Points plate moving freely? Is this correct.

[Arthurdaily]

Good Afternoon everybody. Now, I have just serviced my minor and realised that the vacuum advance is not working. So, I took off the distributor and took off the old vacuum advance unit - but I noticed that WITHOUT the vacuum advance the 'plate' that holds the condenser and points etc has no 'spring' action, ie I can simulate the advance by moving the plate but it DOESN'T then spring back, it seems that it is the action of the vacuum unit (now dis attached) that pushes it back - is this how it is SUPPOSED to be? If so what are the springs underneath this plate in the bowels of the distributor supposed to do?.

Thank you in advance.

[bmcecosse]

Hahahaha " Thank you in advance " - yes - that's what the little springs do - they advance the timing, or to be more correct - they steady the weighs that are advancing the timing.... And yes - the vac unit pulls the plate tight when it is in position.

[Arthurdaily]

Right, but the actual PLATE on which the points etc sits is not affected by the weights or anything is it? This is only moved backwards and forwards by the vacuum - is that bit right?

[bmcecosse]

Right.

[Arthurdaily]

Ah, with my spare (full of sand and grit) distributor I see... so the vacuum advances the points element of the timing whilst the weights move the rotor arm relative to the the points and cam?

Very interesting! And so wonderfully simple - I was going to buy an electronic distributor but this is seems so good, why bother?!

Also, just as a side note BMC , the car is running like a dream now, well dreamish anyway lol - but had a question about using a timing 'bulb'. I use the method of timing adjustment as per the MMOC video, i.e. I put the timing mark on the pulley halfway between the first and second tooth marker, then set the the distributor using a bulb between the two terminals on the coil, then when the bulb JUST lights up it's fine - then fine tune by ear advance until pinking, then retard. HOWEVER when setting just with a bulb, they say you should alter the distributor until the bulb JUST about comes on - but from which direction BMC (or anybody else), ie by retarding it until it comes on (that's what I do) or advancing it until it just comes on?

The car's running fine - just an academic question.

[bmcecosse]

Forget all about bulbs and timing lights - what setting would you use anyway??? Petrol has changed so much since the Minor was sold - any setting suggested then (40 years ago!) is not relevant now. Just run the car hard up a hill in top gear and listen for 'pinking'. If none - advance the timing slightly until there IS a little pinking - then take it back slightly so it's not quite pinking. That's the optimum setting for your engine. Best you can do !!

[les]

Advance is limited according to the number of degrees stamped on the cam base, there are differing views as to the correct cam.

[bmcecosse]

And many different cams.......it's about getting a balance between enough full revs advance -and not too much static advance...so the engine will start and idle nicely.

[les]

I've decides on a 13 degree one, seems to pick up better than 10. Wish I knew what was fitted when the 1098 left the factory.

[IslipMinor]

For the 1098 there were two ignition setups for the 'high compression' engine.

N.B. The following settings are all with the vacuum disconnected.

Distributor ref 40849B the max advance 30° to 34° crankshaft degrees at 6,400rpm, so distributor advance 15° to 17°.

Distributor ref 41124 & 41148 the the max advance was reduced to 22° to 26° crankshaft degrees at 5,500rpm and distributor 11° to 13°.

The static advance for all HC distributors is 3° BTDC.