Sunday, 7 June 2015

Humber Speedster Project - Update # 8

I had intended to put up more regular updates, but each time I went to take some photos I thought I’ll just finish this bit first, resulting in nearly a month going past since the last one. As I said in my last update I'm trying to really push along to get Huber` finished for the National Humber Rally next March, so have been hard at it every weekend and have been taking some time off work to get ahead. I had lamented to Svenja that I just don’t seem to be getting stuff done as quickly as I had wanted, but after looking at the photos from the last blog entry a fair bit has been done. As usually with this type of project things get put on then taken off again, changed and refitted. Because I'm building this without a design, except in my head, I tend to do a lot of sketches as I go, tackling each component knowing it has to work as a whole. But it’s very easy to get immersed in the engineering of a particular item and forget! I’ll list what has been done, as shown in the photos.


SUPERCHARGER MANIFOLDS: The last blog showed the inlet manifold completed. The manifold between the S/c and the cylinder head, (which I thought was going to easier!), proved a big headache. It had to be constructed to allow for clearance between the firewall and the S/c, and in the correct position for the chain drive to align, and to allow the bonnet to close over the carby and air filter. All in all a 3D puzzle. I got all the measurements as best I could using my cardboard S/c on strings, held my breath and ordered the plates cut. The day I picked them up I tack welded them together and did a test fitting, my initial measurements were pretty close, but a bit too high, the carby wouldn't fit under the bonnet (hood) – bugger! I knew the space between the steering box and the intake manifold was pretty tight – too tight. I had to cut my completed beautiful manifold ;-(  Oh well them’s the breaks.
Cutting the inlet manifold - it was painful ;-)
Explosion Door  - inside view
External view of the explosion door.
The cardboard & string Supercharger














 Another item I had to incorporate into the discharge manifold design was an ‘explosion door’. My research on ‘draw through’ or ‘induction’ type S/c set ups lead me to an interesting sentence in an article I had read – the supercharger case and manifold now contains a highly flammable gas mixture with a very serious risk of explosion and fire should the engine back-fire, drop a valve etc. Because of this the plenum (manifold) isn't safe as it’s a potential bomb’.  Oh Goodie !  To rectify this situation the article mentioned a ‘positive pressure safety valve’, or bursting disk. From my experience with steam boilers I knew they were fitted with “explosion doors’ in the case of an over fuel situation and possible EXPLOSION!!!!  So by my reckoning if these little suckers stop a boiler from having a bad day they’ll stop Huber from self destruction – which would be nice for all.
The chain drive on the S/c whilst a cool idea was proving a little tricky, apart from it having to be correctly aligned to stop chain wear and possible chain ‘jump off’, it had to be continuously under tension to allow for stretch, (which is common with new chains). Therefore I had to design and fabricate a tensioner device – done. Then I realised the chain came very close, I mean VERY CLOSE to the oil filler cap, so another sprocket is required to give this more clearance – this is yet to be made.

Machining the idler sprocket for the tensioner arm.
The completed chain tensioner
























SPARK PLUG LEAD TUBE: To fit in with the pre 1920’s look I wanted the plug leads to go through a copper tube from near the distributor in front of the head then past each plug. The photo describes this better. Of course I had under ordered the high tension lead by 6” (150 mm). Grrrrrrr so that job couldn't be completed until the extra wire comes in. Did I say Grrrrrrrrr.

THE COOLING SYSTEM:  I mentioned in a previous update that I am using a Davies Craig electric water pump and fan, with their very clever controller which runs the pump and fan individually or in combination to suit what engine running temp you want. When starting cold the controller pulses the pump to allow the engine to warm gradually, then brings in the fan when required – very cool ;-) The reason I'm using this is because the original Humber pump was completely shot, being made from early aluminium alloy and now 83 years old, it crumbles in your hand. I had to fabricate the radiator hose spigots at the cylinder head and block end, fitting the new water pump directly in front of the block. The reason for this location was the configuration for the pump inlet and outlets, this was the least worst look for the installation! The only problem was the back of the pump, being modern and all that, was you could see the wiring, and it just looked plain out of place in a pre 1920’s era car so a copper cover plate fixed that.  Both top and bottom radiator hoses are now fitted and the cooling system is fairly complete. The bottom radiator hose is of Studebaker origin, and was a battle to fit. Who’d of thought Studebaker and Humber radiator hoses weren't interchangeable ;-)

The ugly back of the water pump.

A good view of the right hand side of the engine.
Oh, I nearly forgot to mention I wasn't happy with the internal condition of the engine water ways, especially as I was fitting a brand new (plastic) bodied water pump. I could see some old scale and rust particles through the spigot openings and decided to chemically clean the water galleries – well I do own a water treatment company where one of our services is chemically cleaning heat exchangers, so why not. I'm a lot more confident the new pump and the new radiator core will not have to deal with ‘rocks’ now.
Engine getting an acid clean



IGNITION COIL: Quite a few years ago I bought an unusual ignition coil with a glass bowl, for a curio really, I guessed it was off some unusual orphan car that had long since been forgotten. I’d had it bolted up on my workshop wall but when the Speedster project came along I got it down and started to do some investigation – What was is off? Could I use it on the Humber? After a quick electrical test I found it was still in working order! Another check of the resistance confirmed it was a 6 volt coil. I had read somewhere you could use 6 volt coils on 12 volt systems if you increased the resistance. So after some more research I ordered a 1.5 ohm ballast resister to add to the existing internal 1.5 ohms which will allow it to be used on a 12 volt system (12 volt coils has 3 ohms resistance). Another piece if information I found was it was from a 1950’s Citroen tractor!

The weird coil


I've just started to install the alternator, this will be located between the engine and the radiator on the left hand side – it was either there or driven off the drive shaft under the car. It has to be mounted backwards, with the pulley facing the engine turning anti-clock wise. Which by all accounts is no problem for charging but the fan must be altered to work in that direction and as anti-clock wise fans don’t grow on trees I decided to reposition the blades and see how that goes.

I swear the beer was for cooling the metal !



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