Distributor Advance Springs

[JonE]

https://www.ebay.co.uk/itm/325188109601?...37EALw_wcB

Wonder what these would do... 30p each.

[Graham Barker]

I have settled in my mind the correct spring selection.  I asked the Distributor Doctor to send me the correct springs for my model of distributor (Lucas DK4A 404440).  Two identical springs arrived in a Lucas packet with 404440 marked on the packet.  So that would indicate that use of a light spring and a heavy spring was not correct for my distributor.  I have fitted these new springs.  They pull the weights completely back together when at rest (this was a problem with the previous springs). Have done some trial running to set optimum timing and the car pulls better than ever.
I hope this is helpful to others who have some doubts about distributor spring selection.
Regards
Graham

[JonE]

Graham, what sort of movement back is there when you move them outward? Do they snap? What sort of finger pressure moves them outward, descriptively?

[Denis Sweeney]

Interesting, my DK4A had differing springs and on enquiring was advised they were correct……

[Graham Barker]

There is a plate below the weights with holes to take the stubby pins that stick out of the bottom of the weights. These holes have become a little oval with wear. This results in the weights having a little bit of slack in the at rest position. Consequently the weights do not quite smack into each other when they come to the at rest position. The springs are quite strong. I found it difficult to pull the weights apart with my fingers. It was necessary to get a screwdriver between the weights to move them apart. 
Cheers 
Graham

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Well Dennis, that opens up the confusion again. Anyway, I am happy with the identical springs. 
Cheers 
Graham

[JonE]

The springs are quite strong. I found it difficult to pull the weights apart with my fingers. It was necessary to get a screwdriver between the weights to move them apart. 

wow - that is substantially different from my new old stock unit. Two finger twist of the rotor arm gives easy movement and snap back. Perhaps there is more leverage from rotor arm though.

Anyway, you found an improvement, so all well.. but there is clearly some variation out there.

[Graham Barker]

Oh. I didn't check by twisting the rotor.

[Ian Williams]

The wear in baseplate holes is usually on the advance side so should make no difference to snapback, it will however alter the amount a distributer advance so you may need to look at that. I think that your snapback issue Graham is more likely to be due to the wear in the pins on the advance weights, and in the toggles that attach the springs to them. I would also suggest that if you need prise a screwdriver in to move the weights the springs are either too heavy or you have other undiagnosed issues. You may have noticed an improvement in performance because you are effectively now running a fixed distributor and no longer suffering timing scatter. You may notice a further improvement if you resolve all the problems you probably have in your distributer and get it working like a NOS unit would.

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Have you checked to see that the distributer is actually advancing in use Graham?

[Graham Barker]

Hi Ian and JonE,
I have now tested the operability of the advance mechanism by twisting the spindle. This is easy to twist as you and JonE suggest it should be. On release of the spindle the weights spring back into place, almost touching. 
When I twist the spindle I get about 2 degrees of free play and then 6 degrees moving the weights out. So this means that I am getting 6 degrees of advance at the spindle corresponding to 12 degrees at the crankshaft. The free play is resulting from the ovality in the holes in the supporting disc that I mentioned.
I can live with that for my purposes of cruising in my Ruby. 
Regards 
Graham.