Morris Minor Owners Club

Time to think about replacing c.b. points and condenser, thinking this would be easier on the workbench,
are there any pitfalls to watch out for when removing the unit or just unbolt and pull out ?

Only screwing with the set up of the timing.
Seems a lot of effort to go to just to have it on a bench
Whatever floats your boat as the saying goes, but I can think of no advantage gained.

Bending and stooping harder as you get older ! just trying to make the task easier.

Just don't loosen the dizzy clamp bolt or turn the engine at all while the dizzy is out and it should all be fine....

It would be easier yes and you could give it a proper clean and service. As long as you don't slacken off the clamp bolt (the bolts you want to undo are the two 7/16" AF securing the distributor to the engine).

Good advice MOJ and JJ , I will be careful with the adjustment, no danger of anything dropping off into the works then ?

No not really, the main thing is catching the 7/16 bolts and washers (I put them back in the holes after removing the dizzy so I don't lose them). The fiddly bit is when you change the CB points with the little nuts, washers and screws, but you might have a 'one piece' quick fit contact set. But all that will be a lot easier with the dizzy out as you said.

Oh yeah, I forgot to say, keep the old ones in the car as 'known good' spares.

Why undo/remove the two 7/16" UNF bolts?
To remove the distributer just slacken the clamp bolt and withdraw the distributer.

Yes, if you are confident and experienced, but otherwise, if you don't release the clamp bolts and instead release the two 7/16" bolts as mentioned, and don't turn the engine over at all before replacement, you can't lose the timing. One less thing to worry about!

myoldjalopy wrote: ↑Wed Mar 24, 2021 9:48 am Yes, if you are confident and experienced, but otherwise, if you don't release the clamp bolts and instead release the two 7/16" bolts as mentioned, and don't turn the engine over at all before replacement, you can't lose the timing. One less thing to worry about!

Mark the dizzy body and the clamp with tipped, paint or an indelible felt tip and you can then put it back in the same place. Just be careful that you don't rub the marks off, could also scribe some alignment marks on.

This talk of retaining the timing is actually a bit misleading. Unless the points gap, after changing the points is exactly the same as before, the timing will change. Perhaps not a lot, but away from ideal.

The engine should still be retimed after changing the points as the points opening may occur at a slightly different point on the cam.

Two separate things there:-

1. The points gap/dwell angle.
To set the dwell angle a dwell meter should be used. The dwell angle is 60 degrees. Much more accurate than setting the gap with a feeler gauge. Setting the dwell angle will compensates for any wear to the distributer cam and bearings.

2. The ignition timing - the point at which the spark occurs.
To set the ignition timing a timing light should be used. Not all 'A' Series engines benefit from utilising the factory setting and may require a slightly different setting. The factory setting is a good base line from which to start.

oliver90owner wrote: ↑Sun Mar 28, 2021 7:56 am This talk of retaining the timing is actually a bit misleading. Unless the points gap, after changing the points is exactly the same as before, the timing will change. Perhaps not a lot, but away from ideal.

The engine should still be retimed after changing the points as the points opening may occur at a slightly different point on the cam.

Yes, I was thinking of past experience with other engines and getting the Dissy back in the same place 'Spline wise', I was forgetting that the Minor Dissy has the offset pin rather than meshing straight to the splines. I've had bad experience in the past with Dissy's being a spline out.....

Why would you need to check ignition timing after a routine CB points change? Who on Earth even does that? The whole idea of removing the distributor complete with clamp is to retain the ignition timing settings. There would be absolutely no need to adjust the ignition timing. Lucas gave the points gap as 0.014" - 0.016" so were not concerned about 2 thou, so unless you were well out of this figure (which would be a fault in itself) it isn't going to matter. It just confuses the issue.

Exactly so JJ. I've never known any owner or mechanic check the timing after a routine points adjust/replacement. It would be a waste of time.

The point opening has absolutely nothing to do with the timing. It is merely the recommended opening to maintain a suitable dwell angle and not burn the points (by sparking, which would occur with a too small opening or by the points opening too slowly, with the same result). It is a function of cam design along with the Kettering ignition requirements.

Anyone with any engineering knowledge would understand that as the points wear, the points gap will reduce (due to heel wear) and so will retard the timing by a small amount between service intervals. It is why the gap should be checked periodically. Engine power, efficiency and longevity rely on parameters being maintained close to optimum.

The points could be opened, by the cam, at a much later point (to increase the dwell angle) but the rate of opening would clearly increase the wear on distributor cam and contact set heel. It is all a compromise to increase contact life, reduce mechanical wear and satisfactory ignition operation. Indeed, magneto systems tend to specify as little as 12 thou separation and Ford recommended a 20 thou gap. The timing is set at whatever the points separation exists.

Further, the contact points should be parallel and completely flat. Unfortunately some are not as parallel as they could be and burning of the points (in service) results in erosion from one contact and deposition on the other, making feeler gauge setting possibly somewhat less than accurate, particularly for those without that knowledge.

Non-contact switches (generally Hall effect devices), of course, do not have this wear problem (just for those without much engineering knowledge).

New points would put things back to the default settings, whatever they were.

Yes and that's the point, Les. If everything is set up properly in the beginning then, as long as you periodically check and adjust the contact breaker gap correctly, all settings are maintained. I haven't touched the timing for over 12 years now, but I have cleaned/adjusted/replaced points in that time and the car continues to run lovely.