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Distributor

Eric990j
Posts: 44
Joined: Sun Sep 18, 2016 8:19 am
Location: Kent

Distributor

Post by Eric990j »

Hi all

I need a new diaphragm for my LD10, and ideas where to get one. I also remember that way back the club had various spares, is this still going?

I just finished a marathon 2 days sorting out the brakes and think we did it at last! Seems good on the axle stands but will have to wait till I rebuild the distributor to test on the road. Any tips
on brakes before I jack it down?

Many thanks

Eric

Marcel Renshaw
Man of Many Parts
Man of Many Parts
Posts: 673
Joined: Fri Feb 12, 2016 8:44 pm
Location: Derbyshire

Re: Distributor

Post by Marcel Renshaw »

Sorry but the club stores closed many years ago.
David Beales still advertisers in the club magazine and also has a ebay shop.
Can you please confirm you want a diaphragm for the distributor and not the petrol pump.

Eric990j
Posts: 44
Joined: Sun Sep 18, 2016 8:19 am
Location: Kent

Re: Distributor

Post by Eric990j »

Hi, definitely the distributor, it’s not holding any vacuum at all

Marcel Renshaw
Man of Many Parts
Man of Many Parts
Posts: 673
Joined: Fri Feb 12, 2016 8:44 pm
Location: Derbyshire

Re: Distributor

Post by Marcel Renshaw »

There's always the distributor doctor. You should be able to find him easily on the internet.

Simon Hyslop

Re: Distributor

Post by Simon Hyslop »

The diaphragm unit is a 419065 for 1948 on LD10s. Unfortunately, that diaphragm appears to have only been fitted to the LD10. Although the distributor type was common to a number of vehicles, the specific model for the LD10 was unique. There would seem to be two likelihoods for spare parts, either there are none or someone has a box of them they've been desperate to find a buyer for.
If the former is the case, maybe trying to have the original repaired would be a good option.
I wouldn't rule out being able to make another unit fit but the range of advance it would provide would be unlikely to match the original. However, if you've had no vacuum advance at all, some may be better than none. I don't mean this to sound negative, just that some parts were in short supply right from the start ! There's always the chance a good used one will turn up. Good luck !

Phillmore
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Posts: 847
Joined: Sat Feb 13, 2016 1:25 pm
Location: Worcestershire Herefordshire border

Re: Distributor

Post by Phillmore »

Excuse my ignorance Simon but what determines the advance? Is it the diaphragm,spring or the inlet manifold depression or a combination of the three? Are you suggesting that the LD10 diaphragm is unique? I'm not doubting your knowledge, which is beyond doubt, and your posts are always incredibly informative, but I would have thought that there must be a combination out there somewhere to restore the original ignition statistics.
Andy

1954 Conquest Mk1, 1956 Conquest Mk2, 1957 Conquest Century Mk2, 1955 Austin A90 Westminster

Simon Hyslop

Re: Distributor

Post by Simon Hyslop »

You're right , Andy, it's all three. Working forward in time, the original method of advance and retard was a lever moved by the driver. Retard to start, advance going up hills etc.
Next came centrifugal advance which is the weights and springs. That responds to the speed of the engine, more speed more advance controlled by a mixture of the weights and springs but mainly the springs. Up to the 50s there aren't really that many permutations but more complicated thereafter.
However, the part that's missing in normal driving is the need to advance when the engine is running slowly but pulling hard. That's where the vacuum advance comes in. There is a strong depression when pulling hard in the inlet manifold which transfers through a tube to the diaphragm which then pulls on the baseplate advancing the spark.
Too much advance doesn't do the big ends any good and too little won't produce maximum power throughout the range, so the range needs to be controlled. There is a mechanical stop on the moving baseplate pulled by the diaphragm but the rate of advance will be matched to the engine's needs. The vacuum advance works directly on the baseplate so if the diaphragm unit is larger or smaller in capacity, that will have an effect on the rate of advance.
You're also right, Andy, in that there should be a diaphgram that would be broadly similar to the original. What I can surmise from the Lucas parts list is that there's not an equivalent that fits with the screw on vacuum pipe. There may be a later one with a push on end but as to which one...?
The other consideration is how to make the vacuum unit fit. The LD10s unit is held on by a flange and two studs which is rather different to the 23D and 25D units which have a screwed rod going through the distributor body. It was one of 3 fixing methods used by Lucas at the time and probably the least common therefore fewer alternatives to find today.
Sorry if this is a bit of a jumble, I'm trying to control our 9 week old beagle and cocker spaniel at the same time ! By the way, please do question what I write because I hope it's generally correct but there's just so much of this to try and remember.

Norfolk Lad
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Posts: 713
Joined: Wed Feb 10, 2016 8:23 pm

Re: Distributor

Post by Norfolk Lad »

Simon yes sadly there is this part number only for the LD10 it would seem but guess that's the problem when the engine was only fitted to the LD10, got this off ebay they make vacum units but in the USA it would seem.

Many units checked for code operating specs are found defected.
Most vacuum gauges are calibrated in inches of mercury. The Mityvac vacuum pump can be use to check fairly accurate movement. 1- Check for the correct unit. Units are not interchangeable. 2 - Check the unit holds vacuum. If the unit leaks, it needs replacing. 3 - Check for proper movement. Most over looked, effecting performance, mileage and cooling. The vacuum units operates within the range indicated by the 3 digit code next to the part number. Example; the code 5 12 8 indicates, the unit starts to advance at 5 mercury "vacuum", will reach full advance at 12 mercury "vacuum", with 8 degrees total distributor ignition advance / 16 degrees spark advance at the crank. Units that no longer hold vacuum are obviously bad. It seems most people are under the impression that if the unit holds vacuum, it's considered in good operating condition. This assumption is wrong! Not obvious is a majority of original units are dry, stiff or plugged with condensed fuel vapor restricting proper movement and many operate well above the coded range. This renders the unit inoperable with very little benefit, if any at all. Replacing an original unit with a fresh new unit, often has a significant improvement in overall performance, mileage, cooling and often for much less that expensive engine modifications.

So might help a little in finding a near match unless some kind person can offer a repair service in the uk

Peter

Eric990j
Posts: 44
Joined: Sun Sep 18, 2016 8:19 am
Location: Kent

Re: Distributor

Post by Eric990j »

Ok guys, thank you. I will have a good ring round in the morning and let you know if I’m lucky.

triddell
Posts: 58
Joined: Mon Jun 27, 2016 7:08 pm

Re: Distributor

Post by triddell »

There's an owner in Wales called Catherine Jones who does youtube videos on how to do various LD10 maintenance tasks. I find them really helpful. There's one on repairing the vacuum advance, although I've not had to use it because mine works ok. If you google LD10 Catherine Jones it should come up.
Regards
Tom

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