Lucas 25D distributor question

[Arthurdaily]

Were / Are all 25D distributors identical? They all seem to have different serial numbers etc.. printed on the sides, so was just wondering - are they all the same?

As a side question, can you use a 25D as a direct replacement for an older DN2?

Thank you.

[bmcecosse]

There is a huge range of 25D dizzies...... The only internal difference is in the springs on the bob weights and the total mechanical advance which is stamped on the weight with the long nose.... And the vacuum unit fitted. And of course - different drive arrangements for different makes of car........... And yes to the second Q.

[Arthurdaily]

Lol - so one needs to get the right dizzy for a particular car? In this instance it is an Austin Cambridge MKII 1500cc - I'm presuming one would need to discuss this with a specialist then?

[autolycus]

Fifty years ago, when the cars were new, BMC and Lucas would have spent many hours on test-beds and on the road, optimising the distributor advance curve for the petrol available at the time. Who would have the resources to repeat that now?

I think it's one of those things we have to accept: we can only sensibly aim for a compromise that means the engine runs acceptably for the type of driving we do. Sure, you could look up the original spec, and overhaul the distributor till it met that spec - but would it be any better than sticking on the first reasonably unworn distributor that fits the hole? Who knows?

Kevin

[brucek]

It's been posted a few times in the past but for the newer members of the forum, here is a chart identifying which Lucas distributors were supplied for which cars. When I have a few minutes I'm going to separate the Minor info from the rest and post it here but for now you'll just have to scroll through until you find your ID number then scroll across to find out what it was originally fitted to. Guessing a few saloons will find they have a van or pick up dizzy attached

http://www.starchak.ca/tech/pdfs/lucas.pdf

[bmcecosse]

And as mentioned by 'auto' - today's petrol is so very different that the original spec won't be right now anyway........ Just use any dizzy that fits!