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Tomo.T

Another J Type on the way !

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I also gave the bespoke seat a coat of Service Colour and it now looks less incongruous with its surroundings.

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Wonderful to see these works in progress!  I'm constantly amazed at the skills and knowledge that the craftsmen on HMVF display on a regular basis.  

Al

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Al, Thanks for the kind words. I am a relatively new boy here,  riding on the backs of the true pioneers, who have inspired me to emulate them.

Tomo

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Posted (edited)

Sump Update.

After careful consideration and a failed welding experiment. (Yes it's true, early cast ally does not weld !) I have opted for chemical assistance. Kes produced a first rate blasting job removing all the corrosion with just soda and a very low air pressure. He managed this without significantly enlarging any pinholes. Good Man. At the same time I happened across a bargain pack of Belzona 1111 on eBay. Buy it now it said, so I did. Although rather old, it was still viable, so I spent a few hours honing my sculpturing skills and this was the result. I think I shall call it ' Polished Turd Reclining.

 

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Edited by Tomo.T
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That of course, is the million dollar question. However, the stuff has cured to a rock like consistency and a good rub down with 80 grit produced fairly minimal result. I am quietly confident, but will test with deisel before use. 

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I had (still have) a cracked crankcase on an Austin 7. Also aluminium. I had another but changing the crank, cam etc seemed so much of a ball ache, i used some fuel tank sealer painted on the inside. It has never leaked oil. And is currently doing service on my chummy. 

It was the white stuff that Paul Beck used to sell. 

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2 hours ago, Tomo.T said:

 I spent a few hours honing my sculpturing skills and this was the result.

Looks pretty good to me. 

I wonder if you could metal-spray it with aluminium to make it look like solid metal again? 

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Ah, not a problem. The originals were painted service green along with the rest of the engine. Once I have checked for porosity I will etch prime and paint accordingly.

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5 hours ago, Tomo.T said:

Sump Update.

 At the same time I happened across a bargain pack of Belzona 1111 on eBay. Buy it now it said, so I did. Although rather old, it was still viable,

 

 

Belzona is excellent, and used in heavy industry. MoD use it and I have used it successfully in all sorts of applications.

regards Richard

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On 5/19/2019 at 9:25 PM, Tomo.T said:

Sump Update.

After careful consideration and a failed welding experiment. (Yes it's true, early cast ally does not weld !) I have opted for chemical assistance. Kes produced a first rate blasting job removing all the corrosion with just soda and a very low air pressure. He managed this without significantly enlarging any pinholes. Good Man. At the same time I happened across a bargain pack of Belzona 1111 on eBay. Buy it now it said, so I did. Although rather old, it was still viable, so I spent a few hours honing my sculpturing skills and this was the result. I think I shall call it ' Polished Turd Reclining.

Tomo, you should have seen the other one at the auction! It came with the other engine, but was corroded through and cracked. The good doctor asked if he could keep it as a chook feeder, and I agreed. Ian

 

 

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More Meat.

Went for a piston tugging session at Stan's workshop. The omens were good as No 4 came out by hand after I found the piston was turning in the bore. The others were not so keen so Stan created an impromptu jacking device which was simple, but effective. This comprised a piece of good solid plate bolted through the con rod big end holes and then jacked up with a pair of home made turn buckles underneath. Two large nuts were tacked below the plate to prevent any 'walking'.  Each piston in turn was jacked and blocked and gave little resistance once the initial reluctance was overcome. 

The pistons once cleaned, were in good order with free rings. Bores are good until you get above the pistons, where there is some pitting unfortunately. Further investigation continues.

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All pistons are marked 30.C on the tops. This should mean +30 thou. Size C, which was the only oversize piston available post war. In fact the pistons measure just under +20 thou. and have been turned down to match worn bores, with their top corners rounded off to avoid the step , ( just visible in the previous pics.)  This apparently was common practice in the day.  During the war no oversize pistons were supplied and the Army ended up casting their own at Base Workshops to prolong the life of engines.

Info; "Auriga" Book of the Thornycroft  p.87-89

The plan is therefore to attempt to fit liners to standard size A and turn down the pistons to match. This all depends on the remaining wall thickness, which is due to be measured with an ultrasonic gismo by an ex Williams racing engineer on Friday. Exciting stuff this isn't it ?

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Posted (edited)

Plenty Meat Update.

The ultrasonic gubbins has recorded wall thickness in the 9's and 10's (mm) with a one off low of 7.8 this is well good enough to fit a standard liner and the pistons will be turned down to suit as was originally intended.

This is wonderful news and I was surprised to hear the good thickness readings, which must be down to reduced corrosion on the water side. The only downer is the radiused corners on the piston tops, but that's not going to stop it running and everything else will be as standard.

One question, will I need new rings or just re gap the old ones ? The difference in bores will be 20 thou. smaller.

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Edited by Tomo.T
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Put them in the bore when (I assume Mike) has bored the cylinders for you and the liners are in place.

If they fit well go for it, if they don't make some new ones.

Young James Allison seems to have cracked making rings round here. I believe turns them to size plus a magic number (which isn't big by the sounds of it, but seems to be a trade secret). Puts a junior haxsaw through them, springs them out using a spacer and waves the gas axe at them to get them to a certain colour. Then lets them cool and gaps them Then they are good to go.

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7 hours ago, Tomo.T said:

Plenty Meat Update.

The ultrasonic gubbins has recorded wall thickness in the 9's and 10's (mm) with a one off low of 7.8 this is well good enough to fit a standard liner and the pistons will be turned down to suit as was originally intended.

 

If are looking for liners, I use Westwood Cylinder Liners, they have stock sizes or will make to your spec. Sometimes you might find the right diameter but slightly longer, my machinist cuts them to length before fitting them. Then you bore to required size.

regards, Richard

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On 5/23/2019 at 7:22 AM, Tomo.T said:

"Auriga" Book of the Thornycroft

First time I had heard of this book, however at the prices being asked will not add it to my library. Nevertheless it would be a good read, I am sure.

Ian

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Posted (edited)

Part of the Pitmans range of motoring books, written by an ex ASC ( Sergeant ?) and full of useful information about the dawn of Mechanical Transport generally and Thornycrofts in particular. Originally 2/6 d ( arf a crown ) I bought mine at £80 (Ouch) but have found it invaluable and have read it cover to cover except for the hard sums !

Tomo

Edited by Tomo.T
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Generally speaking this engine is in remarkably good order. It has done some work, following an extensive rebuild, but never run short of oil or attention and was looked after well prior to being laid up. Many of the components look fit for further service, but there are some pockets of corrosion. This inlet valve had the misfortune to come to rest in the open position when the engine was last run, a little water ingress is all you need, plus sulphur and carbon deposits, et voila !

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If you struggle to find replacement valves, these guys are really helpful.

http://www.gsvalves.co.uk/

Most of the valves on my Vulcan were in a similar condition to yours and I had a full set made. Very pleased with the results.

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The remaining metal is probably a bigger diameter than you would find on a modern valve. though I still don't think I would risk it. 

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Our valves were all made by G & S and the liners by Westwood. Both gave first rate service.

Steve  :)

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Worked out a method for storing my valves in a neat and orderly fashion. I tried various methods but this one actually worked. The valves are poked through a box from underneath with a 2 inch collar of wound up corrugated cardboard placed over the stems inside, which puts just sufficient tension on the springs to stop the pesky collets escaping. Details can then be written on the inside of the box.  Hey presto, all my ducks in a line !  Probably wasting my time, as the stems seem quite worn ( no lubrication ?) and one is badly necked as shown. I can see a new set being ordered from G&S. The springs and collets seem fine though.

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Posted (edited)

Apart from that I have been cleaning parts and surfaces and also gave the cylinder drain cocks a birthday. One of which is going to need a handle

 

Interesting news has arrived from the Antipodes concerning this engine, which was apparently bought as a replacement unit via Thornycroft Australia. It has always seemed odd that it has a full set of early features but a post war (badge) number. My thoughts are, it may have been a factory refurbished engine from war stocks. Which would suit me very well of course. I look forward to hearing more details.

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Edited by Tomo.T

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Posted (edited)

Mike Lewenden has performed wonders with the oil pump and it has been bushed and all its excessive clearances dealt with, to such an extent that it was now slightly stiff to turn. Stan improved the situation with a little compound and I put my mind to creating a flexible drive 'whizzer' to complete the 'lapping in 'process.

The pic is self explanatory and Stan even took a video of the machine in action. Needless to say the pump now turns over sweetly and is ready for some oily action.

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Edited by Tomo.T

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