LUCAS GA4 MAGNETO

Well today has opened a bucket of crap with this magneto . With almost no magnetic pull in the magneto I thought at least when I get to it I can charge it up, more on this later. I took some covers off and actually got the things apart after removing the bush underneath, the end cover and the pick up behind that cover. Took off the arms and nut that hold the points box on and started to slid out the armature. I had a look at the points before removing and noticed they were not opening so I adjusted them to 0.015". Then took the points out and dressed them on my diamond file and put them back together.
At the time I removed the points box by undoing the small centre bolt it was then I knew my first mistake as this needs to be timed to the magnetic flux which I have not done before and do not know how to do it on this magneto. So I kept cleaning bits up and had forgot how to test the coil and the condensor in these things as the coil can be accessed but the condensor is inside the brass housing. So I need some help please in being advised how to test them and especially how to reset the timing of the points.
Next was the charging of the horseshoe magnet. I found N & S of the magnet and set them up in the opposite direction so that N faced S on the charger and visa versa.
I gave the charger about a 10 second boost and lightly tapped the magnet while doing so. Not much improved, so I did this a few more times and for a longer period and eventually I got some magnetism in the magnet. Is this normal?
Now I do have some slight resistance when turning the shaft around so maybe if I can set the points timing I might get some sparkles.

Cobba I will get some re-energising a magneto stuff shortly.

What do you mean by "set the points". As far as I am aware they are just like a car distributor with a cam to open to the feeler gauge measured gap and once the magneto is attached to the engine drive in the approximate right position it is fine-timed by moving the distributor cap. This is usually adjustable through the timing linkages fron the steering column lever ie your set up to the engine drive must be pretty close to the mark because the cap movement is limited.

Don't forget you can swap plug leads around to get close to the mark if you balls up the vernier or whatever drive attachment you have.

Lang

Lang on the Lucas magnetos and many other models by Lucas you have to set the points, not gap them, but set the timing of the points. The points are mounted on a plate and the plate is a taper fit onto the armature shaft. This means the the strongest magneto flux can only happen in one spot but I can rotate the points plate 360'. This means the points would open in the wrong spot. Then there is the timing of the rotor button which gets a mention in that great link from MG you kindly sent me but the magneto was stripped down and I was not aware this could be a problem as the instructions said to mark the gears before taking it apart. Maybe after a better clean up tomorrow I might find some marks from previous rebuilds.
I was hoping to get back to it today but will wait until tomorrow as I will have the weekend off to play with this and other toys.

I will try to find something. Just keep yourself busy trying out each of the 106 possible combinations of gear meshing!

Cobba This might help.




And This
www.gasenginemagazine.com/gas-engines/re...ing-magneto-magnets/

A bit puzzled about BTH GA4 and Lucas GA4

Despite my earlier assumptions it appears BTH were for many decades part of the General Electric/Westinghouse empire. I can not find confirmation of a Lucas cross-over. Here are the two GA4 magnetos. Both built at the same time for the same application. Both fitted to a wide variety of British vehicles, often the same model and British aircraft and marine engines.

Are they related or not? Top BTH bottom Lucas (disregard the input drive ends just for remote or mated installation offered by both companies)

I always thunk that BTH was British Thomson-Houston.

Morris you are correct. It is just the connection between the two companies that eludes me.

Reckon your right, Morris,
BTH or British Thompson Houston was a railway locomotive manufacturer of diesel-electrics, primarily used Paxman engines.
Think it was ansorbed into English-Electric, but IDSTBC
Dave_64

Talking magnetos . Thought some maybe interested in this one. It has been serviced and ready to go on the Richard Hornsby 6 h.p. 1911.
Now i just have to get the rest of the motor back together. Also chucked in a photo of carby.
By the way , for those not familiar with the magneto it is a "Flick" magneto and weighs 8 kgs. I do have 2 magnetos listed for sale on the Gumtree site.

General Electric was formed in 1895 by Charles Sprague who merged his Thompson Houston Corp with Consolidated Edison....Sprague was the first president of GE.......in GB in the 1920s there was a big fuss about US corporations buying key British companies ...using the money the Poms had spent on WWI in the USA.......Anyhoo,GE bought English Electric ,but the PM thought to hide the transaction by having a Pommy Lord pretend he had bought EE....when in fact he had sold it to the Yanks...............the last BTH mags Ive seen were fitted to British bikes in the 1950s...........the Qld Police Triumphs always had BTH mags in the pre unit era.......the BTH mag was always reckoned to be better than the Lucas K2F mag.....