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WW1 Thornycroft restoration


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One question I would like to ask is how tight should they be? I just keep going until I think they feel 'right' but I have no idea what that should be! I must say, though, that we were subject to official supervision throughout the process.

 

 

 

 

 

Hi Steve,

I use Plastigage to check clearances, it is a sort of wax strip, round in section of a certain diameter, you lay I it on the journal with a spot of grease to hold in place, then fit the cap, do not turn, remove cap and with the guage card that comes with it, you measure how much the strip has squashed out, that gives you the clearance. Here is a web link, there are others, but I do recommended it.

http://www.carcraft.com/techfaq/116_0701_plastigage_vs_micrometer/

 

regards, Richard

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The plastigauge sounds interesting, especially when you start with a bearing that 'fits' already. As you have seen I am machining the bearings of the Peugeot to the approximate size prior to scrape them in, so I have to measure them before I can start to scrape. From what I have heard a rule of thumb is 0.001" per inch diameter, or 0,01mm per 10mm diameter.

 

Merry Christmas!

Marcel

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The plastigauge sounds interesting, especially when you start with a bearing that 'fits' already. As you have seen I am machining the bearings of the Peugeot to the approximate size prior to scrape them in, so I have to measure them before I can start to scrape. From what I have heard a rule of thumb is 0.001" per inch diameter, or 0,01mm per 10mm diameter.

 

Merry Christmas!

Marcel

 

Hi Marcel,

Here is a link to Ebay, http://www.ebay.co.uk/sch/?_from=R40&_trksid=m38&_nkw=plastigage They are colour coded in different sizes, you will need the Red one I guess, that is what I have always used for cranks and big ends.

 

regards, Richard

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Thanks Richard. That's an interesting item I have not come across before.

 

Should the rods fall around the crank when fully tight or should there be some resistance? At the moment, I have two which fall freely and two which require a slight push. What I really need is to see an expert do it and then feel for myself!

 

Steve. :)

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Next part of the job is to assemble the blocks. Firstly, all of the necessary gaskets were marked out and cut using a pencil, rule, Stanley knife and wad punches

 

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Then the threads were cleaned up with a die nut before fitting the first cover. As the mating surfaces were so poor, red Hermetite was used to help the seal.

 

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Then all of the other covers were fitted including the pump mounting casting.

 

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This has proven to be more than a day's work but the results are quite pleasing. The next task is to gap and fit the rings before permanently setting up the rods on the crank.

 

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Plenty to do tomorrow!

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Quote " the co rod,without its piston,just will not fall of its own weight when set in a horizontal position , but if given a fairly sharp push from that position it should make about one complete revolution round the pin". From the motor repair manual

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Tim,

 

That was my thought as well, that the Albions were intended for Home Front use. I am assuming that it was the civilian liveried lorries in France that were repainted first, although some military ones might have been if they were in for overhaul. At some point, the decision was made to switch from military grey to GS, or whatever they called it. Certainly by mid-January 1915 repainting was happening among a lot of ASC companies and ambulance companies. My gut feeling is that that decision was made sometime in October or November 1914.

would tie in nicely with the discovery that cavalry were easy targets for machine guns....hence by the end of 1914 most were dismounted and put in with the infantry...further more green was a better colour for camouflage and the fact that trucks in service already were being repainted around this time (back end of 1914) is a clear indication that the government & general staff could see that this war was going to last a lot longer than had been expected as both sides dug in...
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Thanks Chris. That is a very good piece of guidance. I'm just going out to scrape a little more as I have torqued up the first big end completely and it is just a little too tight.

 

More later. Happy Christmas everyone!

 

Steve:)

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After fitting all the gaskets and covers, the next step has been to 'gap the rings'. The rings we have are for 110mm bore which is slightly bigger than the 4 5/16" of our liners so I have dressed the ends back to give a clearance between them of 0.012". A gap of 0.002-0.003" per inch of bore is recommended on the scraper ring packaging so I have simply followed that.

 

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Unfortunately, after completing fifteen rings, I had a disappointment when I found that the last scraper ring was too small and already had a gap of about 3/8".

 

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All of the packets were correctly marked but one is undersize. I shall have to contact the supplier in the New Year but it is a bit of a disappointment as we cannot do much more to the engine. I can do a bit though so I have fitted the first piston to a rod by pushing the gudgeon pin into the newly honed bore. It went beautifully and I had then only to fit the re-sized spring clip to secure it

 

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Disaster! I have obviously not got my heat treatment quite right and two of the clips broke in my hands. Closer inspection revealed cracks at the breaks but it was most annoying.

 

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I softened the two remaining clips a bit further and my third attempt at fitting one was successful and worked a treat.

 

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Then the other rings were fitted uneventfully and the rod was ready for the engine.

 

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When fully torqued, the bearing was a bit tight but another blue and scrape sorted that and the rod is now secured and pinned. I will try to do another tomorrow and perhaps we can at least get the front block fitted.

 

Steve :-)

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We started today where we left off yesterday by fitting another piston to number two rod, securing it with the spring clip without breaking it and then by fitting the remaining rings. This all went well and the rod was bolted to the crank and tightened right up. This showed the bearing to still be a little tight but a couple of scrapes soon sorted it and the nuts were secured with split pins. Two rods down.

 

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A brief intermission was taken to salvage four spring clips from the other pistons ready for cleaning up and reducing in size to fit the smaller pistons.

 

DSCN9660c.jpg

 

That achieved, we decided to fit one block to protect the rings and see how it all looked. The chain block was used to raise it and the engine was wheeled underneath.

 

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After wiping the bore and pistons with an oily rag, Dad slowly lowered the block whilst I poked the rings in with a piece of wood and a screwdriver. I remembered from the Dennis that pushing the rings with ones finger tips is not a good idea as the block can suddenly drop, trimming one's finger nail, if not more!

 

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Once fully down, the block was held with 5/8" nuts on the new studs made earlier. The cam followers were also fitted and clamped down.

 

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At this point, I wanted to grind the valves in but was dismayed to find that our re-cut valve seats have dropped so far that there is no longer any tappet clearance.

 

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I need to find about 0.060" and propose doing this by trimming the end of the valves and possibly facing a little from the tappet. I would prefer to trim only the tappet but there is just not enough metal there. Another challenge to be overcome!

 

Steve :)

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Hi Andy.

 

No, we haven't fitted a gasket under the block. We had some debate about it but as there was none there when we took it apart and it isn't mentioned in the parts book, we decided not to. It would, however, have helped with the tappet clearance!

 

Steve :-)

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Hi Andy.

 

No, we haven't fitted a gasket under the block. We had some debate about it but as there was none there when we took it apart and it isn't mentioned in the parts book, we decided not to. It would, however, have helped with the tappet clearance!

 

Steve :-)

 

Steve,

Personally I would not have used a gasket either, with Red Hermetite, Stag or similar this will be more stable joint and surfaces are good.

Motorcycle barrels did not have gaskets between them and crankcase, in my experience, but could have shims under them to adjust compression.

 

Looking good, making great progress here.

 

regards, Richard

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Its great to see this engine come together!

 

In regards to a gasket between the blocks and crankcase - On my T-head Wisconsin they used thin paper gaskets. They were nothing more than shellac coasted brown paper. The gasket and the block were assembled while the shellac was wet. In fact all the gaskets were done this way.

 

Best regards,

 

Terry

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Everything we take off is kept until the end. Real scrap, bushes and pins and such like will be binned but the old pistons will be labelled and boxed and go into store. Silly really but they might be useful to somebody one day.

 

Steve :-)

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if one would be scrap, i would like to have it. polished and preserved i would use it as a paper weight :-)

i have another item, conrod and piston bend to buggery but mounted on a plank it is a trophy of stupidity (not quitting land-rovers in the first month)

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I'm in Dubai, restoring a little three-wheeler truck that spent its working life soaked in seawater with predictable results. I've been stuck on a few occasions, but your thread has made my tribulations seem completely insignificant and got me going again, plus taught me a whole heap of new techniques in the process. I've found very little else so completely beguiling on the entire web; congratulations on a fantastic story, a wonderful blog and a superbly worthwhile enterprise. I look forward to meeting you both and your Thorny in due course.

 

You should be on the national syllabus as an example of what's possible given some good engineering nous, a bit of British grit and a decent shed.

 

With sincere good wishes from a distant foreign outpost,

Will

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if one would be scrap, i would like to have it. polished and preserved i would use it as a paper weight :-)

i have another item, conrod and piston bend to buggery but mounted on a plank it is a trophy of stupidity (not quitting land-rovers in the first month)

 

I'm sure that would be fine but I don't want to part with anything until we have completed the job. I have been caught that way before!

 

Keep in touch!

 

Steve :-)

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I don't have much to say apart from how much I enjoy and apreciate your rebuild and the associated thread. Thank you for making all this available.

 

Thanks again, reegards, Matthew

 

Thanks Matt. I'm glad you haven't got bored with it yet! Perhaps we will meet on Brighton seafront again next year. We are hoping for nine Great War vehicles this time so it should be worth seeing!

 

Steve. :-)

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I'm in Dubai.....

 

Hi Will.

 

Many thanks for your kind comments. It is wonderful for us to be able to share our pastime with so many friends we have never met. We have had so much advice and encouragement and it is most gratifying to think we can encourage someone else in their project. I am convinced that anyone can do this sort of thing, though. You just have to want to do it!

 

Good luck with the three wheeler!

 

Steve :-)

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Thanks Matt. I'm glad you haven't got bored with it yet! Perhaps we will meet on Brighton seafront again next year. We are hoping for nine Great War vehicles this time so it should be worth seeing!

 

Steve. :-)

 

Steve,

 

I don't know whether or not I'll get across the channel for the next Brighton run, I hope so!

 

Thanks again, Matthew

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  • 2 weeks later...
Should the rods fall around the crank when fully tight or should there be some resistance?

 

I think that the "rule of thumb" is somewhere between 0.5 and 1 thou per inch diameter clearance (as measured by Plastigage) In practice this seems to end up as "slight nudge" when new, and rather free-er after a few minutes of running.

 

We made the breakthrough of pouring and boring our own big-end bearings on LP8389 a couple of years ago, and the one we did is still going strong. The kit and materials are all there at IC if you need to do one.

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