Magneto

[Roadhog]

Hi, can anyone help which is the correct Magneto for my 1952 A10 PLunger. it currently has a Lucas  K2F, which is manual advance and retard ( lever and cable type) My handbook is saying that they are all K2F with automatic Advance retard , (no lever or cable) which is correct? Thanks

[Greybeard]

My Plungie GF from 1955 has auto A&R. I'm 99% certain that that is original.

[groily]

Lucas Parts Lists suggest 42248 E for the original mag for GF for those years - with fixed camring, and clip on bakelite cb cover with tangential take-off lead for remote engine stop. Plus an ATD.
So the book is right I reckon, if you are looking to get to the original specification.

[Roadhog]

Thanks , that helps, I now need to find a good recon auto mag. All the best.

[RichardL]

According to Bacon, 47-51 A7, A10 and A7ST automstic. All years A7SS, A10SF, A10RR, A10SR, A10RGS and A10 Spitfire manual. 52-54 A7ST manual.

Not sure how this fits with Groily's post while I was typing.

Richard L.

[Roadhog]

Thanks RichardL. thats confused the matter, mine is 52-March. 

[Greybeard]

Thanks , that helps, I now need to find a good recon auto mag. All the best.

I suggest contacting Priory Magnetos

[RichardL]

Thanks RichardL. thats confused the matter, mine is 52-March.

Just quoting Bacon's book, not swearing by the accuracy. I'll check to see if I've left something off the list. Not posting copy due to copyright.

Richard L.

[Black Sheep]

I am fairly certain that yours should have an auto-advance. However, people opted for manual for 2 reasons. Firstly, if they wanted to fit a rev counter. Secondly, to take control of the ignition advance. There are good reasons for this. Not being a stickler for originality, I changed both my A7 and A10 to manual.

[groily]

 All years A7SS, A10SF, A10RR, A10SR, A10RGS and A10 Spitfire manual. 52-54 A7ST manual.

Not sure how this fits with Groily's post while I was typing.

Think it fits Richard because (A7SS) and A10s Super Flash, Road Rocket, Super Rocket, RGS and Spitfire were manual but GF wasn't I don't think. Parts Lists may only say some of the truth, but if you scroll down to page A15 in the Lists here http://www.brightsparkmagnetos.com/library/Parts%20lists/Lucas%20motor%20cycle%20parts%201936-57/A03-34%20Equipment%20specification%20by%20machine.pdf, you'll see what they said for GFs for the relevant years, and then if you scroll through the interminable magneto lists also published in the day, you'll get the spec for the exact models mentioned for the bike, with precise details. Same mag for all years bar year 1. Really quite hard work and needs sharp eyes and not too much wine-assist to plough through. The info is there - but whether it means 'no other sort was fitted', that's a whole other question and I dunno.

If looking for a good fixed cam mag, and if you're being a stickler for the details for this particular bike, you might want to get one with the chamfer on the engine side, lower surface. Helps with the fit of the long lower 'nut', although I think pretty well any K2F might go on OK. (But haven't got a plunger model, so not sure if it makes a real difference or not.)

[Roadhog]

Thanks everyone, so far it looks like the standard GF for 52 was an auto unit, and all the sportier models had manual. I have a good manual mag so wondering if it makes any real difference sticking with it. I do want original if I can. not sure now.   

[RichardL]

Thanks RichardL. thats confused the matter, mine is 52-March.

Just quoting Bacon's book, not swearing by the accuracy. I'll check to see if I've left something off the list. Not posting copy due to copyright.

Richard L.

Apologies for trying to shorthand Bacon's statement. I did find a mistake in what I said. This is the correction:

• For all years of A7 and A10, automatic
• 47-51 A7ST, automatic
• For all years A7SS, A10SF, A10RR, A10SR, A10RGS and A10 Spitfire, manual.
• 52-54 A7ST, manual

Richard L.

PS on my BS --- In my rush to correct myself I failed to read Groily's most recent. Always believe Groily over me, or in general.

[beezermacc]

Thanks , that helps, I now need to find a good recon auto mag. All the best.

I suggest contacting Priory Magnetos

Thanks Greybeard. I have one in stock!

[olev]

Gday Richard,
With regard to copyright, in Australia we have a thing called 'fair dealing' which allows you to use copyrighted material provided you don't run amok.
They might call it 'fair use' in the states.
cheers

[BSA_54A10]

Thanks RichardL. thats confused the matter, mine is 52-March.

Just quoting Bacon's book, not swearing by the accuracy. I'll check to see if I've left something off the list. Not posting copy due to copyright.

Richard L.

In theory, if BSA / Lucas got the springs & bob weights correct then the auto unit will be almost timed correctly over most of the rev range.
A manual one will only be correct over a very small rev range

Apologies for trying to shorthand Bacon's statement. I did find a mistake in what I said. This is the correction:

• For all years of A7 and A10, automatic
• 47-51 A7ST, automatic
• For all years A7SS, A10SF, A10RR, A10SR, A10RGS and A10 Spitfire, manual.
• 52-54 A7ST, manual

Richard L.

PS on my BS --- In my rush to correct myself I failed to read Groily's most recent. Always believe Groily over me, or in general.