DJ4A distributor advance springs

[John Gould]

No Robert, in overall shape yes but the contacts are the more modern style with different mounting and clamping points.

[JonE]

not the right serial number, but comes up with link to Austin 10...
https://www.ebay.co.uk/itm/393160949481?

[Parazine]

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..!

John, it looks like your distributor is from an earlier, unknown type of car (5 33 is the date, i.e. May 1933). Perhaps your best course of action would be to find an example of the correct Ruby distributor, DK4A, for which spares are available from Distributor Doctor and others. 405508 is the magic number for an 8 degree DK4A, like the one in the pictures. They come up on eBay from time-to-time or advertise in the "parts wanted" page of this forum.

[John Gould]

I expect you're right Parazine, a DK4A is probably the way to go. 
However I'm confused about the number of distributor degrees advance the A7 engine requires, my engine (number M184958) is a 2 bearing one so from what you tell me it presumably needs only 3 distributor degrees (6 crank degrees) advance. This is about what I think my distributor is actually delivering.
The engine runs well enough but misfires a bit at high revs and I feel the power drops off - I always start by looking at the ignition side but maybe it's more like plugs/carb etc.
Might I be right in thinking I therefore don't really have an ign. advance problem?

[AustinWood]

I gave up with the DK4A and fitted an Accuspark distributor that works very well. This is my everyday car so functionality is more important than originality. I have the original distributor.
Even with a lot of new parts the Lucas unit never worked very well. Accuspark was a revelation!

[Bob Culver]

Note that the static setting for the two distributors differs so that the final advance is not so very different. Further confusion arises from the early Ruby handbook error and repeated in a myriad other publications giving the manual static setting for an auto distributor.