Monday, 6 July 2015

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.

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