Magneto Question

OK, so the new mag for the Stuart turned up today, I think the eBay seller might be having a little trouble telling the difference between clockwise & anticlockwise. He clearly said in the description that it had a good spark when rotated by hand, but didn't say in which direction, so I asked & he said "clockwise", you might be able to see it here....

http://www.ebay.co.uk/itm/321091453363?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1439.l2649

But, on receiving the mag this morning I discovered that not only is it an anticlockwise rotation mag, it also has an impulse. Now an impulse would be very handy for this engine, but an anticlock mag is pretty useless.

So, the question is; can I reverse rotation on this type of magneto?

The points cam appears to be symmetrical in profile, but I can't tell if the rotor has equally spaced magnets or not. I'm not really up on these later WIPAC mags.

Also, would be good to know if the impulse can be reversed?

Anyway, here's some pics of it....

yes it can be rotated. but it involves taking the innards from another mag the right direction. I was told that by a mag specialist.

matt

Cheers Matt. I've taken it apart now & can see that the impulse can be reversed, but the points cam is a machined part of the rotor & the magnets are not equally spaced, so I guess it would require a rotor from a clockwise mag.

Bit of a PITA, but I don't think I can be bothered posting it back to the seller, it only cost me £24 & there aren't that many of these models with base mounting (the vast majority are flange mounted). Maybe I'll find a use for it, if not I'm pretty sure the coil will fit in a Wico A, which means it should also fit in a Lucas SR1 & some (possibly all?) RS1 mags as well.

Now I just need a clockwise, base mounted mag for this engine, or a rotor out of a clockwise one of these types (think they're known as a WIPAC model CJ).

If changing the cam is impossible is it possible to remount the points to work on the other side of the cam? You just need to get the points to open with the rotor positioned in the same relationship to the body as in it's current rotation.

pjjms wrote:If changing the cam is impossible is it possible to remount the points to work on the other side of the cam? You just need to get the points to open with the rotor positioned in the same relationship to the body as in it's current rotation.

That could be an option, & TBH I hadn't thought of it. Might have to gave a little play with it when I'm feeling a bit better. I've still got to test the coil on this mag, as I've only seen it spark on impulse, & even a knackered coil can still spark on impulse.

Nuts can you please show some pics of you using the multi meter and what settings to use.

Thanks,

Stu.

yes coil is the same as other wico coils....easy eay to test at running speed is use a drill with a socket in the chuck and spin the mag....clamp mag down as well and clamp a spark plug to the mag body..

Nuts this has just finished on ebay but I saw it when it was to late. I know the seller if you want me to ask about it?

http://www.ebay.co.uk/itm/Wipac-Magneto-/310638282434?_trksid=p2047675.l2557&ssPageName=STRK%3AMEWAX%3AIT&nma=true&si=tiebLAXt8CYiPBf%252Bvlgtc78CPKI%253D&orig_cvip=true&rt=nc

Strange I just bought this one a few weeks back.

http://www.ebay.co.uk/itm/wipac-magneto-/140934725864?_trksid=p2047675.l2557&ssPageName=STRK%3AMEWNX%3AIT&nma=true&si=tiebLAXt8CYiPBf%252Bvlgtc78CPKI%253D&orig_cvip=true&rt=nc

Stu.

Could be worth asking him Stu. I've bought bits off him before & they've always been good. If it didn't sell I would definitely be interested.

Hi All

I have the same mag and having problems.

Where must the condenser be placed and what type will work.

Mine only sparks the plug when turning slow when impulse is working.
When impulse is not working when turning fast no spark on the plug.

Thanks Raymond.

Stingray wrote:Hi All

I have the same mag and having problems.

Where must the condenser be placed and what type will work.

Mine only sparks the plug when turning slow when impulse is working.
When impulse is not working when turning fast no spark on the plug.

Thanks Raymond.

It's probably the coil rather than anything else. I will take some pictures today or tomorrow & show you how to check it with a normal multimeter.

The condensers on these are a special type, but you could put any old condenser in there, just as long as the little wire goes to the points terminal & the case of the condenser is screwed to the metal body of the mag somewhere.

Thank you very Much

That would be great.

Cheers.

What is the model of this magneto.

Thanks.

I believe this mag is known as a WIPAC model CJ.

BTW, be very wary of "New-Old-Stock" condensers for these old mags. Most of the old condensers, even if they've never been used, will break down internally anyway & probably won't pass an insulation resistance test.

I've done the strip-down of this mag now with all the detailed pictures, plus how to test the mag coil (which can be used on many different mag types). It's too late to write it all up now, but I will do it tomorrow.

"The condensers on these are a special type, but you could put any old condenser in there, just as long as the little wire goes to the points terminal & the case of the condenser is screwed to the metal body of the mag somewhere.."

I'm not sure about that. There are many different types of capacitor (condenser in "engine speak" - in electronics a capacitor).
An electrolytic would be no good for example. I wonder about a high voltage polyester type though, might do, but it has no mechanical attachments. Most capacitors do age, especially those with a paste dielectric, but some don't, for example moving vanes air dielectric, unless corroded.

Am I right in thinking that the main purpose of the capacitor in these applications is to reduce sparking across the points?

I have used 0.22uf 630 volt polypropylene capacitors in 3 of my mags now. All work well and one has about 10 hours running without problems. They do have a plastic case but are smaller then the originals. I glue them in place with wires soldered on going to earth and the points. They are available from RS Components for just a couple of dollars.

I had it in mind they did more than stopped the points arcing. Something about peak voltage??? If thats true a conventional distributor condensor may not be up to the job.

mm5aho wrote:"The condensers on these are a special type, but you could put any old condenser in there, just as long as the little wire goes to the points terminal & the case of the condenser is screwed to the metal body of the mag somewhere.."

I'm not sure about that. There are many different types of capacitor (condenser in "engine speak" - in electronics a capacitor).
An electrolytic would be no good for example. I wonder about a high voltage polyester type though, might do, but it has no mechanical attachments. Most capacitors do age, especially those with a paste dielectric, but some don't, for example moving vanes air dielectric, unless corroded.

Am I right in thinking that the main purpose of the capacitor in these applications is to reduce sparking across the points?

I wasn't talking about capacitors, I was talking about ignition system condensers. I know they are just a capacitor (I recently wrote a long post about putting a capacitor inside the case of an old Wico A condenser) but when we say "Condenser" we mean the thing you find on a spark ignition system, like this....



Oh yes, & you can get non polarised electrolytic capacitors now, you could use one of those I suppose. But I prefer a non metalised polyester capacitor, rated for at least 400v (preferably 500+) at arounf 220-330nF.

But for the purposes of a stationary engine forum, where many members don't have knowledge of these more technical electrical/electronic matters (& where I've gone to great lengths to try & impart a little of my knowledge in understandable terms) we will call a condenser a condenser & a capacitor a capacitor. Where the former is mechanically designed to be installed within an ignition system.

pjjms wrote:
I had it in mind they did more than stopped the points arcing. Something about peak voltage??? If thats true a conventional distributor condensor may not be up to the job.

They do, in theory, do slightly more, but it's still a major point of contention on some forums. But as coil/distributor systems (the Kettering system) was designed after magnetos, they simply carried on using the same thing. Car coil systems work at a far higher HT voltage, so don't worry, car condensers are easily up to the job & are exactly the same thing (in some cases are slightly over-designed) as any magneto condenser.