DK4A WEAR OR NOT ?

[Peter Clayton]

I would like some advise as to whether my advance control plate in the distributor is severely  worn or has it been modified to give extra advance. The plate hole extensions appear to be too even and symmetrical  to be wear and there is no wear on the bob weight pins. Has this been seen by others? Total advance would be around 20deg according to my strobe light and on the road the car seem to perform reasonably well. I know if it ain't broke I shouldn't mend it. but wouldn't want to be putting the crank under unnecessary strain. As an after thought, should the bob weight springs be identical or one light and one heavy to give the best advance curve. (Who's going to be first to tell me to fit a BOSCH? )     

[AustinWood]

I think that 8 degrees of distributor advance would give 16 at the crank. Your strobe seems to confirm this.
That plate looks in surprisingly good condition, so it's likely that your DK4 is working well. Unusual I think.
I got new springs from the distributor doctor. One was lighter than the other. The various old distributors I have seem to have both springs the same.
On another car we have a more modern, 1972, distributor (Not Austin). That has one weak spring and one strong. I think the reason for this is that at cranking speed there is no advance, but as soon as the engine fires the weak spring is fully extended, hence advancing the ignition. Thereafter the strong spring takes over. This automatically retards the ignition for starting.
We gave up with the DK4s, they were all very worn. Now have an Accuspark which works very well. Having all new mechanical advance mechanism is a big advantage.
I tried a Bosch, it was a disaster. I believe the Bosch look-alikes are to be avoided.
If the strobe shows a gradual advance then it must be working well. I suspect that worn ones don't advance properly.

[Ruairidh Dunford]

I find the Bosch units too harsh, even with the stop modified.

I have some original spindles here that you are welcome to try, if you want.

[Steve Jones]

..................I believe the Bosch look-alikes are to be avoided..................

Not necessarily. All depends which Bosch look-alikes you buy, where you get them from, how they're modified to fit a Seven and who does it.

Steve

[Reckless Rat]

I have a Bosch 009 on my RP which came from Willie McKenzie. It has been working perfectly for the last 15 years.

[Peter Clayton]

Thanks for the replies gentlemen, After  stripping  the gear and removing the spindle, I  welded the worn areas and filed  the holes back to 8.5 mm  diameter. Now reassembled the engine is running smoothly but as there was some free play in the bob weights and the springs slightly stretched , I'll run it as is at present but will be looking at getting a 009 unit and possibly electronic operation to help smooth out any roughness in operation.

[Bob Culver]

For distributors where the springs hang slack as many did as new there is a marked difference between hand cranked static advance and low speed advance as per a timing light. if the weights and pins not seriously worn, some idea of max advance on car can be obtained by locking at full advance with a washer and long screw down the middle, all twisted and locked at full advance and hand cranked. The hard part is finding a long correct thread.