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WW1 Thornycroft restoration

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Quick thought...

Is the seizing possibly  due to still running rather lean and rather hot? Probably not, as one might anticipate steam and other obvious signs on a vehicle with this style of cooling system.

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Thanks Chaps. To be honest, it was quite a successful day really. We did take it on the road on the day we planned. We just didn't get very far!

Today, our old friend Dave came and had a look. He is a retired motor mechanic and keen rebuilder of motor cycles. He has helped us a tremendous amount over the years with advice and assistance and we value his opinion very highly. We ran the lorry for him and it started very easily. We seem to have that bit nailed now anyway! It was very smooth and nice and, when switched off just ran down as you might expect rather than stopping sharply with stiffness. I started it again and, although stiffer than when cold, rotated OK. His considered view is that it is almost certainly tight in the bore and he thought that it should have nearer 0.008" clearance. However, rather than pull it down for the moment, he would keep it running for a few hours at a fast idle and see how it goes so we plan to do that. Failing that, he has the appropriate honing equipment and would be pleased to have a go at the bores for us if we drop them off with him and handle them.

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We have run it for another hour today until the fuel ran out. I put some more in the tank and then tried to swing it but after those few minutes, it had tightened up a lot and I couldn't turn it. In fact, I have pulled something trying so I thought that a good moment to stop! I have a couple more days of holiday so we will run it again and see what happens before putting it back into the shed.

In answer to Andy's comment, it is running rich now due to my oversize jet. I shall make some more, when I get home, of slightly smaller bore. In the mean time, we are doing some bits of the body ironwork before going back to the wing irons. I would like to finish off the floor shortly as well. It is interesting watching the clutch operate beneath one's feet but I should hate for someone to put their foot through it!

Steve    :)

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20 minutes ago, Old Bill said:

His considered view is that it is almost certainly tight in the bore and he thought that it should have nearer 0.008" clearance.

...

Failing that, he has the appropriate honing equipment and would be pleased to have a go at the bores for us if we drop them off with him and handle them.

Am I misremembering, or did you turn the pistons to size?

My conservative instincts have me preferring shrinking pistons to expanding bores,  just because bores are much harder to re-make. 

Inspection might make it clearer which way to go. If it turns out to be the top ring-land that is looking all shiny then I would look at rethinking the steps. 

 

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Steve

I would suggest that a pull down is the only real option. Persevering given the behaviour of the engine will probably not see any improvement and at best can only "make metal" as whatever is binding has to be scraped away and will then end up in the oil. We are not talking shoes "wearing them in" so that they become more supple.

If the pistons are too large then I tend to think they will scour badly, if they leave material behind on the cylinder walls this is not healthy for the rings, possibly resulting in a broken ring.

IIRC this vehicle has no oil filter, so that means the metal shavings will then circulate in your engine. Not a desirable scenario.

Sorry, but hoping it will "wear in" is being confused here with "bedding in".  

Regards

Doug

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12 hours ago, dgrev said:

IIRC this vehicle has no oil filter, so that means the metal shavings will then circulate in your engine. 

Steve,

I can't remember but is the sump plug magnetic. As we all know, it is not a replacement for a filter but it is amazing the amount that the magnet catches. 

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Thanks for all of your thoughts Chaps. I am still pondering at the moment as I am not much good at instant action I'm afraid. We haven't run it today as I pulled something yesterday and now have blue biceps! Driving a desk isn't good practice for this hobby! In the mean time, we have been gently pottering along, making capping strips and edging strips for the tailboard. I have also fitted some reflectors as a concession to modern traffic.I shall have a go at the floor tomorrow and then the wing irons. I am not really looking forward to them but they need to be done.

The sump plug is not magnetic. However, the pump draws through a strainer so major lumps of metal shouldn't get in. The fine stuff will so we will end up with another oil change soon, I guess.

Steve     :)

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I've been following this in the background for years and only really recently joined up because of your amazing adventures rebuilding this lovely old beast...

As the time got closer to the run I could feel the tension and anticipation for the outing, (obviously not as much as yourselves) but enough that I was almost heartbroken for you all after having to make that hard decision.

Anyway I digress, congratulations on saving this old truck your skill and patience is truly admirable!

I know its not the done thing, but none of us are getting any younger and a pulled muscle or a damaged back while trying to start an old engine is something to avoid,, so could you not use a battery powered impact driver to turn the engine over (without any hammer action) to avoid such injuries?

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Hi Scott.

Glad you have been enjoying it. Yes, the tension was certainly there this time, more so than with the Dennis. We were much further on with that one at this stage. It is very disappointing but was quite a big ask to be 100% right first time after such a big rebuild. We did put it on the road on the day we promised though!

Starting the thing is always an issue with these old vehicles and not many of my friends can swing it. I think it is technique as much as anything. I must say that there is great satisfaction in a hand start but sooner or later I may have to give in. At least one of my friends has rigged up an electric start on his bus but has managed to do it without drilling any holes in the chassis. The intermediate stage is to fit an impulse starter and I certainly plan to do that. The Thorny isn't actually too bad when it is free. I hurt myself trying too hard on a stiff engine but have now learned that lesson! I don't think an impact driver has enough torque to turn it but it is a good idea. I have seen a starter rigged up using a chainsaw engine and gearbox attached to two long bars and engaged in the starting dog. It worked but took two people to hold it!

I need to start the thing again this morning so that we can put it back in the shed. I shall be more careful this time.

Steve   :)

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1 hour ago, Old Bill said:

The intermediate stage is to fit an impulse starter and I certainly plan to do that.

I am somewhat surprised that it doesn't have a twin-ignition system with a trembler coil like our Dennis does. 

But then I don't think anyone could ever swing that fast enough to get the magneto to catch, it is as much as most of us can do to pull it over the top. 

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(Quote) have seen a starter rigged up using a chainsaw engine and gearbox attached to two long bars and engaged in the starting dog (end quote) 

in ww2 a system was used powered by motorbike, powering a rod system that engaged the starter dog. Might be fun to build, i know i want one now to use a dirt bike to start the diesel! 

looking forward to meet you guys, ever plan closer to Lincolnshire or Northants to visit shows? Would be fun and a privilege to sit in the truck. 

 

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Ah yes but you are talking about a fire engine with 9 1/2 l engine. These army lorries are only 6 1/2 l and they didn't feel the need to fit them with impulse or trembler. They were also driven by 18-25 year olds, not old fogies like us!

Steve   :) 

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3 hours ago, .303fan said:

in ww2 a system was used powered by motorbike, powering a rod system that engaged the starter dog.

The twins restored/built one in an episode of Combat Dealers.

WW1 answer to the problem of hand starting:-

 

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Hi Steve, I think an impulse is the way to go. If you prime the engine you don't have to swing it around anymore. A couple of quarter turn pulls will suffice. Regards, Marcel

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I have seen a few starting aids using engines or geared starter motors. The main  thing to be aware of is the immense reactionary torque. They have to be secure - just holding a battery ratchet driver will turn you somersaults!

Ian

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20 hours ago, MatchFuzee said:

The twins restored/built one in an episode of Combat Dealers.

WW1 answer to the problem of hand starting:-

 

Indeed they did, loved the concept of it and made me think of a excuse to keep hold of the 125cc dirtbike. 

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Although the Thorny couldn't make it to Brighton we went down to see everything coming in. An incredibly hot day so thousands of people descended onto the town. Trains all cancelled so everyone came by bus or car. The traffic was very bad and with the judging time expiring at 14:00 i think more than half of the vehicles had not arrived.

Of the WW1 vehicles entered two Y Types withdrew, the LGOC and FWD broke down on the way. Pierce Arrow made good time followed by Grahams Y and the Hallford. Star of the show was for me which Liberty B which looked great and on occasion towed the Saurer and the FWD up a hill. A grand day out and nice to meet so many friends.

 

 

 

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Posted (edited)

If you are going to consider easier starting, here in the States the early big car guys have worked out a very slick set up. They run a 12 volt starter Generator combination from a small desiel lawn mower. They use a small gel cell battery for power/storage, and a flat belt around the flywheel. The whole thing is very compact, and can usually use existing frame holes or clamp on brackets. It requires almost no wires except the starting button that can be well hidden. The unit is whisper quiet, and works quite reliable. Price is very reasonable and installation with proper planning is usually a breeze, and can be removed for judging easily when required. I have seen this set up spin a twelve liter engine. Many of us here across the pond enjoy watching your projects, and I often hear people commenting about you gentlemen at car shows. Truly a global initiative! Last summer for the second year in a row we brought a car over to tour the Cotswolds, a wonderful place to drive a car. The roads can be quite narrow, and driving on the opposite side in a 85 year old large car can be quite a challenge. I hope to see you at Brighton in the next year or two, as we are hoping to get a pre 1904 machine to make the run. The photo below is on the road to Broadway. Thank you for the many hours of entertainment you provide all of us every year! Cheers! Ed.

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Edited by edinmass

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Posted (edited)

I was intrigued by the last post from Ed. I have a 1913 Merryweather fire engine where starting is quite difficult, due to the engine size and compression. In the U.K. starter/generators are called DynaStarts. The advantage being is that the belt drive is permanently engaged and once you have used the 'Start' part of the unit the 'Dyna' part charges your battery. For the Thorny and my size of engine (10 litres) you need quite a big DynaStart. There is a man on ebay specialising in Dynastarters for our type of application and typically sells 10 sets a year. The best belt to use is a 'Polyvee' belt, which you see wrapped around serpentine like on all the Front End Auxiliary Drives on large car engines. These are like 4 or more tiny vee belts all joined together side by side. A pulley ratio of 6:1 will give a torque of 60 ft lbs at the crank. How does that compare with Steve giving the hand crank a good swing? Probably about the same? Anyway, I think I am going to give it a try. The seller will accept everything back if it doesn't work and give an 80% refund which seems quite fair.

The great advantage of this type of unit is that you don't have to fit a starter gear ring to the flywheel or do any machining at all. With luck the DynaStarter can just be clamped onto chassis rails without any hole drilling, so the system can be removed without leaving any traces behind if you wish to go back to complete originality.

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Edited by Asciidv

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10 minutes ago, Asciidv said:

I was intrigued by the last post from Ed. I have a 1913 Merryweather fire engine where starting is quite difficult, due to the engine size and compression. In the U.K. starter/generators are called DynaStarts.

They are making something of a comeback with "belt ISG" (Integrated starter/generator) on so-called "microhybrid" vehicles. 

 

If you can find one of those second hand it might be an option. You _probably_ don't need to fit a CAN bus to the Merryweather. 

 

Just make sure you set the belt tension correctly 🙂

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16 minutes ago, andypugh said:

Just make sure you set the belt tension correctly 🙂

I don't know if I know how to do that........

 

 

Here is a video of another starting system called B.E.N.

https://youtu.be/KwZL-JDnBuY

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12 minutes ago, Asciidv said:

Here is a video of another starting system called B.E.N.

https://youtu.be/KwZL-JDnBuY

Did they abandon the dual ignition on the later models then? Starting our 1916 is _reasonably_ easy. 

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9 minutes ago, andypugh said:

Did they abandon the dual ignition on the later models then? Starting our 1916 is _reasonably_ easy. 

Yes, later models were not fitted with the trembler coil.

This is how it can be started without B.E.N.

https://www.youtube.com/watch?v=ivN1FNsrCsI

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The Ebay advert above is very interesting. I have a small diesel narrow gauge loco with a two cylinder engine. It has provision for a dynamo for lighting but no provision for a starter. That unit would start it and look right too. Thanks

David

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Well, Brighton was a week ago and things are returning to normal. In other words, cooking, gardening and earning a living! This is how close we got to succeeding:

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It was a bit disappointing not to go but I am consoled by the fact that the traffic was terrible and it would have been a miserable drive. In the mean time, we didn't stop during the week but carried on without the pressure. We cut and fitted the tailboard hinge pin.

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And then went on to the wing brackets.

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I tacked them up ready for a proper welder to stick them together. Even my tacking is dreadful! I can't seem to get the weld to stick to both halves of a fillet at the same time. More practice needed I guess.

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Four rear brackets ready for welding. Once properly attached, I shall spend some time with the angle grinder and files to give them some shape.

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We had various friends around when we attempted to test-run the lorry and they have kindly sent me some photos.

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This is the somewhat daunting sight to be met coming out of Dad's driveway. I have to trust that I set the brakes up correctly!

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I mis-judged the corner, however.

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Fifty yards further on, it stopped.

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Return to base.

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Steve.

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Posted (edited)

I looked over the thread and couldn’t find what you used for piston clearance. A minimum for this application should be .007 and a max of .010 . I wonder if the liners are causing a heat transfer problem with the block? Or possibly the home made pistons and material could also be an additional unknown as far as expansion goes. After many years in the hobby we have learned to run an engine on a stand or dyno for several hours before installing it. I know you gentlemen are pressed for room and are working on a time as available schedual, and it would not have been practicle  for you to run it out of the truck. With the amount of service the truck will ever see, and modern oils having made great strides from when the truck was new, I would set up the piston as loose as you dare. You may get some cold start up slap, but once warm it should run quiet. On our cars with a six inch bore we run .012 and they have worked out fine. Once the motor is properly broken in, you can switch over to 100 percent synthetic motor oil. That way there will never be a scoring issue or oil failure with major damage. Depending on cost and time, maybe a modern set of pistons with modern ring packages would be worth considering. You could have them made so you only need to do a light hone and reassemble. The good news is the top end comes  apart relatively easily. You have done a great job on this truck. I wouldn’t call it a restoration, I would call it a resurrection! Job well done! The dedication your family has saving our history is truly inspiring. 

Edited by edinmass
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