Edgar Westbury Wallaby ignition

[JasonBModerator @jasonb]

You can get CDI units for two cylinder engines. I have one by S/S though currently not being made and Minimag also have one for two cylinders, saves buying two and less bulky as well.

[Andy CameronParticipant @andycameron27025]

Thanks, i had a look at Minimag and they say that their CDI can be triggered by hall sensor or points so the dual unit for points only at the moment might be perfect. I assume i still need the capacitor across the points with a CDI unit ?.

[Anonymous]

It would be rather pointless (!) using points with a CDI system instead of a Hall effect device. However, if points are used the capacitor is not needed, as the points act as a trigger and do not see the inductive flyback voltage that can cause arcing in a conventional ignition system.

Andrew

[Andy CameronParticipant @andycameron27025]

Agree on it being pointless but its quick to get it running and nice and small then i can add the hall effect sensor later on when i figure out the timing. Not too sure how to wire a CDI to points as a trigger but hopefully instructions are provided

[not done it yetParticipant @notdoneityet]

As I recall, my little box of tricks simply discharged about 3-400V stored on a 1/2 microfarad capacitor via a thyristor/power transistor, triggered by the points. I used my normal rev counter, but apparently on that particular unit the current to the system was linear and peaked at 1A @6000rpm for a four cylinder engine.

The main problem was the inverter ran out of power at high rpm or suffered from poor starting energy – the spark duration was not as long as the ‘ringing’ in the Kettering system. Basically, I needed a better inverter circuit than a couple of BC108/9 transistors and 2N3055 power transistor(s)… but it was far better than the Kettering system most of the time. There were, I believe, one (or two) switches on the unit which could be flicked over to change between the electronic or Kettering system. Electronics have moved on since the early 1970s, so modern ones should give no trouble with a slow(ish) revving engine.

[JasonBModerator @jasonb]

The unit may be small but a set of points on a model of that size are very cumbersome. Most CDI ignitions can be triggered by just a contact which is what I use most of the time which is small, discrete and in many cases can be made as per the full size contacts. I've only used hall sensors on two of 15+ spark ignition IC engines that I have built.

It's also a lot easier to arrange for one of the contact points to be movable while the engine is running so you can advance and retard the timing

On the CDIs that I use you just make use of two out of the three wires that would go to the hall sensor. Looks like Minimag is the same may need to alter the cam (or at least it's position)that actuates the points as the CDI fires when contacts are closed

 

 

Edited By JasonB on 20/09/2022 07:18:42

[Andy CameronParticipant @andycameron27025]

Ok your last line is something i will check on with Minimag. Now to a more mechanical head scratcher, i am awaiting some info from the previous owner but while i do i have some thinking to do regarding the cooling setup. The engine mounted on a board and there is a large brass tank which is taller than the engine, there is a pipe coming from the bottom of the tank to the bottom of the crankcase and another pipe from the top of the tank to the cyclinder head. No pump etc. The pipe from the top of the tank connects through the tank and there is a pipe inside the tank with slits cut. I guess this could be a simple sprey allowing the water to drop down and cool back to the top of the water level ? that might make sense but how the water gets around the engine and up to the top of tank is a puzzle as there is no pump. I could get water into the engine just by the level of the tank but how it circulates is a mystery as im not aware the wallaby has a water pump only oil. Anyone seen a similar setup ? when i can figure things out i will post a photo.

[JasonBModerator @jasonb]

Thermo syphon is what makes the water move, as the engine heats up what is in the cooling cavities the hot water rises and draws in cooler water from the bottom of the tank.

I doubt you will get much of a head to lift the water in the return pipe above the level in the tank so best to fill it upto the return pipe or a bit above

[Andy CameronParticipant @andycameron27025]

Thankyou….some real physics at work. For now what i have been doing on the Gannet with water jacket is manually pumping water with a garden pressure bottle 5L. This sounds very interesting so will give it ago and see what happens. Once i have tested all is well i will probably get a chinese kit with radiator etc.

[not done it yetParticipant @notdoneityet]

JB,

I’m not understanding your comment re water level. The thermo-syphon system ideally requires a closed loop of coolant such that the inlet side of the radiator is hotter than the water percolating through the radiator, cooling as it goes. The difference in density between the engine outlet (hotter) will be less dense than that in the radiator (at the same level), so will rise in the inlet pipe. Practically the effective temperature/density difference will be much extended towards the lower parts of the engine.

The problem arises with water (cooling) distribution around multi-cylinder engines. There is little trouble with single cylinder engines without a water pump.

Some single cylinder barn engines simply used a large tank as as a cooling radiator and some had a cooling fan – when less coolant and a tubed & finned radiator was employed. Some then utilised a separate water pump, but usually combined with at least the same drive belt as the fan.

Earlier single cylinder barn engines simply employed a hopper above the cylinder head and relied on evaporative cooling ie needing regular top-ups as the water boiled away – if the engine was working hard. Not many stationary engines at rallies/shows are actually run hard these days, of course, often not even to the boiling point.

Even some multi-cylinder engines with pumped circulation used to suffer from scale build up at the rear of the engine. I’ve knocked out cylinder liners which have been almost completely devoid of any cooling, due to being virtually encased in lime scale deposits (I expect owners drained their engines in frosty weather and re-filled with temporary hard water – often not from the cleanest of supply, either).

[JasonBModerator @jasonb]

My comment about water level was that I doubt there will be much chance of the water being lifted above the level in the tank to provide the "spray effect" that the OP mentions.

Most tank cooled engines and the models of them that I have made have the level in the tank at about the same level as the return pipe as you would really need the water bubbling and boiling to lift it to any head difference.

I was just explaining how the tank was intended to work and how a flow developes, as you say the passages in this engine may not allow for a good flow unlike the typical single cylinder engines that have a wrap around water jacket with few restrictions. It may well need a pump adding and maybe a better means of dissipating heat than a plain tank which will depend on length and speed of runs and if under any load. The reason the tanks are often tall or mounted on legs is to encourage a flow of water in the vertical or sloping pipe as it exits the engine

The other popular method with the open crank engines was to pump the water through a spray bar or head and onto a wire screen above an open tank which increased the area for cooling the water, I've done a couple of models with this, both used pumps, one belted off the crankshaft the other with a piston type pump similar to a loco axle pump.

[JasonBModerator @jasonb]

Talking of loco axle pumps, does anyone know how Westbury arranged the cooling in 1831 that the engine was intended to power?

[Andy CameronParticipant @andycameron27025]

i dont think the cooling setup is good so i will be looking at adding a pump to force circulate the coolant. i will give it a brief run 30secs un-cooled. i would love to stick this in a 3 1/2 loco radio controlled.

[Andy CameronParticipant @andycameron27025]

I have checked with Minimag and their dual output CDI unit will trigger when the points open so thats good. Whats the general opinion on suitable oil for such an engine, i believe the spec was originally SAE30. I have some Castrol 10W-30 lawnmower oil for 4 stroke use, which i think would be ok or should i stick with just SAE30 ?

[Andy CameronParticipant @andycameron27025]

I am thinking that as being in the UK and the small size of the oil pipes pump etc that 10W-30 might be the better choice for initial cold starting.

[duncan webster 1Participant @duncanwebster1]

Old Fordson TVO tractors had a semi evaporative cooling system, they worked best when they were at or near boiling, and had a big oval filler so you could fill them up from a bucket. fordson

When I were a youth I earned money to buy first motor bike by haytiming on farms in Yorkshire Dales. They only needed one tractor most of the year, but at haytime old wrecks would be dragged out to increase the fleet, so I've been paid to drive tractors older than me. The spring seat took some getting used to, try using clutch/brake when you're bouncing up and down over a rough field

[not done it yetParticipant @notdoneityet]

Duncan,

That is how I financed running my little Honda 50 sprint (the proper motorcycle variant). I did buy it beforehand, but cannot remember how the purchase was financed!

You can see, from that video you posted, that those tractors used a radiator for cooling. Yes, they did often boil when working hard – but for that ploughing he only had the radiator blind part way up.

Those old Fordsons needed heating up well, before turning from petrol (for starting) to TVO, so the blind was quite a necessity. TVO was far cheaper than petrol!

There were tractors with better heat transfer to the manifold than the Fordson Standard. I can start my 7 1/4 litre tractor with less than 1 litre of petrol, before changing to kerosene. The old Fordson popped and banged for ages before it was hot enough to run on TVO – and if it stopped it was often trouble to restart!

[duncan webster 1Participant @duncanwebster1]

I know they had a radiator, but not pressurised, so at running temp when working hard haymaking in summer, the water evaporated and had to be topped up fairly frequently. If it was cold you might have to blank the radiator to get it hot. They didn't pull well when cold, or perhaps it was just the one I was lumbered with. The grey fergie was much nicer, and the MF 135? was even better. I never got a go at the Fordson major, that was reserved for the baler, and that was the gaffer's domain

[not done it yetParticipant @notdoneityet]

The ‘sit-up-and-beg’ EN27 fordson major had the same engine as the earlier standard fordson. Ours was gutless, likely due to the gearing and lack of horse power. I think you may be referring to the later EN1A, which was the petrol version of the much popular diesel variant?

[duncan webster 1Participant @duncanwebster1]

It's nearly 60 years ago, I've no idea what the model number was, probably didn't know back then. Petrol/tvo, hand crank to start, cast iron header tank to radiator and a very bouncy seat mounted on a leaf spring is all I remember.

We had the same/similar engines in some railway locos on the R&ER, made by Muir Hill. Horrible to start as the side frames restricted access to the winding handle. One of them is in the museum, not sure if it can still be run, at one point it had con rod sticking out of crank case, but there was a move afoot to find a replacement engine. I remember that the loco version had a multiplate steel on steel clutch. No oil pump, it relied on splash with dipper tubes on the big end caps.

[Tim StevensParticipant @timstevens64731]

A few comments:

The coil for use with a Kettering* battery system is not the same as one for capacitor discharge. The proportions of the two windings are quite different, as is (usually) the design of the magnetic circuit. So, when buying a coil you need to say which sort of coil, as well as single or twin output.

Single output coils can be used on a twin with a crank-speed contact-breaker – the idle spark has no real effect on plug-life, or electric consumption. They also work on a V-twin, but you need a contact cam at camshaft speed and with two lumps to match the angle of the engine.

The idea of a six-volt coil on a 12v system using a resistor to knock the voltage down, was used mainly on big cars which were not always good starters. there was an extra contact in the starter solenoid that shorted out the resistance when the starter was operating – compensating for the reduction in battery voltage as the starter drew 200 amps or so. And relying on the fact that the boost to the coil was only for a few seconds so overheating was not a problem. Some systems also used a resistor which as it warmed up in use, increased its resistance. So, you got a boosted spark at start-up, and less drain on the battery as the engine warmed to running temp (and so needed less biff in the spark).

* Kettering ignition is the proper name for what is often called 'coil ignition' or battery and coil ignition'. Confusion can be caused as almost all ignition systems have coils, and almost all vehicles have batteries too. Kettering was the Chief Elecric Engineer for the DELCO company in the USA, and his work led to the eventual abandonment of magnetos – especially (you guessed!) in American cars – starting about 1912.

Cheers, Tim

[Andy CameronParticipant @andycameron27025]

latest, firstly does anyone know where i can get a drill dog bone drill starter attachment for larger engines. The usual ones i see on ebay are too small. Currently i have been using a small drill chuck key which is quite a good fit but could be better. Quick update:-

Minimag dual ignition CDI setup and working. Good spark and timing looks good.

Will it start NO. I think it did fire briefly for about 2 seconds but since then nothing.

Fuel is getting to the carb and even squirted some directly in. Still nothing. The time i think it did fire i used a 12v RC IC engine twist starter which gives a much faster spin than an electric drill so wondering if it needs a fast spin up.

Using 97 octane E5 fuel with redex added, i use this on my Gannet engine which works fine.

Checked one plug which appeared a bit wet after spinning it up with finger over carb. If i can get a better starter arrangement i will try again. Any info on dog bone starter or experience with these engine would be much appreciated.

[Andy CameronParticipant @andycameron27025]

In addition, i should have mentioned that if i spin the engine continuously with the throttle closed it spins easily and as i open the throttle the compression seems to increase.

[Andy CameronParticipant @andycameron27025]

I decided to drop the oil out, its hard to tell but the oil does smell a bit petrol so i wonder if i need to strip it down and check the gaskets everywhere. Although im sure how fuel would make it into sump ? so maybe its just the way the oil smells.

[JasonBModerator @jasonb]

If you flood it enough the fuel will get past the ring gaps. I usually find most model engines only need the needle valve opening a very small amount as the mixture soon gets too rich

I don't use a drill much for starting but made my own drive dog arrangement when I did need it. I either just flick the flywheels over by hand, use a short pull cord or a starting handle.

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