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MG MGA - Distributor cap identification

I'm about to replace my distributor cap that has a crack on one side with hopefully one of two spares gathering dust in the garage. all caps look the same but the numbers stamped on the inside are all different - can these be used for identification? The numbers are:
5441247 (with number 17 above) -existing on car.
422904 - the Lucas name on the top is upside down compared with the others.
Are these unique part numbers or production numbers, if the latter then how does one identify a cap other than by visual comparison?
J H Cole


Are you concerned for originality reasons? I ask because if the distributor cap sits on the distributor and the wires point the right way then it doesn't really matter which one you use as long as the spark goes where it should without internal tracking.

I would guess that the numbers are just production batch numbers because regardless of the 40... number on the DM2 distributor body I think the caps are interchangeable and only differed with the HT lead exit pattern so that they presented the leads correctly for the engine lay-out.

Malcolm Eades

the original caps were marked 402944 on the inside and Made in England and LUCAS on the outside. The originals also had the bottom of the LUCAS lettering on the outside edge of the cap. The later reproduction units have LUCAS the other way up.

They are all ok regarding function, as are the other non Lucas branded units. The only thing to watch is the position of the low tension wire as there is at least one other version of this size side entry cap.

Basically I agree with Malcolm, if it fits, it's the right one!
Neil McGurk

Just to reinforce what Neil has said, the attached image is of an adapted cap supplied with my rebuilt DM2 by a well known 'professional' rebuilder company in the UK.

Needless to say I was not impressed.

Do I name and shame?


Steve Gyles

ME,Nm,SG thanks for the responses on such a specialist point. I did a trawl of the web sites and in the end found that Holden's site directly referred to the MGA cap as a 5441247 so maybe my unfortunately damaged cap is the correct one. Interestingly non of the replacement caps I found had the Lucas name on the top. Why the other caps have different numbers I do not know. From what you say however these caps are not precluded from use on the basis of 'if it fits its OK'. For the moment I'm still sticking to traditional points ignition but I'm beginning to weaken by shear dint of enthusiastic numbers but I recall Barney's comment that a properly set up system will not be improved by electronic ignition. PS checked with Bob West and the Chinese distributor is now at 58.75 -weak pound.
J H Cole

Steve, was the cap damaged or deliberately cobbled to make it fit?
JH, is it just me and you on points now?!
Lindsay Sampford


It was deliberately cut like that by the rebuilder. He was fitting their standard Ignitor electronic ignition for that distributor. I refused to pay for the cap. It was a very amateur bodge. I bought my own from another supplier and, although it had vertical lead connectors instead of side entry, it slotted straight in.

Steve Gyles

Lindsay, I'm still on points and very happy too. I also have one of those rare three synchro., four speed gearboxes; remember them?! Also dynamo, SU points fuel pump, mechanical tachometer, mechanical fan, no additional relays, no servo, "leaded" head and 6v batteries. Has always run like a dream (now that's probably the kiss of death).

I'm not an originality freak, I do have radial tyres, silicon brake fluid, V8 bushes, MGB anti-roll bar and negative earth. But if it ain't broke...!
Neil McGurk

Good one Neil and Lindsay.

We seem to be running run into this theme regardless of the topic; 5-speed gear boxes, now distributor caps.

Mine runs great also. It wasn't broke. I didn't fix it. I just modded it.

My list compared to yours: Electronic ignition, 5-speed box, alternator, facet fuel pump, electronic tachometer, still mechanical fan, no relays, no servo, unleaded head, 2 x 12 volt batteries, radial tyres, silicon fluid, V8 bushes (bet you went to Bob West), MGB roll bar and negative earth.

Plus 1800 engine, wires, discs, sports windscreen, small steering wheel, seat belts and reversing light.

Oh yes, Chinese distributor with associated cap, so not much help with John's enquiry!

Steve Gyles

LS, yup - traditional points and happy as I am at the moment. SG - impressive list but surprised no brake servo. My car is fairly original but for a servo that greatly improved the brakes. I do motorway driving and was never very happy with the old brakes especially at 70+ mph.
J H Cole

Ok to be honest I have an 1800 block too and a mild tune cam.

Steve, I think the five speed box would improve the driving experience, I have discs as it's a 1600 and it's also on wires. The V8 bushes were bought from Moss nearly 20 years ago, but only installed in 2007!

I have never been to Bob's place or bought anything from him. Next time you are popping over give me a shout and maybe I could meet you there!

One of my resto. projects will be a bit more sporty; small screen bumper-less front valence etc. That may also get a smaller steering wheel.
Neil McGurk

This thread was discussed between 20/04/2010 and 22/04/2010

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