One of the springs in the distributor on my Brum Scott is broken, where do I get “new”?
I have tried Graham, but he couldn’t help.
The distributor is a Lucas DKX2A, type AX1, Lucas number 40178 D, serial number (I guess) 1249, (springs are Lucas part no 416627).
There were two different springs I don’t know if this was correct.
There is some guy called the Distributordoctor, but he hasn’t answered.
The Sunbeam S7 and S8 specialists Stewart Engineering sell most of the bits for the Lucas DKX 2A distributor as it was fitted to both of those models.
Thank you Brian, but there were seven type of DKX2A distributors accordig to this swedish “manual”, with different weights and springs, and advance.
Thinking about this and trying to apply a little logic, I would think that because the distributor spins at engine speed on the Scott, and at half engine speed on the Sunbeam S7 and S8, the springs would need to be stronger, or the bob-weights lighter, on the Scott in order to prevent the distributor going onto full advance too soon. I’ve just pulled that thought from the grey matter in my brain, and perhaps I am mistaken in that little theory, but I don’t think that the springs from Stewart Engineering would cost much, and maybe it is a case of buying them, fitting them, and then trying the bike to see how it behaves. I have always found that longstroke Scott engines seem to be very unfussy about ignition advance and retard, unlike shortstroke engines, which react well to magneto control. I therefore suspect that the bike will run perfectly well with virtually any of the various grades of spring that used to be available!
Somewhere, (can’t find it at the moment), I have a Scott/Lucas leaflet printed in 1950, which gives all the relevant data for the DKX2A distributor, including the revs at which full advance should be attained. When I find it I will post the details on this website. Armed with that information, you could then hook up the bike to a garage test machine , Crypton, Souriau, or similar, and see just exactly what is happening with the distributor as the revs increase.
However I suspect that even if the distributor was fixed onto full advance, you would be perfectly happy with how it runs….
It should also be noted that a virtually identical distributor, but fitted with a four cylinder type cam and cap, was fitted to countless prewar cars in the UK, notably the Ford Model Y “Tudor”,and late model Austin Sevens, and I’m sure that various vintage/classic car spares specialists could also supply these springs.
I hope that my rambling will help you!
Perhaps the car one you mentioned above was the DKX4 as fitted to Austin 7’s etc and also Ariel Square 4’s. I have a Scott that had one fitted, converted to turn at half engine speed and with two plug leads going to each cap (ie 1 and 3 to one plug, 2 and 4 to the other) due to it turning at half engine speed. It of course therefore advanced the ign twice as much as it should have and ran horribly over about 4000rpm due to over advanced timing. I’m sure that was one contributor to a broken crank in that engine. I have since binned it and put a Lucas magdyno with cable advance operation onto the bike and it runs much better.
As for distributor springs and advance weights they get a seriously hard time at engine speed and wear badly. That causes irratic spark timing (try strobing a Scott and see as you rev it) so the best fix I have found as Brian mentions is just lock it and set the timing at 1/4″ to 5/16″ BTDC.
The following info is taken from a Lucas Leaflet “Motor-cycle equipment details and spare parts for Scott 596cc Flying Squirrel 1950”.
The correct auto advance springs for a Scott distributor DKX2A are number 416627 and the weights are part number 415729. Centrifugal advance commences at 300 -500 rpm (distributor) and gives maximum advance of 17 – 20 degrees at 2,900 rpm.
thanks to all, it became quite interesting. I have allways collected what I came by of springs. I had one of approximately the same stregth, and made it fit. Checked with tachometer and stobo-light it looked right.
But, New topic!
While involved with the Spares Scheme a while back we did have a batch of distributor springs made in conjunction with Price Productions of St Neots. He was specialising in the repair of distributors however I do not know if he is still in business. The telephone number was 0148 473225. Hopefully he will have kept up stocks of these springs if he is still around. There are two different springs for the Scott distributor. I will send you a rough sketch as I don’t seem to be able to attach an image on this message.
I have taken the liberty to upload Jon’s drawing:
The wire on my broken spring is only .035″
Price Productions is still in business and advertise in the Old Bike Mart on the front page. He wiil be able to supply the correct springs. The address is 14,Heron Court, St.Neots, Cambs. PE19 1TH .Tel.01480 473225. He reconditioned my Scott distributer 2 years ago which was suffering from a worn shaft and bushes and made an excellent job at a very reasonable price.He is not on the internet and is an old fashioned businessman, he sent the distributer back and then the invoice. Ted.
I have just had a DKX2A restored by Distributor Doctor, Martin Jay 01398 361678
I have been very pleased with his work (the usual disclaimers apply). He was knowledgeable, and prompt with delivery. And the unit came back with a graph showing the original performance and the finished result, which ran up to 19.5deg at 4,500 rev. If I could work out how to attach a pic I would enclose it – but if anyone wants a copy, please email me. email@example.com
The result on the bike is excellent. Not only was the bearing badly work, the weights and springs were wrong, and the cam was 3 deg out, the base plate had a hairline crack. Oh, and he has added a lube point for the shaft.
Value? £273 but it’s like new – and you can’t buy one of those can you?
To me he answered, that he didn’t have the springs. Have written to Price instead
Hi, I have just checked and Roy Price overhauled my distributer in 2007 and charged me £42.00. Ted.
When I contacted Price about 6-8 months ago he had stopped doing distributor work.
Jon Hodges spring dimensions look very similar to two Scott distributors I have. I’ve always been puzzled by the odd springs, one relatively light but the other a very heavy wire. The heavy one is out of contact with its pins at rest so can only come into play after a certain advance and then it must dominate the advance control thereafter. I asked Price if he could explain this to me and he said “Ask Mr Lucas!” I have tested the advance curve with a strobe ( but no rev counter ) and as far as I could tell it goes to maximum advance of about 12 degrees as soon as the throttle is opened beyond idle. It was also quite unsteady as commented by Brian Marshall. The advance curves of alanw1947 ‘s distributor, before and after overhaul by Distributor Doctor, are revealing as “before” – 13 degrees advance from less than 1000rpm and completely flat thereafter confirms my own approximate observation – “after” shows a progressive advance up to 19.5 degrees at 4500rpm.
Brian observes that the longstroke engine is relatively insensitive to advance/retard and functions well on a fixed setting, but you have to accept that it will four-stroke merrily at idle. That may not bother you. Several owners of coil ignition models from the distant past have enthused about the very smooth idling and light throttle running to be had by retarding the ignition by 20 degrees or more. This was achieved by lever control of the distributor body – and usually retaining the auto-advance feature as well. Sam Pearce used a twistgrip control on the left side of the handlebar giving 20 degrees ( plus 12 -13 deg auto ?) Roger Wheeler ditto with a handlever – Technicalities 5.3.01 Connell in the 40’s on the Victor Scott used even more for very slow steady tickover. My ex-Lofty Avis 49er with lever control confirms this finding – four-stroking can be just about eliminated. You may find a bit of trouble with engine overheating at the more extreme retard level as the poor combustion efficiency requires more throttle. Its the extra fuel going in that extends the two-stroking range but it also heats the pistons up. So, moderation is probably advisable.
I keep learning, thank you Mike. I have been playing with the idea of manual advance.
I have taken the liberty to publish Allan’s advance curve: