auto advance Lucas distributor springs

[Chris KC]

I would suggest that some of that information maybe misleading, dependant on engine spec we want to be at full advance somewhat higher than 1000 RPM, this figure will be distributor speed. I also disagree with Jim, sorry Jim, that the light spring should be fully extended at idle, but agree its influence is greatest at very low engine speed. My experience is that if you can eliminate play in the DK4 mechanism, which requires new parts or an ability to remake and or bush the old ones they work well, the most difficult problem to rectify was wear of the pins, fortunately new parts are now available, re-bushing the quadrant and body is also often necessary.

Must admit I was thinking much the same on the walk home tonight Ian. If you are going to set max advance at 1000 (engine) rpm - scarcely much above idle - then why bother with auto advance at all.

[Tony Press]

ok, so who actually was Andy DeLuvian in reality, and is he still around?

I also note that Bruce White wrote about Austin 7 automatic advance curves and trials with a NOS Austin 7 distributor spring set. Is he still around?

We haven't heard from Bruce from WA for some time- check the old forum. 


The clue might be in the name ' your colonial correspondent'.

Cheers, Tony.

[AustinWood]

The light spring is not fully extended at idle. However the heavy spring is loose at rest and only the light spring works initially. Once the heavy spring comes into play its effect far outweighs the light spring and controls the advance.
ie It is a 2 stage process. I think this emulates the manual system where the ignition is retarded to avoid kick back then advanced when the engine starts.
This is certainly how the Ducellier distributor works on the Citroen SM V-6 Maserati engine. The initial timing on this engine is after tdc and advances to 20 degress before tdc at 2000 engine rpm.
The pictures of the accuspark distributor show that it does not operate this way having 2 similar springs. I don't know what the original DK4 specification is.