• Tim Wadsworth
    13 December 2007 at 20:59 #47044

    I have the original 1931 hand book for my 2 litre and the photo of the magneto looks very much like a BTH. On my first rebuild I fitted a post war Lucas. This did great service for some 30 years until the plastic gears stripped (during a wedding!) I then fitted a pre war renovated BTH and bought a matching spare. These were never trouble free especially when I raised the CR. Finally a couple of years ago I bought a pair of Scintillas and they have been perfect. The car has never failed to start first touch of the button. In all cases the shaft centre hight is the same but the Scintilla is about an inch taller than the BTH and so I had to remake the straps – not a hugh problem.

    14 December 2007 at 16:49 #47051

    The 2L Lagonda Owners Manual mentiones the name Scintilla and the picture clearly shows the type number on the housing – either MN4 or (more likely) GN4. I do not have my handbook (or even my car) here so I cannot 100% confirm the type but Alan Fairbrother will know. I bought two of these (restored) from him and they are exactly as pictured.

    15 December 2007 at 11:12 #47059

    I have now had a chance to look at the 2L Low Chassis Instruction Manual and the Magneto pictured is the Scintilla GN4. I am sorry for the confusion. As I said, Alan Fairbrother can provide one, either restored (recommended – Alan is very good) or unrestored.

    Stephen Matthews
    17 December 2007 at 20:26 #47075

    Bob, Happy for you to have it if you wish. Please contact me on my email ; [email protected]

    kkind regards,


    4 June 2009 at 21:51 #47578

    Finally I have installed the BTH GA4 in my 2 litre and it gives a good spark with no trouble yet.
    The Scintilla is definitely not suitable for the 2 litre ;too big and impossible to fit under the hood.



    5 June 2009 at 11:32 #47580

    I’m glad that you’re happy with the BTH magneto you installed in your 2 Litre – and I’m sure it’ll work well on the car.
    However, the remark that a Scintilla GN 4 is “unsuitable, too big and impossible to fit under the hood” on a 2 Litre Lagonda is nonsense.
    This particular magneto is actually recommended and described in the 2 Litre owners’ manual, my car has been fitted with one for 76 years and it fits and works perfectly. See picture.

    Attached files

    5 June 2009 at 14:34 #47581

    Sorry for that; I would have to say:
    “….unsuitable, too big and difficult to fit under the hood” on MY 2 Litre Lagonda”


    5 June 2009 at 16:33 #47582

    I presume that by “hood” you actually mean “bonnet”, but I still do not understand why the Scintilla GN 4 wouldn’t fit; it is not a particularly large magneto and, as I said, described in the original manual and fitted on many 2 Litres.
    What kind of a body does your car have?

    5 June 2009 at 19:10 #47583

    The fixing plate for the magneto is such that the clamping would pass over the bakelite part .In fact I would have to change the plate holding the magneto .This would certainly allow me to fix it;- in fact not a major difficulty,but the ML and the BHT are simply interchangable.

    Colin M34
    6 June 2009 at 07:34 #47584

    Hi Folks,

    I eould like to add to this debate. I use an ML magneto on my 2 Litre and I like it very much. I also like Scintilla magnetos, and some years ago bought a Scintilla GN4 for my 2 Litre. In my opinion the GN4 is a large lump more suited to a commercial vehicle rather than the 2 Litre and I have just sold it on eBay – http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=330328442857 .

    By the way if you don’t know, “G” stands for Grande – ie large. It is and I don’t think Lagonda recommended a “G” Scintilla on any car. 16/80s used a PN6 (P=petite), and my M45 has an MN6 which is half way between the two. 3 Litres use them as well – running at 2/3 engine speed not 3/4.

    Scintilla PN and MN magentos are very expensive to buy now and before I bought it, my 16/80 was robbed of its PN6 and an 6 cylinder ML put in its place. Actiualy I don’t mind because ML magnetos are easy to work on. One important feature is that there is a chamber where a standard capacitor can be put – they do go faulty. Also the coil is easy to remove and can be re-wound quite cheaply.

    I would strongly discourage anyone with a 2 Litre from using a BTH rotating coil magneto (of the type used on a Rapier) – certainly without having it re-wound. This is because the coil on the armature was originally impregnanted with shellac and when older magnetos get hot the shellac runs out and causes it to seize. This will result in your fibre timing gear being stripped and the car being immobile.

    Keep sparking folks

    Colin M34

    6 June 2009 at 08:23 #47585

    I have a Scintilla GN 4 on my 2 Litre and a spare one in the boot (from Alan Fairbrother whom I mentioned before), not only because the car came with it but also because there is a 2 page description and user guide for this very magneto printed as “addendum” in my copy of the Lagonda 2 Litre Owners Manual. That means that Lagonda recommended this magneto, and indeed, it is not a “large lump” at all but fits perfectly; the holding plate and clamps are exactly the correct size (see the picture in my previous posting). Certainly, there are smaller magnetos but these would not fit as well on MY car, I would have to change the holding clamps etc. Also, I have seen 2 Litres with magnetos larger than my GN 4. I add a picture, I do not know what marque magneto this is but it’s significantly “lumpier” than mine. Still, it seems to fit.

    Attached files

    7 June 2009 at 15:47 #47586

    @ oakley
    could you please take a picture from above onto top of your Scintilla GN4 to show how clamping is arranged…?
    many thanks for that


    Colin M34
    7 June 2009 at 21:09 #47587

    Hi Folks,

    An interesting debate. The large magneto shown in Oakley?s latest photo is what we call a ?big Simms?. The person from who I bought my 12/50 Alvis used to swear by them They are a large ?lump? but there is plenty of space for one in the 12/50.

    Clearly users have their favourite magneto and frankly I feel there is not a ?right? or ?wrong? answer.
    As for Scintillas as original equipment on Lagondas, I have a theory. In the 1930?s the company finances were very shaky and I?m sure that many suppliers had to be patient before they were paid. M45s, for example, used either BTH or Scintilla magnetos and I suspect that this was as much a commercial as a technical choice ? they are both fine units and perhaps in 1933 Scintilla refused to extend any more credit to Lagonda Ltd and BTH gave a good price for a number of units. Or maybe Lagonda bought a job lot of BTH units when Invicta went bust!

    Certainly, Lagonda Ltd liked Scintilla units, a view shared by both me and Oakley. Because they made most of their own parts, there would be no problem making different fixings to suit the different makes of magneto – I have two types of clamp for my M 45.

    I look forward to examining Oakley?s car to see how well the Scintilla GN 4 would fit on a 2 Litre. The unit I sold on eBay made ?63.75 so clearly it was a bargain compared with the smaller Scintillas which can easily cost ?200 before reconditioning and ?500 in full working order. So if you can live with the size of a GN 4 you will get an excellent magneto at a reasonable cost.


    8 June 2009 at 06:38 #47588

    At Bob’s request I will try to upload a few more pictures of my engine with the Scintilla GN4 and the clamps etc. sometime after this week – at the moment I am not in England.
    However, on the picture I provided you can see the spring-steel clamps and the single bolt on top which tightens the clamps perfectly around the body of the magneto. The width at the bottom is also exactly that of the magneto so there can be no lateral movement. The bottom plate is fixed on the engine with three large “sunken-head” bolts.
    This fitting is both solid and simple; changing the magneto on my car is a matter of only a few minutes. (Don’t forget to mark the crown wheels and coupling individually for both magnetos though – using different colours paint is the most practical way).
    Although, as I said, I carry a spare in the boot of my car I have never had to use it. My Scintilla GN4 always works fine – but Alan Fairbrother put a modern condenser inside which lasts forever, unlike the original ones.
    I bought the spare GN4, completely restored, for 350 pounds three years ago – not very cheap, but today they cost 450 pounds from the same supplier. I bid on an unrestored (but very nice looking) one on Ebay last year but my offer of 155 pounds was not enough…..
    Interestingly, I asked Alan Fairbrother about the “big Simms” and he says that they are actually designed for use on busses, and do not perform well above 3000 revs! That seems unlikely to me as one is fixed on a Lagonda which apparently runs fine. But Alan is a great magneto expert and the size of the thing certainly suggests that it is for use in larger vehicles.

    9 June 2009 at 15:31 #47589

    Here a picture of the BTH matching perfectly the 2L engine bay

    Attached files

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