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SimonBrown

8 Cylinder Torpedo Engine - Restoration

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Simon,

I have made the blank for the special tool.  Unfortunately, my smallest dia end mill is 3/16 and it takes out too much material, ie the other teeth.  I have got a smaller end mill on order.  It will not take long to make the tool when I get it.

It would be possible to make a tool to clean up the threads.  I should be able to do it but neither of my two lathes has a working thread cutting facility and so I cannot offer to make such a tool.

John

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1 minute ago, attleej said:

I have made the blank for the special tool.  Unfortunately, my smallest dia end mill is 3/16 and it takes out too much material, ie the other teeth.  I have got a smaller end mill on order.  It will not take long to make the tool when I get it.

John - that is brilliant - thank you so much. There really is no rush on this one, the project reminding me of patience in this instant-gratification world.

 

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More time to tinker with the engine. A new tool arrived so the cylinder head plugs were tackled.

6 of the 8 cracked and undone. Two have not, refused to budge even with heat on them and the 1/4" square drive started to give. Looking at some of them, it looks like I'm not the first to have a go at undoing them.

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Above; the plug is out and on this cylinder the piston is about as close to TDC as it gets. There is very little clearance.

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Now in typical torpedo fashion the thread on the plugs is non-standard - or at least as far as I can tell:

O.D. 0.545"

18 TPI

And that matches nothing in my Zeus data charts...

Anyone recognise it?

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Nearest I can think of is 1/2" 18 tpi  uns (unified special) used for special purposes 

is it a tapper thread or is it a flanged plug?

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Hi

Being a pipe thread, probably 1/4 " NPT

Cheers Richard

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12 hours ago, hummermark said:

Nearest I can think of is 1/2" 18 tpi  uns (unified special) used for special purposes 

is it a tapper thread or is it a flanged plug?

It looks to be a parallel thread with a machined face on the underside of the small flange.

Thanks for the suggestion -  will have another look with that thread in mind.

 

12 hours ago, 64EK26 said:

Being a pipe thread, probably 1/4 " NPT

I tried a 1/4" BSP thread (had a fitting lying around) and whilst it wound in, it was like throwing a sausage up Cumberland High Street (slack) as they say. 

The 55 degree thread gauge fitted near perfect snugly on 18tpi, so maybe not NPT?

Edited by SimonBrown

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This table maybe definitive on thread sizes:- 

http://pages.cs.wisc.edu/~bolo/workshop/thread.html

As the 1/4" BSP thread is too small, could it be Whitworth pipe thread?

From the table, both are 19 TPI

BSP dia. 0.518"

Whitworth pipe thread dia. 0.5313"

Another thread that is close is the Admiralty:-

9/16" - dia. 0.5556 - 20 TPI

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43 minutes ago, MatchFuzee said:

This table maybe definitive on thread sizes:- 

http://pages.cs.wisc.edu/~bolo/workshop/thread.html

Another thread that is close is the Admiralty:-

9/16" - dia. 0.5556 - 20 TPI

I did offer up a 19 TPI thread gauge and it was close but there was daylight, whereas the 20 TPI was spot on.

The Admiralty thread looks absolutely spot on. I'm going to measure the OD of all 6 of the plugs and see. I'm using a vernier calliper, not a mic, so it will be near enough I think.

And having measured the sample, I think we have a match. All are within 4~6 thou of the stated OD - many thanks MachFuzee, its a thread I had never heard of before.

Edited by SimonBrown

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23 minutes ago, radiomike7 said:

Admiralty seems to be a 55 degree, same as Whitworth, can you measure the angle?  

The Whitworth thread gauge is a very, very close match certainly on the TPI and thread angle. Just a hint of daylight - pinprick no more - on the root of the thread.

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6 hours ago, SimonBrown said:

The Whitworth thread gauge is a very, very close match certainly on the TPI and thread angle. Just a hint of daylight - pinprick no more - on the root of the thread.

Credit to MatchFuzee, I was not aware of Admiralty threads. 

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Simon,

I have made the tool and posted it to you.  It should arrive tomorrow (hopefully).  Pics of tool are below. The reduced size on the end of the lever handle is to accommodate a 3/4 drive extension.

John

TORPEDO 1.jpg

TORPEDO 2.jpg

TORPEDO 3.jpg

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The tool arrived in the post this morning. The inlet valve caps had been soaking in penetrating oil for a few days now, but of all the fasteners on the engine these gave me the most concern. They were as tight AF and were completely bespoke and unique. These really needed to come apart with as little grief as possible.

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The tool fitted a treat. No fettling required and no slack.

An extension bar was needed, but 7 of the 8 made that satisfying crack as they undone. The last one needed a little heat, but soon gave up resistance.

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All 8 are now undone. Typically, all valves carry the '113' engine number and a single digit indicating what cylinder they relate to.

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The cap in the image above didn't come from No. 6 pot - its stamped '2' and just happened to be lying on the cylinder!

A really big 'thank you' to John for his skill, time and effort making up and sending the tool. Much appreciated as the caps have remained unscathed or damaged in any way.

Next step will be unbolting the cylinder heads. I think a 5/16 Whitworth crows foot spanner has been located.

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A big thank you not just to John, but to you too Simon for what you are doing. To we observers it is a revelation and an absolute treat to see what can be done  with the right attitude and a lot of skill.

Keep up the brilliant work, I am in awe.

Steve.

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Posted (edited)

The engine has taken a back seat for a bit. Mainly while I progress a couple of underwater projects, one of which is scanning an entire 52 acre lake in 3D. I will share the model here, if only for the tenuous link that there is the hulk of an AFV432 sitting in 24m of water:

Section of quarry with AFV432

But with that processed and out of the way it was time to crack on with the engine. First up, the tappet rollers from all even numbered cylinders were pulled out. This proved to be the easiest job of the day:SBrown-20190310-0002.jpg.6eb9152baa0f46e1179646221e681e92.jpg

Then it was time to get the cylinder bolts undone. After slimming down a ring spanner to wafer thin, the nuts were removed. Space was a premium:

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Now the it appears that the cylinder heads are held down with studs. Not so. Of the 12 fixings, 8 are pan head screws:

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And when viewed from inside the crank case:

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There is two visible in the above image, very close to the cylinders. Now, true to form several of them started to rotate with the nyloc nut. This proved to be a PITA and needed another special tool knocked up on the bench grinder and careful filing:

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Its a knackered 1/2" allen key I have had lying around in the toolbox for about 30 years. Kept for no good reason apart from "It will come in handy one day". And so it did. Not easy to access, but eventually they all yielded and bingo, the first cylinder slid off the crankcase:

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Now its pretty mucky inside, but in excellent condition with remnants of preserving oil oozing from every pore. The purpose of the oil pipes that were running into crankcase next to every cylinder is now understood; its injecting lubricant directly into the bore and presumably finding its way down to the big end.

After initial success the predictable happened and the worlds thinnest ring spanner split when attempting the next cylinder. A crows foot spanner is on its way and progress should return.

The gudgeon pin appeared to be held in place by a split pin, but on closer inspection there appears to be no gudgeon pin at all - not in the traditional sense at least - and after the split pin was removed closer inspection has left me wondering how this assembly goes together, and apart. I will post up some pictures soon.

 

Edited by SimonBrown
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Yesterday's foul weather meant other outdoor stuff could wait. So what better than to get a brew,  put the radio on a progress the engine?

The first inlet valve was removed from the cylinder head. It would be possible to do this with the cylinders in-situ but much easier on a bench. A quick bit of fettling on a section of aluminium tube and a valve spring compressor tool was sorted.

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The valves themselves are unusual. I shouldn't really be surprised any more but I was left wondering "Why do that?" while peering at a very fat but hollow valve stem. The conclusion reached the hollow bit was to reduce unsprung mass, but why such a large diameter stem?

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The original lapping marks are still on the valve and will need no work before reassembly. 

Each inlet housing had a oil pipe connected to it, and originally I thought these were for fuel injection. Now disassembled its apparent these oil pipes are for lubrication, with each of the 8 valves having its own oil feed. 

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So...the air/fuel mixing must have occurred before reaching the inlet manifold. A dig into some of the documents from the National Archives for a  MK VIII 21" torpedo reveals fuel consumption in the range of 60-70 oz/min at 200psi. So pressurised fuel was sprayed under pressure into the manifold. This part - the injector - is missing from the 8-cylinder example but they do quote the nozzle diameter of 0.04" so there is something to start with, as opposed to a blank sheet.

Somewhere, out there, a pair MK VIII torpedo fuel injectors must exist?

The bronze lump from the aux end - the finely machined barrel and its fine gearing - was originally thought to be some form of fuel injector. Clearly its not, but it is distributing lube oil around the engine. That goes some way to explain why I couldn't find any hint of timing marks on the gears!

The next job was to make access to the remaining cylinder head bolts a little easier and remove all 16 1/4"BSF studs that hold the cylinder lubrication feed pipes. Most came undone with a pair of nuts nipped up and only a couple will need a stud extractor:

SBrown-20190312-0010.jpg.ebab07f0e952f8c20c0dc5f186b945bf.jpg

 

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Hi Simon,

 

Thanks for sharing your project with us, it is without doubt the most interesting engine restoration on the web.

 

Andy

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12 minutes ago, racer said:

Thanks for sharing your project with us, it is without doubt the most interesting engine restoration on the web.

Its a pleasure Andy. TBH I was a little surprised in the interest. I thought it was just me being curious.

 

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3 minutes ago, SimonBrown said:

Its a pleasure Andy. TBH I was a little surprised in the interest. I thought it was just me being curious.

 

Ha! Torpedo engine, not interesting? Are you kindding! They are fascinating machines.

Love to see this one restored.

Shame there's not more stuff to see around Portland/Wyke about them...

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38 minutes ago, racer said:

Hi Simon,

 

Thanks for sharing your project with us, it is without doubt the most interesting engine restoration on the web.

 

Andy

Agreed

I am learning a lot, have been showing the 3D pictures to the office

Richard

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Posted (edited)

Well I am glad its not just me then!

10 hours ago, BRDM Driver said:

Ha! Torpedo engine, not interesting? Are you kindding! They are fascinating machines.

Wait till you see the big end. I have peered into the crankcase and have never seen anything quite like this bad boy before.

Single big end journal carrying four connecting rods none of which have end caps...Someone wanted a very compact design and the engineers delivered exactly that.

Hopefully a new tool will arrive in the next week or so and I can get the cam off to reveal all.

Edited by SimonBrown

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What an amazing piece of engineering.  The Explosion museum in Gosport may be able to help with Mk VIII injector information?

Andy

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Posted (edited)

The steel blank and tube arrived in the post this week so it was time to start fabricating the second engine mount.

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The plate comes plasma cut to whatever size you need. First up, drill the mounting holes

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And with minimal fettling, it fitted over the studs a treat:

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Now I do realise a wooden welding bench is less than ideal...

SBrown-20190324-0006.jpg.3ac4de5e4efd8f51ffc7e20c6edf8b1e.jpg

...But with a few bricks and care the job was done and nothing burnt down. Are the welds pretty? No, they are not - still working on that - but its unlikely they are going to fail anytime soon.

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So, once the cam is off the engine can be turned around on its stand and the drive case removed.

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There was a little distortion in the plate after welding but it slipped back onto the crankcase.

In the meantime another visit to the National Archives is planned. One of the documents is entitled "Torpedo engine operation without water cooling" which will no doubt simply tell me how long it can run before seizing.

Don't worry, have no intentions of destroying this engine  work of art...curiosity got the better of me, and it would be a shame for all that research go to waste.

 

SBrown-20190324-0015.jpg

Edited by SimonBrown
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Simon,

 

The special tool for the cam plug is in the post to you.  We all cannot wait to see what is revealed next!

 

John

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