Lucas 23D to 25D dizzy upgrade – worth it? Best brand?

[Oldmogman]

I’m considering replacing the (rebuilt) Lucas 23D dizzy on my early ex-Marina engine with a Lucas 25D with vacuum advance, which I understand gives better fuel economy and driveability.

Could anyone suggest whether it’s a worthwhile swap – will I see a big difference in fuel consumption and driveability?

If so, could anyone recommend which brand of dizzy to go for? I see a repro 25D with electronic ignition from Simonbbc is around £35, while a similar one from Accuspark is about £74.

The engine is ported and runs a 266 with an HIF44 and tubular exhaust manifold, and is to be fitted with a balanced Sprite crank and rods at some point.

[svenedin]

I would source a NOS or fully refurbished genuine Lucas distributor. These are about £100 and MMOC spares have them. Those cheap copies do not last, are poorly made and the micrometer timing adjustment does not even work (I have had one). I would say fitting a Far East copy is a downgrade. You will need to look up the correct Lucas distributor number (there are numerous variants of the 25D4) as this will have the correct advance curve for your engine. I thought though that the Marina 1300 should have a Lucas 45D4 or was that later Marinas? Btw, does your carburettor have a vacuum advance/retard pipe take off port?

Stephen

[Oldmogman]

Thanks Stephen, that sounds like good advice - I suppose that, like most things, you get what you pay for.

Given the cost of rebuilding a genuine dizzy, it does cast some doubt on the benefits of swapping my already-reconditioned unit for one with vacuum advance. I have to say that, until I read about the benefits of vacuum advance dizzies, I'd not noticed any driveability issues with my 23D, and I'm assuming any improvement in fuel consumption would be small.

And yes, you're probably right about the 45D4 - I was assuming that, with Sprite internals, my engine would be a Sprite in all but name (I think the cannister oil filter is the only difference).

[svenedin]

Thanks Stephen, that sounds like good advice - I suppose that, like most things, you get what you pay for.

Given the cost of rebuilding a genuine dizzy, it does cast some doubt on the benefits of swapping my already-reconditioned unit for one with vacuum advance. I have to say that, until I read about the benefits of vacuum advance dizzies, I'd not noticed any driveability issues with my 23D, and I'm assuming any improvement in fuel consumption would be small.

And yes, you're probably right about the 45D4 - I was assuming that, with Sprite internals, my engine would be a Sprite in all but name (I think the cannister oil filter is the only difference).

You're welcome. Yes certainly it is really expensive to have a distributor full rebuilt. I had one done by Distributor Doctor. A fantastic job Martin did but it is pricey. I have a spare distributor which was NOS from club spares and it is absolutely brand new for £100. All I have done with it is given it a clean, changed for a new O-ring seal, cleaned the (unused) points, oiled, light grease on cam and swapped for a brand new condenser (electrolytic capacitors deteriorate with age and this has been sitting in a box since 1973). I do not know much about Marinas but I think if you do a forum search you will find that some had vacuum advance and some did not due to a problem attributed to the advance that caused low end rumbling in the engine. I am not hoarding parts but as they become scarce I like to have a working spare. I have learned the hard way that new/repro parts can be highly problematic and it is worth the extra time to search out NOS or good second hand originals. Dynamos are another good example. People buy these cheap Far East C40 reproductions, they don't last and then they say all dynamos are rubbish and they must fit an alternator. If they bothered to get the genuine Lucas C40 overhauled (and there are places that still do this) they would have many, many years of faithful service.