I would be most grateful if anyone with access to the factory drawings for T37/40 valves can tell me what the specified corner radius is for the groove that the valve keepers/collets fit into.

I believe to answer your question this guys need your chassis number

Sorry, I have only access to valve drawings for the T50B and the T60 or T67...

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Good evening.
Viewing the responses you've had so far has surprised me. However, may I suggest that you contact The Bugatti Trust and ask them. They have many of the original Molsheim Drawings, quickly accessible and, in my experience, they are most helpful. If the design changed during the production run, then, as suggested already, quoting the chassis number, the engine number and, if there is one, the actual number on the cylinder block can be helpful in finding the precise Drawing applicable to your part and would be appreciated by the searcher.
Their telephone number is +44(0)1242 677 201,
Their E-mail address 'info@bugatti-trust.co.uk'
and their postal address 'The Bugatti Trust, Prescott Hill, Gotherington, Cheltenham, Gloucestershire, GL52 9RD, U.K..'
If they do have the Drawing, they will also post you a copy, at a price. Again, in my experience, they take care that it is as legible as they can make it, especially if there is a particular area or dimension that you specifically require.
Cheers.

Many thanks, Creweman. In light of the lack of response here I did go down the Bugatti Trust route, so problem solved.

Good evening. I'm pleased to hear that you got what you wanted, thanks for letting me know.
I usually try to go back to the Molsheim Drawings - you're never quite certain when measuring old original parts how much wear has taken place or whether or not they've been modified by the legions of previous owners! What is noticeable though, particularly perhaps in the case of the earlier Types, is that the Drawing is often for the individual part as manufactured. The Shop Floor Fitter would then be relied on to do any necessary tweaks to shape, drill or 'adjust' as necessary to make sure everything came together properly during the actual assembly process.
On many Brescia Drawings I've found a dimension, not as a single figure but as a range, for example 1.5 - 4.0, coupled with the note 'au montage' - loosely 'as fitted'. It certainly pays to study the Drawing carefully and thoughtfully before springing into action!
I'll welcome further comment, especially if it's constructive, on these thoughts.
Cheers,

Interesting thoughts the trust are very good as you would expect. I think one thing to bear in mind is sometimes the available drawings may not always be the final set used in production. Several factory drawings sometimes exist with different people both making parts to different factory drawings. Different drawings were probably liberated from the factory at different times.

Apologies I have no specific T40 knowledge.

You are quite right about Bugatti redrawing certain parts.Whilst Bugatti was in paris during the war his drawings were in Bordeaux.This meant that he had to reverse engineer some parts to make new drawings.One that I recall is the flip up radiator cap for the T51 etc.This was redrawn in paris in 1944.An advantage for us about this is that the later drawing is in much better condition and much more readable.The new drawing having a T73c number.In all other respects though it is the same cap.People buying a flipup cap during the 1950s would in fact be buying a T73c cap.likewise the GP steering wheel.

Good afternoon.

Altho' this comment is under the original title of 'valve specs', it should really come under the related topic of 'Bugatti drawings'. I did some delving at The Trust about 4 years ago, mainly around Front Axle and Kingpin matters, initially centred on late-Brescia details but looking to later Types for further understanding. I reached some tentative and partial conclusions as to how Molsheim operated and set them out below, hopefully to stimulate further discussion from which I can learn more.

It seems to have been Molsheim Drawing Office practice from earliest days to produce an individual Drawing for each individual Part, no matter how complex or simple that Part was - one camshaft, one Drawing; one washer, one Drawing. Very few of the earliest Molsheim Drawings have come to The Trust and it is not until the Type 22/23 era that there enough to start searching for the underlying systems of numbering and dealing with subsequent modifications to individual Parts. We are not helped in this by the fact that The Trust collection is not complete. There are however also some Parts Lists and/or Drawing Lists for particular Types which can tell us that a Drawing of a particular Part was made; in extreme cases it may only be the physical existence of a Part will suggest that it may have been - and then not necessarily by Molsheim!

By the Brescia period, Molsheim seems to have settled on dividing the complete car into a number of major Sub-Assemblies, ("Groupes") naming them and using an abbreviation of each as a prefix to the actual number allocated to the Drawing. The main ones are:-
Engine - "Moteur" - MOT
Steering -"Direction" - Dir
Front Axle - "Essieu avant" - EA
Clutch - "Embrayage" - Embr
Gearbox - "Changement de vitesses" - CV
Back axle - "Pont arriere" - PA
Chassis - "Chassis" - Ch
Shock absorbers - "Amortisseurs" - AM
Electrics - "Eclairage. Demarrage" - ED
They then applied a further prefix of the Type Number for which the Part was first designed. So you have such Drawings as "22/23 Mot 2111 - Segment de Piston", "27 Mot 203 - Soupapes" and "30 Embr 5 - Couvercle d'embrayage".

Originally the Drawings within each Type and Groupe may simply have been numbered in sequence, chronologically, as they were produced. If a particular Part was redesigned/modified for any reason, then a new Drawing Number was allocated.
All Drawings carried a 'Title Box', usually in the bottom right-hand corner, which recorded the Drawing Number and Title, the Date, Designer's initials, material to be used to make the Part and how many of the Part were required for the complete car.
There was also a short series of tick boxes to indicate the work required to complete the Part - machining, hardening, grinding etc.. A further series of boxes allowed for dates of modifications to be recorded, but curiously these seem never to have been used until at least the late 1930s onwards. Instead, an informal handwritten note was added to the Drawing in a convenient place near the Title Box. For example, Drawing Number 22/23 EA 415 carries a note "Remplacer par 22/23 EA 2334" This note, unhelpfully, carries neither the date of the change, nor of the date of the new Drawing. Around 1923/24, this practice seems to have changed to keeping the same Drawing Number, but with a new date, that of the alteration. But there is still only an informal handwritten note on the Drawing that it has been altered. An example is Drawing 29/30 EA 6, dated 25/4/1924, carries the note "Remplace le dessin du 31/7/1921" - but would there have been a Type 29/30 designation as early as 1921? However, there is a Drawing 30 EA 6 dated 30/1/25 which has the note "Remplace le dessin 30 EA 6 du 25/4/24" - not quite the same as "29/30 EA 6 du 25/4/24". The moral seems to be to check carefully for any such notes and, where possible, verify them from such other sources as you can find.

You can also come across Drawings in which the actual shape has not been altered in any way, but one or more dimensions have, usually a specific length or the diameter of a hole! Fortunately in most such cases, the original dimension has been crossed through and the new dimension applied alongside. What is not so clear is whether or not the date on such an altered Drawing is now the date the alteration was made - you need to check back to the earlier version(s) of that particular Drawing Number - if you can - to be certain.

There is more to say on this subject but I'll have to make it Part 2 - subject to any interest shown!

Cheers.

Interesting post. Looking forwared to part 2...

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Vive la Marque !!

Sadly HGC never got copies of the T251 and subsequent model drawings.You would have discovered that new nomenclature was necessary to deal with the more modern items.EG, EA [ front axle ] was replaced by TAV [ train avant ] this was used for the de Dion tube and brakes.TAR [ train arriere ] being used for the rear de Dion and rear brakes but not for the differential which remained as PA.There are several other new classifications but unfortunately I do not have a full set of T251 drawings.The general arrangement drawing for the rear de Dion with brakes is numbered 251 TAR ENS 2.I assume that the ENS is ensemble.

As far as I am aware, all of the original factory drawings are still in the hands of the Artioli family, A complete set of copies remained with the original factory and were almost thrown out. The plant manager generously decided to give all of these drawings to the Schlumpf museum, but because of this museum's innovative policy of withholding information instead divulging it, you don't have a chance in hell of gaining access to them.

Actually the drawings that Artioli is supposedly withholding were the property of the Bugatti Holding company in Luxembourg. These were the Original Molheim calques, which curiously were drawn in pencil only, which hampers the blueprinting process and hence any further copying of the blueprints. That is the reason that even some of the Trust copies are rather dark. Anyhow the Original calques that the Luxembourg Holding had obtained from Messier-Bugatti were given on loan to the Artioli cultural centre in Ora, and initially were in the care of Ivo Cecci, untill his untimely death. In the bancrupcy of the Artioli company it has been rather shady what exactly has happened to the historical collection that was held there. Since VW took over the Luxembourg Bugatti Holding company they juridically have become the owners of the Original Molsheim drawings. That is if they can find them, and if they are interested at all...

The original drawings are no longer with M.Artioli.Nor are they any longer in Italy.When and if I am allowed by the new owner to say more, I will of course do so here.He does not of course have all of the original drawings.Many were given to customers in the 1960.s by Seyfried.Also the drawings made and kept by the development department never got to the main drawing office.It is these development drawings which I have here.I have offered these originals to the new owner of the main collection in exchange for a set of photo copies of the T251/2/3 drawings which I need for my work.He has agreed but I am still waiting.I believe that all of the original drawings should be kept together.My prototype drawings have never been seen or published since 1964.My drawings include factory copies of prewar drawings which were found interesting or useful to the prototype department.IE T35 crankshaft drawings [ studied during consideration of roller bearings for the T251 crankshaft ] and T64 drawings used during conversion of the T251 from discbrakes to drums.

I understand that on purchase of the Bugatti name,VW refused the original drawings because of the one million euro pricetag.