DJ4A distributor advance springs

[John Gould]

Just wondering if anyone knows of a source for Lucas DJ4A springs, Unfortunately the Distributor Doctor can't supply them - perhaps a cherished supplier?
Thanks, John.

[Parazine]

John, the DJ4 doesn't have any advance springs, the timing is fixed. The springs are part of the centrifugal advance mechanism, which was introduced with the DK4A in the summer of 1934 when the cowled radiator cars were introduced.

Distributor Doctor supplied me with DK4A springs a few weeks ago.....

[GaryCullen]

My 1933 A10/4 came with a DJ4A distributor. As is referenced elsewhere.
On investigating my lack of power out on the road I found balance weights below the points plate.
Broken springs and stuck down the side of the weights is what my problem was so no advance as revs built hence no power. The weights were stamped 8 degrees. I filed the holes out a bit to give closer to 10 degrees.
I got a selection of second hand springs from The Distributor Dr and the smallest set was perfect.
So maybe just for A7 no auto advance . I assume manual though.
Regards

[John Gould]

Thanks folks, I do also have a DJ4 and that's just as Parazone states, but this distributor has DJ4A stamped on its plate followed by the number 7, that's probably the degrees of advance as its baseplate is stamped 7deg. Actually the distributor is in pretty good condition but the auto advance springs have stretched slightly and that, along with a bit of accumulated wear here and there in the weights mechanism, means I'm only getting very slight sprung movement on the cam spindle, certainly nowhere near 7deg. If I can't get new springs I might indeed need to open out the baseplate holes and time it to max advance as suggested in another thread, but I'd really rather keep that as a last resort.
I guess the DJ4A is an interim distributor and if so I'm starting to think a pair of DK4 springs might be just what I need - does anybody know if that is so?

[JonE]

perhaps post some internal photos so people can compare what they know of the DK4?

[Parazine]

Interesting - I was only aware of the DJ4 and the DK4A (below, left and right) being used on Austin 7's with the changeover in July 1934. Any other distributor (DKY4A, DM2 etc) was probably introduced by the special builders in the 50's and consigned to the Autojumble box.

   

Perhaps this mysterious DJ4A was an interim model or more likely, standard fitment from another car entirely? 7 degrees is not a standard Austin 7 advance figure, 3 degrees for 2 bearings rising to 8 degrees for three bearings were the standard figures.

There's very little/no reference to a DJ4A on the net.

[John Cornforth]

Hi

As far as I know, the model number is made up as:

D = Distributor
J = Model
4 = 4 Cylinder
A = Auto advance

The A in distributor model numbers was dropped in later years when auto advance became universal.

Lucas model numbers like DJ4 and DK4A are only the start. From some time (probably in the 1930's) due to the multiple variants within each model Lucas also used a part number of 5 figures plus a variant letter. The variant letter was for minor production changes over time, and doesn't normally affect interchangeability. Only with this part number can you reference the detailed characteristics.

Probably also worth noting that Lucas convention was always to quote "Distributor Degrees" and "Distributor RPM" in their data, so 7 degrees advance range at the distributor is 14 degrees advance range at the crank. Baseplates are often stamped with a number representing the distributor advance range.

Lucas convention for rotation (CW or CCW) was to define it looking at the driven end, NOT as viewed from the rotor arm. This has caused some grief over the years.

[Parazine]

Lucas model numbers like DJ4 and DK4A are only the start. From some time (probably in the 1930's) due to the multiple variants within each model Lucas also used a part number of 5 figures plus a variant letter. 

The DK4A pictured above has a plate numbered:

   

and the DJ4:

   

Number is 56762

I believe both of these to be genuine Austin 7 distributors but my Lucas catalogue only deals with post war reference numbers 

[John Gould]

Thanks for all the info.and suggestions and if I can figure out how to pull the right levers in the correct order I'll pop a couple of snaps on here.
The pic shows the springs at rest, just before they take up tension. The distance between the centre point of the fixed pin for the outer end of each spring and the centre of the tiny spring receiving hole in the moving pivot is exactly 0.50".

Also the other numbers I can make out on the battered plate are; BN9-2,   533B,   21812.  They might just mean something to someone.

The distributor came with the engine on the rolling '37 Ruby chassis I got a couple of years ago, there's certainly no suggestion that it was ever original to the chassis or even the engine or even an A7 for that matter..!

[Robert Foreman]

John, 
   does the baseplate on your DJ4A look like this with the earlier style of contacts?