Hi,

I'm looking for all kind of technical information concerning the T57, mainly the engine.
There should exist more than only the T57 handbook or the few drawings in the Bugatti Magnum book.
Maybe something like a workshop manual exists where I could see the engine internal details.
There was apparently a book by Hugh Conway about T57 restoration but I have never seen one also I don't know how complete it is.
I would be very happy if someone can help me out on this.
By the way, has anybody in here already replaced leaking spark plug cups?
Is that feasible without removing the engine or even the block?
It seems to be a common problem as sometimes I see oversized cups on engine pictures that seem to cover the leak area.

Greetings:

minime

my experience, this manuals are worthless . What kind of info can you use ? What info you are looking for ? To pull the spark plug cup out , weld something to the inside , and pull it out . Make a new one with a groove for a puller . Use a modern o-ring .

It would be sensible to repeat here that it is safer to machine out the old plug cups.Certainly not a job to do with the engine in situ.Welding to an old cup and pulling to remove the old cup can remove a large part of the block down to the combustion chamber.Better to forget removal,and press in a stainless steel repair cup inside the old one.There was, famously,a stainless steel egg cup which fitted perfectly ! Silicon sealing an old block is also a useful job to do if the block is removed for any reason.This can stop small cracks from becoming a problem before they start.

Hello Udo,

Thanks for the advice.
Have you already done such works with the engine in place?
An O ring for the upper groove is for sure the right thing but how would you proceed with the lower seal?
The engine still has it's 18mm plugs.
I could make cups with an 18mm plug thread at the lower end and try to get it sealed in that area either with an additional O ring, a seal or even some 2 component Loctite that at least on some of our test engines worked fine to seal Kistler pressure transducer adaptor tubes in aluminum cylinder heads.
I that case I would have to screw the cup into the existing spark plug hole using modern plugs after this.
The other method would be to buy or make new cups as they were original and then either press or if the force is not too excessive for the spark plug threat pull in with a puller that I screw into the spark plug hole.
I have never done this and I have no idea what force is needed.
The actual leak is really small and for the moment there is no imminent need to touch it . A few days ago I have seen a T57 where the water already is running down to the workshop floor and the owner considers to use radiator seal additive to cure this what will most probably not fix the leak but clog the radiator.

Greetings:

Minime

Hi,

Yes,

I'm not too keen on welding something to the old cup either as long as the engine is still in the car.
On the other hand if the engine is out it wouldn't be a problem to get the cups machined out on a mill.
As the leak is very small I was looking for something that could be done without removing the engine.
Some Bugatti experts in the UK (I hope this will not launch another discussion on British engineering expertise) told me not to touch them and to use sealant product....
Do you know if and where those stanless steel egg cups or a drawing of them is available?
I suppose that they must have an O ring in the upper region that covers from outside the leaking original cup.

Greetings:

Minime

With modern Locktite products the sealing rings can probably be left off.

if you weld all the way around inside the cup , the cup shrinks if it cools down .Heat up the bottom part , and you can take the cup off . Use the spark plug hole to help getting it out .

I think that using the spark plug hole will not work as the spark plug threat is one piece with the combustion chamber but not with the cup.
Also the original cups don't have a threat for the plug but seem to fit somehow around the spark plug hole dome on the combustion chamber.

Minime

missunderstanding .
the spark plug threat is one piece with the combustion camber . This is why you can use it . Need a drawing ?

The T57 cylinderhead plug boss area is too fragile to take a chance on breaking it off.It is STRONGLY advised not to try to remove the cap by pushing against the plug boss.

after welding ( not gas welding ) inside the cup , you can take it off easy .

Ok,

I understood now how to remove them but how about re-installing new ones.
Do you think that they can be pulled in by screwing a threat bolt into the spark plug hole?
Still I think that turning new cup inserts that would fit over the existing ones might be the better solution for a not disassembled engine.

Minime

I do not really pull them in . I use top and bottom a modern o-ring and you can press them in with very little force . On top , inside a small edge , and you can pull them out easily any time .

I have owned four T57 cylinder blocks, every one of which had damaged cylinderheads where people had tried to remove the plug cups.A repair cup loosely fitted inside the original with a modern Locktite is the safest way to sort out this problem.

I do support Lazarus here. The Udo method has a guaranteed 50% failure rate. Never ever try to pull the old cup out but machine it out. There is a very useful T57 workshop manual available form the BOC that describes three different methods for repairing these leaks. Although this manual has been written a long time ago it still contains a lot of good general information about the T57 engine.
Do follow the suggestion of Lazarus if you have only one minor leak and you are reluctant to disassemble of the engine.
Bugwrench