A friend and I who have a small shop that does (mainly) vintage Rolls Royce and Bentley engine overhaul and repair have just received the engine from a Bugatti Type 44. It was removed mainly for badly leaking valves and the owner decided to have the engine disassembled to inspect and repair as required. We have nearly completed the tear-down (will be making a tool to remove the cam pins for cam removal) and have a fair idea of what needs repair and freshening up.

We have some owner provided information - articles and parts manual (French). One thing that the owner was not able to provide was a service manual or any sort of spec sheet that includes usual information such as clearances, bevel gear back lash, etc. Is such a publication available?

The main source of the valve leaks are cracks between the intake and exhaust valve seats on the inner two cylinders on both (iron) cylinder blocks. They are fairly deep and we are checking some local welding talent to see if there is a reasonable possibility that the cracked areas can be welded up, given their difficult to access location. Even if successfully welded, there is little room for valve seat inserts and I'm afraid that the weldment with a sear profile cut into it would not be particularly durable. Has anyone had experience with affecting a successful repair for such a situation? In lieu of repair, are there new manufactured cylinder blocks available for the T44?

The main and rod bearings all are visually in pretty good shape. We've yet to check the clearances, but it looks likely that they can be re-used. Some of the rod bolts seemed to have been over-torqued so we are a little concerned about re-using the rod bolts. Rod small end bushings are shot. Anyone have experience with these rods and if the rod bolts have any tendency for breakage?

There is what we feel is excessive play between the cam drive gear and the cam gear. There is no shim apparent under the drive gear. It looks like it would be possible to machine a slightly deeper seat in the cam box for the cam drive shaft bushing to locate the gear a little closer to the cam gear itself. This would be strictly a cut & try operation a couple thou' at a time to get a reasonable amount of lash, but seems like a cumbersome way to go about it. We hesitate to remove the drive coupling and at the moment there is no need as there is no excessive clearance between the cam drive shaft and it's bushing. Any knowledge on setting up lash here?

The cam and followers are scored, but repairable.

The crank has had the damper and clutch / flywheel removed and is out for magnaflux checking. I seem to remember reading somewhere in the pile of articles the owner left that they have a tendency to crack.

The clutch reveals one broken plate and a worn out pilot bearing. Otherwise in spite of having no evidence of fluid (just carbon grease muck), after cleaning it doesn't look too bad. Love the release mechanism! Very clever.

So that's about where we are at the front end of the project. Looking forward to tips, tricks and knowledge. All in all, it's a pretty impressive bit of design and engineering and a pleasant change of pace on the work bench.

Shots of the tear-down here:

https://picasaweb.google.com/n4871z/Bug ... neOverhaul

George

Nice looking shop!

It sounds like you will need new blocks, these T37 and T44 blocks were made by Brineton but are now available through http://www.gentryrestorations.co.uk/index.php. I'm sure if you give them a call Stephen or Malcolm will point you in the right direction.

What is the bike in the background?

Looking into a couple prospects for replacement cylinder blocks. Also a possible cunning plan for a repair.

The bike belongs to my friend, lead mechanic and owner of the garage, Tom Mellor. It holds the "partially streamlined / pushrod / gas / 750cc speed record at Bonneville @ 180+ MPH. He's aiming for 200 MPH this Sept. with a 1000cc motor and few splashes of "secret sauce" including the intake ducting airbox you can see.

Love the bike, my cousen is Oren Harper he runs a Harley at Bonnavile with a gang from Montana, 2 years ago he was able to set a new record for an unfaired bike

If you can affect a repair then there are litrally hundreds of old blocks in Europe awaiting your attention its somthing no one has cracked(excuse the pun). If you do buy new ones(un machined) be very carefull not all are alike and faliure rates are high as you are in Canada having a casting fail on you after investing several hours of machining will be expensive in terms of time and shipping from Europe.

hope it goes well i will look out for you on the salt;-)

there used to be a very good guy in birmingham who used to machine out the three valve seats and build up by gas welding,then remachine.This is possible,and if done well will probably be better than new.Unfortunately this sort of skill is fast disappearing in our modern world.I remember my friend Dudley Gahagen telling me that he had cracked seats in his T37.....since 40 years.He would get around to doing something about them one day but as long as the car still ran fine he didnt bother.

This engine we're told had valve & guide replacement not too long ago. There were burned exhaust & intake valves with some serious erosion from the valve seats on the cylinders where the cracks are. The main reason for removing it from the car was bad valve leakage.

It might be worth playing with the scrapped blocks to see if a cunning repair we thought of could be done. But truth is, it would be terribly time consuming and in the end not cost effective compared with a new, better material blocks methinks.

No body's chimed in about overhaul data. Nothing in the way of a compendium out there?

you need the Bugatti Overhaul Manual from the Bugatti owners club.

If you like to repair your blocks , heat them up and weld them with acetylene-oxygen .
Heat them up again and cool slowly over night . But you have to remachine the whole block . You also can slave it like in the Hisso engines .
The best new blocks you get today from Erick Koux , he is using Rapid Prototyping for the sand core .Mutch better compare to the old system . Casting and machining in Germany .
There is a German company making blocks from steel , more expensive , but no cracks .

Koux blocks are casted and machined in France, not Germany.

Proof to me that there has been one cylinder head of a high speed combustion engine made successfully from steel in the past ...

Koux told me , he stoppt casting and machining in France about quality .

" Proof to me that there has been one cylinder head of a high speed combustion engine made successfully from steel in the past ... "

Is this question a joke ?Or do you have no knowlige at all ?

Very interesting. Please tell us more about that. I assume you do not mean the production of a crankcase in steel as that is something completely different from what we are talking about here.
Bugwrench

Is this company making steel blocks by cnc-ing them, or are they cast?

I presume all blocks are cast, for their waterways (perhaps CNC-ed afterwards for finishing them). However, which type of metal do they use?

And to all: please keep this thread neat and tidy.

_________________
Vive la Marque !!

In the past , many engines had a steel crankcase , because it is stronger and lighter compare to alluminium . I think Ford made the last one in the sixties , a V6 . But Ford stoppt it , it was very light , but to expensive . Today MTU is still building steel crankcases .
Yes , I do not mean steel crakcases . In the past , it was very common to have a steel cylinder and cylinder head in one . Especially aircraft engines and racing cars . I am building steel cylinder heads for Mercedes D3a - Oberursel - Le Rhone and so on .
Have a look how a Mercedes racing car cylinder block is made .

Please give us a link. I for one would like to know more about that Mercedes racing car cylinder block but I could not find any further information. Current or historic?
Bugwrench

Mercedes racing cars have a weldet steel construktion . Cylinder and head , one part , all steel . I do not know how long Mercedes did build it this way . 1940 or 1950 .