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WW1 Thornycroft restoration


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I have just bought some 'Wynns Carburettor Cleaner' in Halfords. I hadn't thought that there might be such a thing until FlandersFlyer mentioned it a few days ago. There is always something new to learn!

 

 

 

I feel obliged to point out the if you rebuild your carbs on the kitchen table, the Carb Cleaner WILL dissolve the varnish on the table and SWMBO WILL be dismayed particularly as she had already only allowed you to rebuild said carbs in the house because it was winter AND you will immediately have to delay your restoration to refinish the kitchen table.

 

Don't ask me how I know....

 

:blush:

 

Love this restoration - am simply in awe of the ingenuity.

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It has been quite an exciting day really.. Tim and I pulled the camshaft out and rotated it through 180° yesterday. Unfortunately, he then had to go home but this morning, we were able to put the engi

We haven't balanced the shaft. The rotation depends on how well I drilled the leather so there will be some variability in it. Hopefully, there won't be a problem but if there is, then I will have to

Thanks Tomo. I'll remember that! We have had a nice day., all bright and still and not cold. I have been pressing on with the hand controls and linkage. First part was to cut the throttle shaft a

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Thanks for the warning!

 

Dad has finished painting the fuel tank and it is now ready for sealing. This has been the worst ever item for paint bubbling on the second coat due to lack of cleanliness. It seems that thinners is just not good enough where soft solder flux is concerned and we should have used scouring powder or something caustic instead. Oh well. There is another lesson learned.

 

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I have some 'Slosh' on order so once the paint has hardened off, we will try that.

 

Now back to pattern making!

 

Steve :)

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A few odds and ends going on this week. I have turned up two more carburettor choke tubes of 27 and 26mm bore so I will have something to play with when we start the engine for the first time.

 

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It was nice to meet up with several forum friends at Old Warden Steam Rally the other day. I was pleased to see that John Marshall has the same size carburettor on his Thornycroft as we have. It gives one confidence!

 

I have just bought some 'Wynns Carburettor Cleaner' in Halfords. I hadn't thought that there might be such a thing until FlandersFlyer mentioned it a few days ago. There is always something new to learn!

 

More posts shortly.

 

Steve :)

 

Wynns do many different products Steve...

 

You may need some of this for it:

 

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Steve,

 

The tank looks really Grrrrrrrrrrrreat.

 

Just a thought, considering that the paint had difficulty adhering to the outside of the tank how do you propose to clean the inside of the tank to get the 'Slosh' to stick?

What would worry me, if I was doing this, is if I couldn't adequately cover all the surfaces inside the tank would the petrol get behind the coating and start to peel it off and block the pipes or filters.

 

John

Edited by Barney
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John

 

Apologies to all as I am hijacking this thread somewhat, but I hope our intrepid Thornycroft restorers may find the contents relevant and help them decide a course of action for their petrol tank.

 

My Kettenkrad petrol tank caused me lots of grief when the rust inside started turning up as a micro fine powder in the carby. This stuff was finer than talcum powder and blew through the inline petrol filter as if the filter did not exist. The carby promptly stopped being a carby with very little warning each time this occurred. Luckily for me, both times, the vehicle was either in my shed or within a few metres of it.

 

The best solution would have been to cut the top off the tank off, get it all sandblasted, MIG welded back on then slosh it.

However, the vehicle is painted with nitro cellulose paint, which ceased to exist in Australia in the mid-1970s. The colour cannot be matched with modern paints so I was out of options.

 

I used an Aussie equivalent of PQR-15 (or whatever the US stuff is called). It comes as a 3 part system:

 

- Cleaner - industrial grade detergent.

- De-ruster - I suspect to be Phosphoric Acid or an equivalent.

- Slosh - A one pack (so no evil isocyanate health risk) silver coloured resin.

 

I don't recall which order the first 2 are used in, but you end up with what they call "flash rust"

before applying the sloshing compound. So there is some entrapment.

 

See photos:

NOTE: the transfer to the new cloud platform corrupted the layout of my photos, thus the first photo is the finished product and the last photo is just before I put the sealer/slosh in.

Description follows after combined photos.

 

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- This stuff sticks like nothing else on earth, so you need to be really careful not to get it where you would dread for it to be permanent. As I cannot get an Aussie paint to match, I protected the paint with duct tape. Wiping off spills is possible if you get to

it with seconds, but you are unlikely even then to be able to remove all indications of the spill.

 

- Using the petrol tank cap to seal the tank would have meant it would have become lagged with the slosh or at worse case scenario

permanently attached to the tank, so I made a combined bung and viewing window from the bottom of a 1kg honey container.

 

- The tank must be tumbled in all 3 dimensions to clean/treat/coat the inside, you have to keep this up for 15 to 20 minutes.

So I used a couple of buckets to make the odd shaped tank roll and my workbench as the track and also turned it end over end.

 

- What my Kettenkrad petrol tank looked like after the first 2 applications and before the sloshing compound. This photo is looking up towards the filler opening (taken by holding phone in 2 fingers down through filler opening). Top is to photo right, bottom is to left in photo.

 

- Same location after sloshing. I am not entirely happy with coverage as it looks a bit thin at top of baffle. But a huge improvement on what I had. The slosh is humidity activated, knowing what I now know, taking the dry desert climate of Broken Hill into account

I would ignore the warning in the instructions to drain the slosh by 20 minutes maximum as it was slow to cure. In the wet British climate I would be following the instructions.

 

Note: to Gosling clan, I too would be concerned about the effect of your soldering flux and would be making sure I had a way to

dissolve and clean it out before undertaking the sloshing system.

 

Regards

Doug

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Edited by dgrev
spelling and layout correction. note regarding cloud update causing photos to be out of sequence!
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  • 3 weeks later...

Hi Chaps.

 

Many thanks for all of the advice and guidance. All very useful and interesting. I was in Devon for the weekend so we have finally bitten the bullet and lined the tank. I bought two tins of 'Slosh' for a total of £60- delivered. (Ouch!) and, as the tank has never held fuel we poured it in and tumbled it for an hour.

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It was a most soul destroying job as we couldn't see what was going on whilst trying to handle a most awkward shaped tank without scratching the paint. Eventually, we poured out the remainder and ended up with about £40- worth to dispose of! Oh well. The job is done nowand the tank is hardening off ready for when we can all get together and fit it. I will be pleased to see it installed!

On a more interesting front, I cut a gasket for the carburettor and then fitted it to the manifold.

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It looks quite nice so hopefully, I won't have to touch it again. We shall see!

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More to post later but I need to get the hang of the new website!

Steve :)

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10 minutes ago, Old Bill said:

It was a most soul destroying job as we couldn't see what was going on whilst trying to handle a most awkward shaped tank without scratching the paint. Eventually, we poured out the remainder and ended up with about £40- worth to dispose of! Oh well. The job is done nowand the tank is hardening off ready for when we can all get together and fit it. I will be pleased to see it installed!

 

Steve. The wastage is indeed annoying, but because you cannot see whether 100% coverage is happening erring, on the side of excess is the only way to try and ensure everything is indeed covered. As you will have discovered once it it time to pour out the excess it is on the way to setting and it would not be advisable to try and do another tank. Perhaps sacrificing a paint brush and getting in 10 minutes of painting something exposed to the weather and that would look ok in metallic silver would be a way of using some of the surplus. However chances are high you would come to a sudden halt and when everything had hardened have to cut the paint brush off whatever it had become a part of.

Regards

Doug

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Thanks Doug, If I had thought it through a bit more, I could have lined my two-gallon tins at the same time! Some of them are getting a bit tired. Oh well. Will have to do that next time.

 

Dad has also been pushing on with the silencer. He first cleaned up the silencer ends which, with very little work, fitted the tube nicely. Thanks to Barry's excellent pattern making! He drilled the centre hole for the tie bar and three holes inside to support the baffle rods. Finally, he bored out the ends to accept the exhaust pipe itself.

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We then went on to assembling the baffles. These are threaded onto three rods and located in our case by split pins. I am not quite sure how they might have done this originally as I have no drawings and only a picture of a baffle in the parts book. I suspect that they may have been crimped. We may find all of the baffles at one end one day!

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Then it was 'spot the deliberate mistake' time. How do you slide four circular discs down a tube which has a row of rivets  down its length? Dad notched all of the discs with a file and that did the trick. I don't know how Thornycrofts did it though!

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Ready to fit!

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Now we need some mounting brackets. Father had picked up the bracket castings a while back and cleaned them up nicely.

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I then finished them off by adding the mounting holes.

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In the meantime, Father had rolled up the mounting bands and fabricated the end fittings.

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After a rummage for some rivetes, we found just enough and put them together.

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After cutting to length and drilling, the rivet holes were counter sunk.

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We knocked up a snap from a piece of bar with a dimple created with the end of a drill. Not a perfect shape but good enough for this exercise.

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Then it was simply a case of knocking them down.

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The results were quite pleasing so they are now in the paint shop.

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I am working on the rest of the exhaust at the moment. We need a flange to bolt it to the manifold and a cast elbow. We do have a very sad original but I think it can be saved with a little help from my friends again but that will be a story for another day.

Steve     :)

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If we are going to do the body over Christmas, we are going to need the body mounts. These take the form of six castings bolted to the chassis rails which hold three of the cross-members. There are two sorts (why didn't they use just one?) of which one supports the end crossmembers and the other the centre one.

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The intermediate type of which, for some reason, we don't have a decent picture.

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Fortunately, I made enough sketches so I started the job with the usual pieces of MDF.

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Which were then glued up.

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The end castings have an arch which require a core to create them. This block is for the core print. It is on my trusty cross-cut saw which is a great boon to cutting straight!

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The core print block going into place.

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A bit of filler for the fillets.

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After an hour's dressing off with the Dremel and abrasive paper.

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Similarly for the end mounts.

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All dressed back and ready for some paint along with the core box itself.

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All painted with the usual two coats of Bondaprime and polished with wire wool.

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Those are pattern numbers twenty three and twenty four. Only six more left to do!

Steve    :)

 

 

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Wouldn't you want some radius on the core to avoid sharp corners inside the square hole? It ought to be fairly easy to work in on at least 2 edges. 

I assume the moulder will have to dig down to the pattern? Making a follow board might be friendly. 

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I didn't want to put radii on the core print as they might tend to keep the core up if the radii there did not match. I could have added radii to the ends of the core but the longitudinal edges would be tricky. As we only want four off, I will let the moulder just scrape the edges if he sees fit.

Not quite sure what you mean with the 'follow board'. I anticipate the moulder placing the pattern on its back and packing around before turning it over and drawing it straight out. The core should then just drop in, if I have my clearances right!

Dad has already taken them to the foundry so we should see the results in about a fortnight.

Steve     :) 

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1 hour ago, Old Bill said:

Not quite sure what you mean with the 'follow board'. I anticipate the moulder placing the pattern on its back and packing around before turning it over and drawing it straight out. The core should then just drop in, if I have my clearances right!

I might have the wrong impression of the shape. I have only seen it in 2D here as pixels, not 3D in wood. I didn't think that there was a flat face with non re-entrant sides. I might, just possibly, be wrong in this. :-)

 

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Eh, I am a bit confused as well. Will they use the 'pencil box' shaped piece to make a rectangular sand core, then use the big pattern to make the main cavity, and then insert the rectangular sand core into that cavity. But does that not then leave a cavity the length and width of the rectangular sand core above it, which presumably you plan to machine off as required later? Or have I not only got hold of the wrong end of the stick, but the wrong stick completely...?

trevor

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If the piece in the middle of the photo was laid on its back (same orientation as the piece on the right) for ramming up, then it will leave the core print exposed at the bottom. The core goes in, then leaving a space behind for the part, and the other half of the mould is just flat sand. Right?

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I think I can see where you are going! If you look at the very first photo of the original casting, you will see that the rear face is flat so the pattern is laid on that face for the first box to be rammed up. The core is the shape of the square hole plus a bit each end to support it so when the box is turned over and the pattern drawn, there is a squarish recess either side into which the core drops. You are right, the metal does go above the core to form the back plate of the casting. Hopefully, the core won't float off in the molten metal as that would spoil the job.

At least, that is the theory. If it doesn't work, no doubt the foundry will send it back!

Steve    :)

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There is no reason that the casting cannot be cast with its flat back face down. That way the core cannot float away. Alternatively the core could have been made an inch longer at each end so that it is fully retained in the mould.

Looking again at the photos of the original castings I am wondering if they all originally had the box shape, but that the two without the 'box' had either been deliberately or accidently modified, maybe by over tightening the through bolt ?

David

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The two mounts are definitely different as there are two part numbers for them in the parts book. I am still cursing though as if they had been the same, I need only have made one pattern!

We have been thinking further about the cooling system as sooner or later we are going to want to run the engine. On looking at the Carlton Colville lorry, it can be seen that the outlet from the radiator is an aluminium casting leading into a copper and brass fabricated elbow.

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The fabrication is original and is shown in the parts book. However, I could not see how I was going to bend a piece of two inch pipe. Fortunately, the Americans use 2" copper pipe in their household water systems and I was able to buy an elbow which I think will do the job. Whilst waiting for that to arrive, I made up the flange from a bar end of brass which Dad had on the shelf.

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It quickly became clear, however, that I wouldn't be able to finish it until the cast lower elbow was fitted so that I could set the angle and cut the tube to length.

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Rather oddly, the elbow is an aluminiul casting in the shape of a ball with a spigot on the side. Goodness knows why Thornycrofts did that but it didn't make it any easier! The only piece of wood I had big enough to do the job was a piece of 3 1/2" oak. I put it through my bandsaw which was decidedly cruel to it.

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Now, a chance to use my new toy! One of our regular readers has very kindly presented me with a wood turning lathe. Time to learn some new skills!

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I think I need to invest in a dust extractor.....

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I did achieve a result though.

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A qick turning of the spigot and core prints on the trusty Myford (the only way I can turn straight at the moment!) and the cutting out of the flange and I had a kit of parts.

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I glued the spigot on but left the backplate loose so that I could set the angle to align with the fabricated elbow.

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Looking good!

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The flange was then secured in the final position.

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In the mean time, the core box was beckoning. First step was to glue up some blocks.

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Then drill the main ways.

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Tidy the ends out with a gouge,

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One core box,

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By this time, the main pattern had gone off so the next move was to saw it in half.DSCN6943.JPG.3b355ad967520b893735ddb5b9ca1770.JPG

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I had lost some thickness due to the saw cut so I made this up with some 1/32" ply glued on to each face. It has the added bonus of giving a nice flat surface as well.

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A bit of filler in the corners.

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Dressed out with the Dremel and glass paper.

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Pattern number 25!

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Just five more to go!

Steve  :)

 

 

Edited by Old Bill
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  • 2 weeks later...

As a slight aside, I have been pushing on with the exhaust system. We are fortunate to have part of the original downpipe and elbow, albeit, a bit poorly.

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For some peculiar reason, Thornycrofts made this elbow, like the water elbow, in the shape of a ball which strikes me as very odd. It certainly doesn't make pattern making any easier! Fortunately, we have an original although the mounting lug is snapped off.

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Adrian kindly sandblasted the joints for me so that I could see how they were made. We came to the conclusion that the pipes were just pushed in so removing them should be easy....

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I started by cutting off the remains of a non-standard flange which was rusted beyond salvage.

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Then I split the first tube up the middle using the dremel and some grinding wheels. After some persistence with a cold chisel, it began to move and eventually came free.

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The other end was a lot harder to shift as it was slightly longer so that it protruded inside the ball and corroded on the outside jamming it in the hole. However, persistence was rewarded and out it came.

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I attacked the remains of the lug with a file.

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And then, after reference to the parts book to see what shape it should be, I cut a new one out of cast iron. I have chamfered the edges and that is now ready to weld on. I shall be seeking another favour very shortly bearing in mind that I can't even weld black mild steel!

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Steve  :)

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1 hour ago, Old Bill said:

And then, after reference to the parts book to see what shape it should be, I cut a new one out of cast iron. I have chamfered the edges and that is now ready to weld on. I shall be seeking another favour very shortly bearing in mind that I can't even weld black mild steel!

I think this is somewhere where silver solder would be the right choice, unless you think it will get hot enough to melt it. 

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Maybe that downpipe was a tuned length, venting into a 'large' space. The fact that the downpipe extended into the ball while the exit pipe did not could be an attempt to ensure the required tuned length, discourage reverse flows and encourage the gas to escape. It may even have had some silencing qualities, but it is all delightfully mysterious.

trevor

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1 minute ago, GeePig said:

Maybe that downpipe was a tuned length, venting into a 'large' space. The fact that the downpipe extended into the ball while the exit pipe did not could be an attempt to ensure the required tuned length, discourage reverse flows and encourage the gas to escape. It may even have had some silencing qualities, but it is all delightfully mysterious.

trevor

Trevor

I know that tuned pipes can be essential for certain 2 stroke engines, without them, they just won't produce power.

But I have never heard of a 4 stroke that needed "tuned" pipes in the sense you are thinking.. The advent of what is now popularly called "extractors" came about in the aero world trying to extract every last once of power from large radial engines. Basically, the outflow from the preceding firing acting as a venturi like effect.

The most noticeable use was on the engines in the Caribou transport plane and caused the distinctive crackle of those engines.

Have a look at any photo of a Merlin or Allison and you will see that the opposite was the norm, as short as possible exhaust pipes: as it turned out, in the mistaken belief that the least resistance to exhaust flow was the most efficient design.

I suspect, but will stand corrected, that the technology in use in WW1 due to the very basic designs  and poor efficiencies did not extend to such exotica.

As to the actual reason for this design, I have not a clue.

Regards

Doug 

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Hi Doug, it is indeed from an era where such things were still in development, and it would be interesting to find a paper from that time that gave us some idea. There may even be a patent for it out there.

Four strokes still respond to pipe length, though, which is why on performance cars the exhaust manifold often looks like a bowl of spaghetti in an attempt to fit in a set of primaries of the right, equal length. I just wish I still had access to a dyno to try out this ball design.

Trevor

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