Mike Macartney

REPORTS ON A 1914 HUMBERETTE RESTORATION

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Yes Al, she's a gem. We were in the same class at school since were eleven and started going out together when we were sixteen. This years in March was our 50th wedding anniversary.

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Those collets were a real score. You won't regret having them

 

jp

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To finish the other end of the 3/8 BSF nuts I started making this male threaded bar by turning it down to 3/8" diameter and cutting a 0.032" deep groove at the hex end.

 

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After threading the bar at 20 TPI (which I now found out that I forgot to photograph). . . .

 

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I threaded on each of the nuts, locked the cross slide and turned them all down to the same thickness using the graduated dial on the compound slide to get the thickness correct.

 

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I think this is the first time in my life that I have made a number of nuts that are all exactly the same thickness - thank you Joe.

 

Eventually, I have got around to drawing out the original piston and attempted to find modern pistons to use in place of the original cast iron pistons that are cracked.

 

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I have found these Ford Zetec pistons, with a few modifications,  maybe a suitable replacement for the original pistons.

 

Have any of you had any experience of honing jugs?

 

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A while back I bought this cylinder hone and two sets stones of four various grits. Any help or advice would be appreciated. 

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If you haven't done so already, you should check the bore for straightness. Is that a spring loaded hone? If so, it will follow the bore so if it's tapered you will still have a tapered bore after it's honed. The idea is to break up the surface so it isn't polished looking. There is a cross-hatching pattern that is supposed to be superior for modern chrome rings but I doubt it is necessary in an engine like this... I'd just pass the hone through the bore until all the glazing is gone and the surface is an even grey color.

Edited by JV Puleo (see edit history)
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I have finished making the 16 nuts for the engine. Now I need to make 8 threaded studs for the fixing the barrels (jugs) onto the crankcase. It sounds easy but when you are learning it seems to take forever. The outside diameter for 3/8 BSF x 20TPI thread, I would have thought, would be 3/8" or just under. On the nuts that I made, I used a tap to make the thread, the nuts fitted fine on the original stud sticking out of the alloy crankcase. I removed one of the existing studs from the crankcase and the thread was 3/8 BSF, or so I thought! When I tried one of my new nuts on the thread it would not fit.

 

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I measured the OD of the stud thread, on the section that fitted into the crankcase, and it was 0.007" to 008" larger than 3/8 BSF (0.385") thread. I am assuming that this was done on purpose to make sure that the stud was firmly fixed into the aluminium? It looks as if I will now have to make very slightly stepped studs.

 

Before I got fully 'stuck into' making all 8-studs I thought I would make just one to start with to check that my calculations were correct and work out the best method to make the other 7-studs.

 

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I have a number of secondhand lengths of 1/2" diameter stainless and I decided to use this material rather than buying some 3/8" diameter. After cleaning off the end which had an 1/8" drill hole across the end, I was ready to machine some of the bar down to 3/8".

 

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Turned down to 3/8" diameter, this was before I had realised that it should be larger than 3/8". Anyway, I went ahead and cut the 20TPI thread on the lathe to fit the nuts I had made. (again, I forgot to take a photo). By the way - the foam ring to stop the threaded ring from rattling is a failure! It is OK at low speed, but eventually flies out when the lathe is on a high speed, I wonder if I can make a threaded ring out of wood to fit in there?

 

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I parted off the stud at the length I wanted, changed the collet and was about to cut the thread on the other end. When I turned on the lathe the stud was running a long way out of true. It was about time for lunch, so I packed up and went back to the house. I might go out later for an hour or so to see what the problem is.

 

As an aside - I have had a search on eBay for a multi draw filing cabinet. One turned up not very far away from me and I bought it.

 

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It has 30 shallow draws which will be ideal for storing drills, reamers and the like. I lined a draw with corrugated cardboard, it looks as if this method will be ideal for keeping the tools apart.

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Nice! I could use one of those too.

re the studs...It is possible that you are just dealing with the slight differences in tolerance that old nuts and bolts suffer from. There is a good chance that the tool making dept at Humber made both the taps and dies and that, while they worked for them, they are slightly different than the modern versions. You can compensate for that easily enough. I'd do one end of all 8 studs first, then do the other end to a slightly different tolerance. If you are a few thousandths under the stud will screw in...and this is a good place to take advantage of modern adhesives like Locktite. Studs with one end slightly oversize so it is tight in the hole are still made.

 

Try the other end of the stud (where the nut goes) in the hole and see how it fits. If close enough, they can all be the same.

Edited by JV Puleo (see edit history)
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3 hours ago, JV Puleo said:

If you haven't done so already, you should check the bore for straightness. Is that a spring loaded hone?

 

I have not yet put the stones onto the hone. I had a look this afternoon after I received your last post and it looks as if there is very slight springing in the stone mountings but the majority of the adjustment is by the turning the knurled knob which adjusts the width of the hone to the bore. The standard bore of the engine is 84.25mm the pistons I need to go out to 84.5mm to get rid of the marks in the bores. The pistons I have found are 84.7mm. Do you think I am asking too much to hone out that much material?

 

2 hours ago, JV Puleo said:

I'd do one end of all 8 studs first, then do the other end to a slightly different tolerance. If you are a few thousandths under the stud will screw in...and this is a good place to take advantage of modern adhesives like Locktite.

 

The end of the stud that I cut for a standard 3/8 BSF thread, fits in the casing, to put it rudely, 'like a cock in a sock'! I can cut the threads, as you say, with a different tolerance.

 

2 hours ago, JV Puleo said:

Studs with one end slightly oversize so it is tight in the hole are still made.

 

I didn't realise that you could get these. At least, if I have a go at making 8-off, it will give me more practise at threading on the lathe. I will have a search to see what's available for future reference.

 

I appreciate your help.

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You should also check to see if there is room for a lock nut on the underside of the stud. These were often left out but if you can put them on it eliminates the purpose of slightly oversize threads since the tightening pressure is now on the stud and the nut. Mitchell left them out everywhere but I'm putting them in.

Hones only rough up the surface - we used to call them "glaze breakers"... I suspect taking .005 out would take a month - not being sure what those metric measurements come out to in thousandths.

 

One of the modern methods of boring a cylinder is with a powered hone...that would adjust the diameter and take some of the taper out but it's done with a specialized machine. A spring loaded hone is just going to follow the surface and won't do anything regarding taper. I think you really need to check for taper. In the days before air filters the bores wore quite fast. A car with relatively low mileage can still have badly tapered bores. I had to go .080 over size to get the taper out of mine and I doubt the engine has a lot of miles on it (it wouldn't have survived if it did).

 

I've never seen studs with two different tolerances offered in BSF but not being in the UK, I've never looked for them. There must be industrial suppliers that may have them. I'd just plug away at making them...no one is going to do a more conscientious job than you are.

 

Another thought... a split die in 3/8 BSF in a die holder with the adjustment screw in to open the hole in the die a bit. That may be how they were made in the first place. You'd cut the threads about 90% of the way on the lathe then run the die over them. Herbert's made a really neat lathe mounted die holder - I've never seen one but it was adjustable and was used with interchangeable dies. I think it was called a Coventry die head or die holder... makes sense since they were in Coventry.

 

jp

Edited by JV Puleo (see edit history)
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12 hours ago, JV Puleo said:

Another thought... a split die in 3/8 BSF in a die holder with the adjustment screw in to open the hole in the die a bit.

 

Why didn't I think of that! Thanks Joe.

 

12 hours ago, JV Puleo said:

I suspect taking .005 out would take a month - not being sure what those metric measurements come out to in thousandths.

 

0.3mm = 0.012" So I maybe at it for a couple of months! It maybe quicker to machine the piston?

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If it is a modern piston it is almost certainly cam ground so it isn't actually round. But, cam grinding wasn't invented until much later. The original pistons were round and cast iron. Modern aluminum pistons are cast or forged from alloys that have a very low coefficient of expansion but it will still be higher than the iron. Then you have to consider the depth of the ring grooves. It is probably doable but like all these things requires a lot of thought. It would almost certainly be more efficient to have the jugs bored to match the new pistons. The piston clearance should also be looked at. The clearances suggested for modern engines presume the use of an electric starter. I'm guessing that when the car is intended to be crank started perhaps the clearances should  be a tiny bit larger. (maybe .001-.002?) The pistons for my car - which I'm making myself from a pattern made by a good friend - were cast of 356T6 which is not a piston alloy and expands more than modern piston alloys do. I did this, partly because that is what the foundry next door could do and partly because the Mitchell is a crank start car. I may get a tiny amount of piston slap when the engine is cold but it will warm up and the ability to turn it over easily for starting is important.

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Joe, I have used fairly modern alloy pistons before, in my vintage motorcycles, I modified a new Ford Escort piston to fit in my Humber 350cc sv motorcycle and also fitted one in a 1922 Abingdon King Dick 500cc motorcycle that I used to own. I can't now remember exactly what piston I used for the AKD, but VW comes to mind. Both of these were air cooled; of course the Humber engine is water cooled, although I doubt if that makes any difference. Finding somebody to bore out the 'jugs' seems is a bit of a problem at present. So far I have had no luck searching on the internet for a company that can bore blind barrels. That's why I thought of trying to hone the jugs out to fit the pistons myself. Perhaps, I will have to resort to ringing a few engine reconditioning companies and asking if they know of any companies that can undertake the work at a reasonable price.

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I think the ideal machine would be one of the old Van Norman cylinder boring tools. It was literally a "portable" unit and years ago, when this was a lot more common, there were guys that would come to your house and bore an engine one hole at the time. Those machines clamp to the flanges on the bottom of the jug so they are ideal for blind hole boring. I don't know how common they were in the UK or if you had a similar machine but its the sort of tool that vintage motorcycle shops have (or had).

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20 hours ago, Mike Macartney said:

 

0.3mm = 0.012" So I maybe at it for a couple of months!

 

20 hours ago, Mike Macartney said:

It maybe quicker to machine the piston?

 

I was wondering about turning down the piston some how. I read this is not your first go at adapting an entirely different modern piston to a very vintage engine.

 

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6 hours ago, JV Puleo said:

I think the ideal machine would be one of the old Van Norman cylinder boring tools. It was literally a "portable" unit and years ago, when this was a lot more common, there were guys that would come to your house and bore an engine one hole at the time.

 

What like this!

 

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This person came to our Jaymic workshop to bore out a London Taxi engine, when I designed a way of converting the Nissan TD27 engine to run on LPG, instead of diesel fuel. We converted a number of London 'Black' Cabs to be used in London.  This taxi is the first one we did as an experiment to see if it worked.

 

I did not realise that you could use one of these machines to bore a 'jug'. I thought the machine had to clamp to the engine block. I think I know somebody locally who has one of these borers. I will give him a ring next week.

 

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A collage of the work we did.

Edited by Mike Macartney
added text (see edit history)
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4 hours ago, mike6024 said:

I was wondering about turning down the piston some how.

 

The thought had also crossed my mind.

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Yes... one of those.

Van Norman and Kwik Way also made a stand usually used to old Motorcycle cylinders. There is no great challenge to blind boring aside from measuring the depth and knowing where to stop. The combustion chamber, at the top of the jug isn't bored so the bored surface stops before it reaches the top.

Edited by JV Puleo (see edit history)
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Thanks for that Joe. I am pretty sure the guy who has the borer does not have a stand. If I can contact him next week I can go and have a look and see what he has.

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Failing a stand... you could make a plate about 8" square with a hole in the center and countersunk holes for flat head cap screws. This would be attached to the  bottom of the jug to give a large flat surface around the hole. That could increase the clamping surface as much as needed to attach the machine. It would be a bit of work but the piece would work for both jugs.

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I am sure interested to see how the boring job comes about for you and then fitting with modern pistons.

Al

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20 hours ago, alsfarms said:

the boring job

 

I had not thought about it before; did possibly the name 'boring' come about due to the process being rather laborious?

 

23 hours ago, JV Puleo said:

Failing a stand... you could make a plate about 8" square with a hole in the center and countersunk holes for flat head cap screws.

 

I'll find out what engine boring equipment Martin has, if I can get hold of him next week, he is about my age so it is possible that he may have now retired and got rid of his equipment. Being situated in rural North Norfolk has its advantages, but the lack of engineering facilities in the area can be a drawback sometimes.

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I did go and see the engine builder yesterday and he does still work but only four days a week. I have 'bottled out' of boring and honing the jugs myself and have left a new piston and the jugs with him. I was hoping to do as much of the work on the Humberette myself, but sometimes you just have to know your limitations and the equipment you have to do the job.

 

Next job was to make some new studs for the barrels.

 

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I removed the old ones quite easily by screwing on two nuts, tightening the two nuts together and undoing the lower nut which then unscrews with the stud attached (I have only explained this because, there maybe some readers who don't know this method, I apologise to those that do).

 

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Here is the unscrewing part of the job!

 

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I measured the approximate depth before the flywheels would get in the way of the stud.

 

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I made just one stud, as a trial, as the best method to make another seven all matching.

 

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I took out this oil supply pipe union, I had forgotten to remove it previously, when I first stripped the engine.

 

I then split the crankcase to remove the flywheels and conrods.

 

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I don't like the look of these bronze or brass filings around this hole. Maybe the nut is slightly too thick and touching the main bearing? I will have to check.

 

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I thought about what JV had said about fitting nuts under the studs. I think it would be rather difficult on this curve and also the closeness of the flywheel.

 

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This amazed me - the amount of oil in this engine with the drip feed lubrication. On my 1910 motorcycle it only needs an egg cup full of oil in the crankcase and one push of the oil pump every 5 to 7 miles.

 

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After taking the crankcase apart I put all the studs and nuts in a bag. I have been doing this with all the other parts. For some unknown reason I seem to have mislaid the original nuts for fitting the jugs to the crankcase!

 

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Back to attempting to get the two halves of the crankshaft/flywheels in line.

 

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This is all becoming rather tedious, although I am determined to get it straight in the end.

 

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That's the way to go. I'm as determined to do as much as I can myself as well but I have the jugs of my car bored by a shop that had the right equipment...I thought about buying it but it was just too expensive for one job.

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