Humber Speedster Project - Update # 11

The last sentence in my previous Blog entry was, 'The next job is fitting the sheet metal skin – Yikes!’. Well like most of my well laid plans it didn’t quite go according to plan. What seems to happen is that I intend to start a certain project but get side tracked and do something else, which doesn’t really worry me as it all has to be done sooner or later. While I was waiting to have the 15 mm lip folded on the sheet metal side panels by a sheet metal shop, (I was going to do them myself until I found my folder was too short and I couldn’t slide them in from the side). I started to plan the fuel tank cradle and trunk, I had not given this much thought up until now as my main concern was getting the front of the car planned and started. But after sitting beside Hubert and seriously thinking about the look of the back end of the car would really have an impact on the overall look. Maybe this is why a lot of pre- 1920’s cars I looked at have an awkward look about them in the rear section, like the builders realised, like I did, ‘damn, we really didn’t think this through, what do we do now?’ In the initial planning stages I had briefly thought of a boat tail end, but on investigation it was a LOT of work, so decided on a basic exposed fuel tank and attached trunk.  OK, back to me sitting beside Hubert wondering what was I going to do??? This was the time I took a leaf out of Svenja’s book and ‘let it speak to me’, which is an tenet she uses when designing her wondrous costumes.  A trip to the hardware to check out what timber I had to play with and what would suit. I guess the sight of me standing there with a sheet of paper in hand and a thoughtful look on my face it was inevitable I was going to be approached by one of the helpful staff.  ‘Can I be of service?’ asked a fresh faced young lady, I hesitated just for a millisecond about whether I should ask her if the sheet on ply I was looking at would be suitable for skinning the trunk of a 1916 Humber Speedster…… but decided to say, ‘no thanks, I’m OK’.

While I was perusing all the different timber products I formed a plan… yes another one ;-)  I’d use form ply for the structural parts, sides and supports then pine boards for the floor, topped off with a plywood top cover.

Making up as I go along

Trunk ready for skinning

A trial fit for of the ply wood skin.

The fuel tank cradle was fairly straight forward, the shape and size dictated by the tank side, (a re-purposed automotive LPG tank). The sides of the trunk took some design time with my co-designer Svenja with her talent at drawing curves she soon had the drop away to the rear of the chassis sorted. I had decided to make the floor out of 19 mm (3/4”) solid pine in various widths with the edges cut at angles to follow the contour of the chassis and give a sealed surface, much like barrel staves. It was then onto the ply wood ‘skin’, this had to curve to follow the drop away, so it was ‘Kerfed’. This entails numerous saw cuts made across the grain to a depth just under the outer layer which allows the timber to be bent. Getting the depth and the distance between cuts is important to allow the timber to bend freely but not to crack or show creases. This process works well but also removes a lot of the integral strength of the ply wood sheet so extra supports had to be added to compensate. 

 

Liam with the top skin.

Kerfing detail

 

Access to the trunk was also added by cutting the door hole which is supported internally at the edges by form ply braces, the lid will come later.

In between waiting for the glue to dry on the trunk floor the dash board was mocked up using a piece of ply wood scrap the same thickness as the finished piece. 
 

The mocked up dash

 

Steering column bracing

 This wasn’t just a matter of sticking a piece of ply up in the scuttle opening, the recess and angle of the dash plus the position of the gauges had to be set to suit the eye line of the driver. This done, along with welding the mounting tags to the scuttle frame, the gauge positions were measured and noted so a holes can be cut in the final ply wood dash after lacquering.

Well that’s about where I’m up to at present, I should cover the sheet metal fixing in the next blog entry – hopefully !

Humber Speedster Project - Update # 10

I signed off my last blog update saying that this one may include a video of Hubert waking up after some 40+ years asleep. I am very happy to confirm Hubert did wake up and the video below shows the exciting event. The initial start-up took several days to happen after getting the timing right and sorting out some other small electrical issues, then with some coaxing he roared to life, (a wheeze really). The glass ignition coil that I wanted to use wouldn’t play nice on the day, although it tested out OK ?? So I replaced it with a modern type I had on the shelf to keep the start-up on track, (I’ll look in to that other coil later as I’d still like to use it for the look). My concerns about the oil pressure were unfounded as it ran at a respectable 30 psi.

     

    

I ran the engine several times to try and bed everything in after the rebuild, albeit some 14 years after! But as you can see from the second video he ran well. The engine now proven I put it back to bed and started on the body skeleton, after being side tracked by relining the brake, clutch and accelerator pedals with sections form an old tyre I had lying about. (I figured I’d do this before I refitted the floor to allow more working space).










After the floor and toe board were refitted I sat on a stool beside Hubert for quite while forming a plan of attack, (I’ve mentioned in previous blog updates that building this body from scratch was a daunting task and took me well out of my comfort zone), I couldn’t put it off any longer so with sketches in hand I took a deep breath and dived right in.

Floor & toe board refitted.

Relined control pedals

The body frame start point    

Scuttle bow template.

The starting point was obvious – the fire wall, so a template was made and the hammering began. My roller was too small to handle the ½” diameter round bar so it was bent into shape the old fashioned way with a hammer and vice jaws open about 150 mm (6”). The process works by striking the material being bent in the middle between the jaws, this causes a slight or heavy kink (depending on how hard you hit it), in the metal creating a bend. It is a tedious job especially if you are bending it to a set curve, sometimes having to flatten out a kink which an over-zealous hammer strike caused. (not that I ever did that….well maybe a couple of times… ;-)  After a few thousand hits you get pretty good at judging the force of the blow you need, and it does form a curve quite efficiently.

Cold bending

The part of the body from the firewall back to the dashboard or under the windscreen is called the ‘scuttle’. From my research it’s called this as it resembles a coal scuttle, or from a part of the ship called a scuttle, anyway I think you know the part I mean.  I formed this by making another bow with the same curve as on the firewall but 50 mm (2”) higher, this gives the rake from the windscreen down towards the bonnet (hood). To get the correct rake I enlisted a few of my work mates and Svenja to look at some drawings and we all agreed that 50 mm was just right. The firewall bow and scuttle bow (for want of a better name), were joined together with straight lengths of ½” bar welded in place, it was finally starting to take shape.                                                                       

Scuttle completed.

Next was what you would call the body 'tub' - the sides and curved pieces that went behind the seat. The curve for the entry openings, (remember Hubert has no doors), was needed so I called on the resident artist, Svenja to give me a curve to work to. I enticed her up to the shed with a promise of a beer and explained what I wanted, she asked me to put a piece of card board across the gap between the seat edge and the scuttle, then with a flick of the wrist drew the ideal curve. (I would have tried to plot it out with reference points, and taken hours!) It was a case of Artist Vs Engineer, and the artist had the goods on the day ;-) I thanked her for her lovely curve, rewarded her with the aforesaid beer then set about to hammer out the curve. The second one was way harder even using the same template getting it as close to the original as possible, but in the end it turned out pretty close.  With the seat frame four curved pieces were needed, two upper and two on the floor. Because these all had to follow the same curve around the back of the seat I decided to make it a bit easier by cutting out a wooden template and using heat to shape them. This certainly saved a lot of time and made reproducing the curves more accurate.

With the bottoms ones finished and in place the seat was reinstalled, (I’d removed it while welding close by on the scuttle to protect it from sparks), Cold bending the top frame to follow the contours of the seat was difficult – sort of a 3D jigsaw puzzle, without a picture to go by! But after considerable perseverance it took shape, assembling the pieces began and it all came together surprising well - another test with the seat in place proved it was all within tolerances, so the support bars were added. 

Svenja's curve.

Perfect fit!

Rear of tub secured to floor.

Current status of body skeleton.

The next job is fitting the sheet metal skin – Yikes!

Humber Speedster Project - Update #9

Since the last update on June 7th the alternator mounting/adjusting carriage has been completed, which once again turned out to be more involved that I first thought. – this whole project seems to be an exercise of two steps forward and ½ a step back ;-) Due to the close proximity of the alternator pulley to the crankshaft pulley I had to use a ‘link’ type Vee belt to get it short enough. This then presented another problem of how to get enough adjustment as link belts stretch more than conventional one piece Vee belts. This was accomplished by making the alternator carriage in a saddle shape that slides along the old radiator cross member that is now unused after relocating the radiator 150 mm (6”) forward. So with the carriage having 40 mm travel, (which is secured via a bolt through the cross member), and a curved slotted arm with another 40 mm the alternator has ample adjustment. I realised just as I was ready to install it was now that the pulley would be running anti-clockwise it should have some type if locking device to stop the nut unscrewing itself.

Alternator Carriage Assembly

Alternator in situ with link belt

  

Alternator pulley with nut lock tabs in place

I want to ensure the engine runs so I've put off work on the body until I can test it. While I was completing the supercharger manifold I decided to do the initial start-up with a standard carburettor and manifold, which I knew would work so not create any more possible problems. This also meant I had to fabricate a manifold and find a suitable carburettor. I had several old Studebaker carburettors lying around so that was the easy part, the manifold was another story - fairly straight forward but another job to add to the list. When I did finished it I noticed that with the intake tubes on and upward angle they fouled on the side of the carburettor – damn! I must have strong words with the design department ;-) Packer plates, which we’ll call thermal barriers and were intended all along, will fix that ;-)

The unfinished non-supercharged intake manifold.

The next job on the list was to stabilise the starter motor. When I first got the Humber I noticed a crack on the alloy bell housing where the starter motor fits into. There was evidence of previous welding repairs where this had cracked before. It truly surprised me that with the usual engineering overkill Mr. Humber had used everywhere else this looked like an obvious design fault. The starter motor weighs approximately 14 kg (30 lbs), and is secured to the engine by sliding 100 mm (4”) of its 470 mm (15"), length into a hole, then locked in with a tapered bolt. This overhang combined with its weight puts a lot of stress on the alloy bell housing, even at rest, let alone if it hit a sizable pot hole while driving. I had the crack welded, and decided to fabricate a support bracket off the gearbox to be on the safe side.

Starter motor with support bracket in place.

Hubert The Humber totally naked!

 

To get better access to the gearbox and starter motor I removed the firewall and floor, the poor old Humber looked like it did when I first got it, pretty sad, but you have break eggs to make omelettes. While I had access to all sides of the engine I gave it a repaint as I couldn’t get the same shade of blue it was originally painted and adding the bits I was making in a lighter shade looked a bit odd. For some reason I had it in my head that the gearbox had been rebuilt like the engine and differential, but when I noticed a lot of old grease on the bottom I thought I’d better drain it and check it out. What came out when I unscrewed the drain plug horrified me, firstly about half a cup of water, then toffee coloured sludge…   I removed the oil pan to find an inch of oily sludge I guess this is what you get when water and oil mix for 40+ years. I flushed the box out with diesel and have since sealed it back up and filled with fresh oil.

A lovely 40 year old sludge

The gears were in pretty good shape despite the sludge buildup.

 Because the engine has been sitting for 14 years since being rebuilt I was concerned that there would be little if any lubrication left on the metal to metal surfaces, especially the crankshaft and camshaft bearings. With the modern V8 engines I have previously worked on you can pre-lube the system by spinning the engine oil pump with a long shaft and a drill. Unfortunately the oil pump on the Humber is inaccessible in the sump so I thought I’d try and draw oil up through the external fitting that feeds the valve rocker shaft, oil pressure gauge and filter. I was using a peristaltic pump that I use to empty differentials and gear boxes that don’t have drain plugs – peri' pumps are normally used in water treatment to dose chemicals into cooling towers.

The peri pump in place oiling the system.

Anyway after the hose to the rocker shaft blew off I figured there was a blockage ;-)  Actually there was a series of blockages; the gallery from the external fitting to the rocker shaft riser with old congealed oil & whoever reassembled the rockers and shaft had no idea what there were doing!! The rocker shaft is hollow with small holes drilled in regular intervals to align with holes in the rockers, this allows the pressurised oil out to the lubricate metal to metal surfaces. None of the holes aligned.  So if the oil flow hadn't been tested the rocker shaft and rockers would have seized and been destroyed in quite a short time. Trying the save the crank bearings had other unforseen benefits.

Wire failed, so I hydraulically forced it out using a bolt and acetone.

Got it third go, then flushed it with oil

The inlet valve rocker assembly

With the new spark plug leads having a plastic covering over the cotton braid I was concerned about it melting or discolouring being so close to the exhaust manifold. My initial idea was to wrap the manifold in woven insulation tape to keep the heat away from the plug leads, bit it was just too difficult because of the shape of the manifold. I ended up just wrapping the engine pipe that bolts onto the manifold, and making up a sheet metal shield to deflect the heat from the manifold itself.

The relatively simple job of refitting the side cover and rocker cover was delayed when I decided they needed to be re-polished and coated in a clear sealer. I never cease to amaze myself in finding new jobs to do, even though I'm on a deadline ;-)

The heat shield and insulation wrapping in place.

Well that's all for now, hopefully the next update will include a video of Hubert waking up from his extended slumber.