Lucas DX2A distributor NEEDED.

[twolitre]

Hi, I am in desperate need of a Lucas DKX2A 15 degree range (whatever that means) distributor for my 1957 Triumph 5TA Speed Twin.  I also need the 3 hole mounting flange and (probably) the drive gear. Can you help?
  The part number is 40352D. Although the same bob-weights are listed for the 6T Thunderbird the degree range is given as 12.5 degrees and the unit part number is different. Can anyone tell me whether the 6T unit can be modified to suit?  Or even if the required type is used on any other bike?
Jim Walker - jamesrambler@hotmail.co.uk  

[L.A.B.]

15 degree range (whatever that means)

The "degree range" is the advance range of the distributor AA unit.

As the distributor rotates at half crankshaft speed that 15 degrees equates to 30 degrees of *crankshaft* advance.
The 6T unit would only give a 25 degree advance range, so it could work, but you won't have the full ignition timing advance range between idle and full advance. However it may well be possible to modify the 6T advance unit to give more range?  

[L.A.B.]

Further to my previous message, the two distributors appear to be more-or-less  identical, including points cam, AA bobweights & springs, the only difference appears to be the "shaft and action plate".

The 40352E DKX2A 5T type has a 421414 item, and the 6T 40449A DKX2A is a 421935.  

[twolitre]

Thanks, L.A.B.  I imagine you know why I want a distributor. It is in fact the advance characteristics of the twin contact (non-Lucas) distributor fitted which is bothering me. I think the odds are against it matching the required advance curve and I have the horrors at the thought of bright blue exhaust pipes if retarded or holes in pistons etc. if over advanced.
Jim walker.

[L.A.B.]

It would appear there were quite a few variations of *DKX2A* distributor, as they were used on a fairly wide range of motorcycles, and not just Triumphs, so specifying a DKX2A may not actually lead you the correct 5T (or 6T) item?  

[twolitre]

Thanks L.A.B., I have given all the info I have been able to track down in my first posting and the part number is from a Triumph Parts Book.   However there might be a possible, but not age authentic, alternative.  Triumph Twin Spares are offering a THUNDERBIRD 18D2 distributor complete with mounting flange and gear.  Presumably for a later model and from the pictures definitely pre-unit.  If a suitable 18D2 was used on later (pre-unit) Speed Twins, I would settle for that, but I have no information.
Jim Walker

[L.A.B.]

I have given all the info I have been able to track down in my first posting and the part number is from a Triumph Parts Book.

OK, however the 40352*D* would be correct for a 1956 5T.
40352*E* being correct for your 1957 model, not that it matters much I doubt, just that the E was the later (maybe improved?) part. And I will see what I can find out concerning the 18D2 type.

[L.A.B.]

However...there appears to be at least eleven variations of *18D2* distributor with different advance characteristics!

[L.A.B.]

18D2 type 40690 (A or B) I believe would be the 6T item.

[twolitre]

Handbook 17,which I have, covers 1956-59 for the 5T and shows no variations in bore/stroke, compression ratios, valve timing lead/lag or anything else significant for the 5T.  However, it also stops with the 1959 5T, but continues with the 6T into 1960. So it is possible (likely?) that the 6T gained its 18D2 after the demise of the 5T?  The Handbook shows nothing but DX2A fitted to either.  If so the 18D2 looks like a dead end.
Jim.

[L.A.B.]

The 6T 40449A/B DKX2A was specified up to 1960.

18D2 type 40690B is listed for the 6T from 1961