Distributor servicing

[Davey]

Hi all, Ruby Morris is much happier with that new diff, 1:4.55 is a good fit for the 948cc engine and box!

Hills are terribly sluggish though. On the flat I can cruise comfortably at 45 and 50 isn't too tough, but even relatively shallow hills (bear in mind I'm in North Devon!) get me down to 10 or 15 mph.

The engine isn't in a good state, but I thought I'd have a look at the distributor to see if the advance retard was working. On the car, I found that if I sucked on the vacuum inlet I couldn't move the contact plate at all, but I could nudge the plate just a little with a screw driver.

Tonight I decided to take the dizzy out and have a look. It's marked 754BN214 and then 40299J - which I think is the model number. I can't find reference to a 'J' suffix version at all so I'm not sure if it's right for the car (a 1954 cheese grater SII with its 803 engine and box replaced with 948cc ones).

I think it's an early DM2 as the contact plate is held by 2 screws and the vacuum arm is held by a little pin and a clip, rather than a spring.

I found that when the vacuum unit was removed from the distributor, with all the sucking I could do I could just about move the arm on the vacuum unit a little. Moving the arm resulted in the diaphram puffing, but although I've never examined one of these before, I suspect it should have much more movement, and that movement should be easier.

Onto the distributor, I took out the points and condenser and had a look at the contact plate, which rotates with a little effort, but a few degrees in either direction and it sticks (I think when something on the bottom edge of the plate runs off it's 'track', then I have to lever it up a little to return. I think it should move much freer. Looking at my manuals I think the plate should just lift out? Mine wouldn't budge - it felt like it was held in the middle and if I levered it gently at the edges it just pivoted at the middle and then settled back down.

Does anyone have any removal tips, or should I be brave and just use screwdrivers to lever it at opposite edges together? I want to strip it off so I can clean and lubricate, as well as check the weights.

While I suspect I'll need a new vacuum unit, I'm rather hoping a little care will get the contact plate moving freely.

Any thoughts and ideas would be gratefully received!

Thanks very much, davey and Ruby

[Declan_Burns]

Davey,
If you want to be sure your distributor is set up properly you should consider sending it to Martin Jay-the "Distributor doctor" for “Reconstructive Surgery”.
Not cheap but he does excellent work.
http://www.distributordoctor.com/

Regards
Declan

[RobThomas]

Check that the screw holding the condenser to the plate isn't too long and restricting the movement of the rotating plate. If a washer is missing it can touch the base plate below and you'll get no advance. BTDT.

The 40299 IS a DM2 for the 803. If it has that pin then it is an early one.

40299A DM2P4 CW 504 3000rpm@18degrees advance, 1500@9.5, 550@1.5 MORRIS 4 cyl, 1952-56 superceeded by 40494

Vacuum module... 40299 419832 3 13 12 Hex pin , meaning that it starts working at 3 inches of mercury, all the way up to 13 inches and will give a max of 12 degrees of advance by the time it reaches max vacuum.

The 'J' means that it is a small variation from the standard 'A' version that doesn't affect the advance curve, such as a changed screw thread, paint finish, rubber seal or that kinda thing, if you see what I mean. Any advance curve change would give a different main 5-digit number.

[Davey]

Thanks Declan, thanks Rob!

Declan, I'm quite close to the distributor doc, and I might well give him a try... but I do like to fix things myself if I can .

Rob, that's amazing info. I'd done some homework and you've confirmed what I'd learned and expanded it massively I did have the condensor out so it's not that screw, but a good shout all the same.

Once the contact set and condensor are out, should the plate lift out or are there any other fastenings? It's not wanting to come free and I don't want to force it if there's an extra fixing or two. My manuals suggest it should lift out.

Ta very much, davey.

[kennatt]

whilst I appreciate that you are keen to re furb your old dizzy,and that's an admirable trait,Is it not easier to find a known good s/h and fit that to see if it cures your lack of power on hills. Then do the rebuild ' I'm not too sure that what you are doing will improve your hill climbing to any great extent ,have you had a compression check done ,that would give you a better indication of the state of the unit as a whole. But good luck anyway/

[Davey]

Thanks Kennatt, I do agree actually. Alas funds are tight so I have to make do and mend whenever possible.

My plan is to take the dizzy out when I have a little more time (and daylight), and service it as well as I'm able. IF that gets the advance retard moving smoothly and I find everything else to be in reasonable condition, then I'll look at getting a new vacuum unit for it. If not, I'll look at replacement or professional refurb.

Also agree on the compression check. However, it sounds like the mains (or some other bearings deep down low in the engine) are at the end of their life so I don't want to spend out on testing a unit that's had it anyway. I'm expecting to have to replace / get it reconditioned eventually. My little car does low mileage so I'm hoping it'll last out a year or two.

So, I'm not expecting miracles from a repaired dizzy, I don't think things are going to run well until the engine's fully sorted. But it's a job that needs doing, and any help my little car can get will make her happy

Thanks very much for the input, it really is greatly appreciated!