Mystery Bamford engine

Where would the condenser be? there is not one on the points plate where I would expect to see one, I have not completely stripped it down. I am on a big learning curve here. Thanks for everything, I will have another look tomorrow. Regards Pat

The capacitor is embedded within the armature. Unfortunately it can only be accessed by a complete strip-down of the magneto.

Edited By Swarf Maker on 26/06/2019 01:00:14

Yet another point, for longevity of a magneto, is to avoid generating into an open circuit - or even a too big spark gap. The voltages and energy have to be dissipated within the magneto coil which is not as robust as a normal, more modern, external coil such as used in the Kettering ignition system. Both points opening and spark plug gap are usually a few thousandths (5?) of an inch (~0.1mm) less than those utilised in a Kettering ignition system.

The condenser may be stressed or the coil insulation can break down.

Most magnetos can be reversed (perhaps not the earliest models). The contact breaker cam needs to be set in a suitable alternative position - to align the generation side with the points opening timing. Also, if the magneto has an impulse coupling, which winds up a spring before tripping and spinning the magneto at higher speed (only operational at cranking speeds), would need to be reversed, if set for the wrong direction of rotation.

The early magneto's can be reversed but it usually means new mechanical parts including the impulse couplings, changing the direction of a magneto without parts is possible but its not easy and can be hit and miss trying to find the sweet spot. A single cylinder magneto would make life easier to set up and things like the capacitor are usually mounted in the magneto cap and not the windings.

If you can wait until November there is a big bring and buy sale held here where you may find another magneto and parts for the engine.

Martin P

Saturday 2nd November

Cotswold Oil Engine and Preservation Society

Bring and Buy Sales

Oakley Airfield, Worminghall, Bucks HP18 9PH

For the WICO style of rotating magnet magneto Martin Perman is correct in that the capacitor (condenser) is mounted in an easily accessible position. The magneto currently in place on this engine would appear to be a rotating coil magneto and with those it is common practice (but not universal) to embed the capacitor in the armature.

Wico,Lucas, ML single cylinder mags all have accessible capacitors

Martin P

Thanks for all the replies. I have got the armature out and still can't see an obvious capacitor, I have taken photo's and the first one shows a small brown cylindrical object with a wire from the winding going into it, if it is I can't see how to remove it. Help! Regards Pat

Regards

Following on I have just found the Brightspark page which shows how to do the job chapter and verse, I will try to digest it and report back on the results. Thank you all for your help and I do feel that I have taken up a disproportionate amount of your good nature. Best regards Pat

Pat,

Just PM'd you with my Mag repairer details, ring him after 18:00 though.

Martin P

Likely as cheap to buy another (but always the risk of a dud). There will be lots on sale at the end of July, at the Cheffin’s vintage sale at Ely. Not the cheapest place to buy one, mind, depending on demand.

Pat, as you will have now seen, the capacitor (condenser) is contained within the brass body at the contact breaker end of the armature. The centre screw that I said yesterday should not be insulated, actually screws into the body of the condenser. As a consequence you need to retain some of its physical presence - if not its electrical connections. The Brightspark tutorial is good but you need to be very careful removing the slip ring when dismantling the armature. The HT wire from the armature coil usually becomes corroded where it enters the slip ring so clean it well when putting things back together. The wire is just a push fit into the hole and establishing a good contact is a bit hit and miss.

I will probably fit the later type of condenser either a CO1 or CO2 which fit on the points plate depending on the rotation which I need to work out. The internals came apart fairly easily and it has been a very interesting journey. Thank you so much for all of your help. Best regards Pat

Pat, looking at your photos you are going to have to dismantle the armature in order to disconnect the old capacitor (condenser). If that is not done it is likely to be a pointless exercise in mounting a 'Brightspark' capacitor at the points plate. You need to follow the 'complete works' chapter on the Brightspark website in order to repair the magneto that you are working on. Any defects in the old capacitor, other than a complete open circuit, will continue to influence the working of the magneto. Even if the capacitor is currently open circuit, it may well re-establish a connection and hence a fault condition, when in service.

I hope that you followed the advice to provide magnetic 'keepers' for the magneto body before removing the armature.

I have removed the capacitor so that I could match it up but I have now decided to get the CO1 from Brightspark which seems to be the best way forward. The magnet is firmly clamped on my metal top bench and I have cleaned everything ready for assembly. Thanks all for your help and I will post the results of my labours good or bad in a few weeks. Regards Pat