps the points screw tight, so worth having.

 

Do a voltage drop test on the small cable will show if its working, see the FAQs if your unsure on volt drop testing.

Edited by KernowCooper, 01 June 2014 - 09:24 PM.

[steerling]

Problem has been sorted!! 

 

I suspect it was simply a failed condenser. I don't know for certain because I did remove the distributor base plate and give everything a good clean, including the ground wire and connections, at the same time as replacing the condenser. Either way, I have sweet, sweet ignition!! Thanks for all the advice guys, it's been a good learning experience and now I know I have an ignition system full of new parts.

[CityEPete]

I suspect the faulty condenser was just shorting the points out then, now you know how it works life well be much easier in future, I made a mistake during the rewire of my mgb, it really annoyed me and took a day to sort out, that evening sat watching TV with a take away I felt glad it had happened as I'd learnt so much and it was all transferable to most British classics!