The Fordson Tractor Pages Forum

hello guys

how do i go about testing a sr4 magneto , I have one that's looks in good nick and want to sell because I have no use for it.

thanks wayne

Hey Wayne,

Quick and dirty* test is to couple all four leads (assuming it has them) together on a single plug, carefully hold orotherwise jam the plug body against a clean bit of the mag body and then click it round on the impulse, if you get a nice fat juicy spark at each click it indicates the mag is generating HT and the distributor is working.

If its been out in the cold, a couple of days on the domestic hot water tank or airing cupboard works wonders

*If there's a crack in the dis cap or insulation problem it may not work at speed

HTH

aye up

it does not have any leads , have had a look inside the distributor cap and it looks like it's never been used.

I will make some leads up and give it a go

thanks wayne

Sounds good from the visual state Wayne,

Don't try a modern(ish) car ign lead as they tend to have carbon rather than wire conductors, (I think its to do with noise suppression and I'm not sure how a mag might be affected), if you have a bit of twin & earth flat grey domestic cable try that, the insulation may not be up to stopping you get a belt if you touch it

I don't know what they're worth but you see some hopeful asking prices in the comics -

I've just brought home an old Bosch which came off one of our Standards and has lived under Dads bench for the last 40 odd years, used to test plugs and light the gas torch Has leads but is pretty grubby so when I have a quiet half hour I'll be following your lead - when I was a kid I used to put a heavy pencil line along a board, bang in a nail for the leads (tied together) and with an earth wirefrom the body connected to a drawing pin see how long a spark I could draw out, yup had my share of shocks then I discovered Van der Graaf generators and induction coils, the fascination never left and I'm currently gathering bits for a trial build of a Tesla coil which can deliver sparks feet rather than inches long, (will need to exchange the usual asbestos undies for some in chain mail which can be earthed

Good lock

Rick

cheers for the info rick

I got a bit of twin core and did like you said , she sparks lovely , got our lass to hold the wires so I wouldn't get a belt

how much are they asking in the comics , I've got it on eBay starting price of £50 don't know if it's too much or too less to be asking?

thanks again wayne

Hi Wayne,
Whilst the results of your tests are encouraging and certainly indicative of a healthy magneto the true test would be to put it on a tractor and get it well warmed. I've seen spark dwindle and fail when they get warmed up under use. However I don't think your £50 starter isn't too bad for the above reason and anyway you want to get a few people interested in it to get the bidding going.

I see a lot of stuff on Ebay getting repeated time after time when similar items are selling like hot cakes cos they are pitched at a more reasonable price.

Good luck with the sale.

Regards,
Derek