No spark....but there was!

I had a spark from my Lucas RS1 but everything  looked tired and grubby and it was all a bit, shall I say, intermittent!

Therefore, as this is a major overhaul and restoration, I decided to replaced points, condenser, HT lead and plug - all acquired from Stationary Engine Parts.  There is no resistance at all from the brass connector in the 'lid' of the hovis tin (if you get my meaning) to the brass connector to the spark plug.  I've used my feeler gauge to correctly set the gap for points and plug.

Now - you've guessed correctly - no spark.

I'm a little puzzled - maybe I should strip down, clean up and put everything back together?

Any thoughts please?

Many thanks.

Chances are you have reassembled the points, insolasion spacers and wires incorrectly and its now a dead short to earth. Without taking a magneto apart I cant tell you the order but it should be obvious.

Maryalice

maryalice wrote:Chances are you have reassembled the points, insolasion spacers and wires incorrectly and its now a dead short to earth. Without taking a magneto apart I cant tell you the order but it should be obvious.

Maryalice

Thank you. I did wonder if it was, in effect, tracking to earth somehow. That being said I did reassemble carefully - but then again maybe not!

Hello, I have returned to ask for more help please with the above problem. I cannot find a really clear diagram for correct reassembly of points with all the attached bits and bobs. I have the Lucas magneto manual which is downloadable but the bit I need is simply not clear.

I am quite confident that Maryalice is right about it earthing because before I replaced condenser and points it did generate a spark although sometimes across the points before the new HT lead and plug were fitted. This latter points leads me to believe the coil itself is 'active'. This is a steep learning curve for me and I am grateful for all advice.

Thank you.

Spark doesn't mean the coil is good, I've got at least 2 mags outside that spark but the windings are open circuit, they won't start an engine as they are not strong enough to spark under compression.
Stick a multimeter on 20kohms and measure the resistance from the HT lead to the case of the magneto.

From the HT lead (and also from the brass nipple on top of the coil) there appears to be maximum resistance to the magneto casing. I've assumed the MM leads should be on the outside of the casing and the end of the HT lead.

I've also noticed on both of the mags I have, one with new points and condenser and one not, that there is continuity (i.e. no resistance) between the spring tail and the retaining pillar. I think this is not correct.

Now chasing my tail! Sorry if I am being dim.

From the brass nipple on the coil to the magneto body there should be about 5-7k ohms for an RS1, sounds like the coil is open circuit.
When I measure I put my positive probe on the ht lead terminal and the other on a cylinder head stud. If that doesn't work I move the negative to the magneto body. If that doesn't work I move the positive to the coil nipple. No ready their I take the coil out, then give up on the coil....

It seems likely that the coil needs rewinding. Anybody done this themselves or which companies have you used please?

I've used: https://www.facebook.com/vintageworkscheshire/
And Martyn and Andrew Dry in Bristol (evenings) 0117 9675225 I think they are still going.

Good evening everybody. May I say, first of all, thank you for your patience and support with this 'newbie'. I thought I was tech and engineering savvy then I acquired my Lister D!

As yet I have had little time to further explore the issues with my Lucas SR1 fitted to my Lister. However, I had a thought when I had five minutes this afternoon. If, when the points are open there is an open circuit - that is to say, as I understand an open circuit, there is continuity across both parts of the points - there's a problem with the way I have fitted the new points.

There is an open circuit - when I put the continuity across both sides of the open points the multimeter shows there is no resistance. So - and sorry for being long winded - is my logic about the open circuit correct? If so, I clearly have a problem. As the French say, 'N'est pas?'