Hallam Engine

[chris stephensParticipant @chrisstephens63393]

Hi Alan,

Two strokes  are notorious for fowling their spark plugs. Take the plug out and while earthing it, trigger the points and see what sort of a spark you get. If it is a bright orange one, or not firing across the the electrodes, your plug is fowled. Give it a good clean and don’t think that because you cleaned it two minutes ago that it hasn’t fowled again. They can fowl in seconds, especially if it is running rich or over oiled.

The ideal colour of spark is bluey-white, I believe that the orange colour is from ionizing the excess oil or petrol vapours. Just because you have a spark, it does not mean it will fire the mixture, it has to be the right sort of spark.

Years of motorcycle two strokes have taught me this. I wont bore you lot with tales of Yamahas so flooded that the exhausts were half full of liquid petrol. It does bring to mind though the thought that if your engine wont start, have you tried turning the engine upside down, and without the spark plug in, turned the prop. If liquid comes out the plug hole it is a sure sign that the crankcase was flooded.

chriStephens 

[CirclipParticipant @circlip]

Does it “Fowl” if you use a chicken stick????

[chris stephensParticipant @chrisstephens63393]

Chicken on the brain I guess, as well as the menu. I’ll let others say “chicken brain”

Ain’t English grand and Yaboo-sucks to my spell checker.

If my spelling is the only thing you can correct me on, I’m a happy bunny.

chriStephens 

[Alan Worland 1Participant @alanworland1]

Thanks Frank but battery fine! Look for the obvious first!

 

I have ‘drained the crankcase’ a couple of times – flooding not major.

I have only had the plug not spark a couple of times and it will give a nice fat whitey/blue spark. It was set to about .025 but I have opened it up a bit, no change though! I was suprised how well it gives a spark with just slow cranking, suggesting that a normal ‘flick’ should start it?

[Martin WParticipant @martinw]

Alan

 

Not sure if it has been covered or not but it could be that the coil is failing. While it gives a good spark at atmospheric pressure when the ambient pressure is increased i.e. in the cylinder at near TDC, the voltage required to generate the spark increases significantly.

 

Stirring me grey matter from 50 or so years ago when points and coil was the standard car ignition I seem to remember that this increase in voltage can cause an ignition coil to fail internally and stop it generating a spark. I believe that this can also be applied to the spark plug itself where the actual spark then doesn’t go across the plug tip but arcs over elsewhere in the body of the plug. Another possibility is that the capacitor might be failing of have a poor electrical contact with the earth of the coil, again a faulty capacitor can cause a loss of spark.

 

Then we had a piece equipment in which you could mount the spark plug and observe the spark gap while increasing the pressure. Frequently it was seen that some coils and plugs we tested would perform brilliantly at atmospheric pressure but quickly lost spark as the pressure increased. 

 

I expect you will have covered much of this in your own investigation and there will be other ideas out there which will be worth looking at.

 

Might be worth while swapping things about if you have some spare bits.

 

 

Cheers

 

Martin W

Edited By Martin W on 10/03/2010 16:26:22

[Alan Worland 1Participant @alanworland1]

Thanks for that Martin, When I initialy ran the engine is was using the coil from my car – aright lashup with many feet of cable – including improvised HT lead!

Since I have been trying to run it again I have been using another coil (also 50 odd years old) and a proper HT lead, and it doesn’t want to know! Could be suspect coil.

I think my next stage will be to repeat the original heath robinson setup!

[Ramon WilsonParticipant @ramonwilson3]

Well after a bit of a delay caused by unforseen factors I finally managed to get some time on this example today with reasonable results……

 

But first a day or two back –

Having bolted the original head back in place the lack of compression and sounds of leaking were apparent. A squirt of fuel showed frothing around the head and the plug seating. There are no gaskets fitted to any joints on this engine. The head was held in soft jaws by the cylinder register and a minimum skim taken across the plug seat. The plug, a ‘Pacy’ was taken apart and the boken insulator repaired with epoxy. (So far no problems with this repair at all). A new copper plug washer was turned and annealed.

The head was then refitted paying real care to the bolting up and the compression improved considerably ( though I still have my doubts over the composite piston’s ability to hold compression as well as one machined from one piece).

 

The cam was set so that with the timing arm in its retarded postion the spark occured just after TDC and a locking arm made from 1/8 brass rod, one end threaded to fit the timing arm and knurled for grip the other. The intake tube and spray bar fitted was the homemade one that had been proven when using glow fuel.

 

The coil – totally unmarked so an ‘unknown quantity’ appeared to deliver a good spark from a 6v supply which also showed I guess that the condensor was also functioning correctly. The let down was the petrol – last years lawn mower from the shed kind – spit pop bang – but no run more than two or three seconds and a worn out shoulder however it was felt the parameters were there.

 

Today however, with new petrol (super unleaded) mixed 4:1 with two stroke oil, another attempt was made. This time the engine showed much more promise and began to fire and run for  a few seconds at a time. These short ‘runs’ were sufficient to see that even with the much finer control with the home made needle valve it is incredibly easy to flood this engine. The plug was checked – oily – and the gap checked, something over looked in eagerness. The 30! thou gap then was quickly reset to 10, the plug cleaned and instant success – it  fired and ran within an armful of flicks.  By manipulating the timing and resetting the needle the revs improved and the engine settled nicely into a reasonably consistant run.

I have no idea of the revs, perhaps 3000 – 4000ish they certainly appeared much lower than anticipated and are not much more than Alan’s engine appears to give. What I was really surprised to find was that the needle in it’s optimum position was open just 1-1/4 turns supporting the comment read that “these type of engines (spark) will run on a mere smell of petrol” (It was some 31/2 turns when using glow fuel)

 

I have had several runs of three – four minutes (have to think of the neighbours) all on a 13 x 5 wooden prop The engine like Alan’s is still new inside and needs to bed in as yet but is not tight anywhere. The timing arm is not critical as such, but does need to be in ‘just the right place’ to give a consistent run and being able to move it whilst running is definitely a requirement.

 

As with trying it on glow it does get hot and begins to hunt a little before dying off slowly (newness perhaps) then it does not like starting until it cools somewhat, however I might try some smaller props perhaps 12 and 11 x 5’s to see if the run smooths out at slightly higher rpm 

 

I did take some video and yes I have managed to get it into the computer however does this have to go on You Tube for anyone to see it or am I able to use Picasa as I do with still pics ( I’ve had a good look on Picasa today – it talks of movies and video but simply can’t see how to get the file on there for others to see – anyone know how to do this?

 

Despite some thoughts I have learnt quite a lot by taking an interest in Alan’s initial posting – it has brought me into contact with others whose opinions have been taken at face value then acted upon to prove right or wrong. By doing that I now feel much more confident in attepting a ‘sparkie’ of my own in the near future which I guess is what its all about.

 

Regards for now – Ramon

 

 

 

 

 

 

 

 

 

[Ramon WilsonParticipant @ramonwilson3]

Hi Alan,

Thanks for the PM. Thought you and possibly others interested would like to see a some pics of the Ohlson and Rice sparkie I mentioned.

 

 

 

 

This was recently given to me by the friend I borrowed the Hallam off. Apart from a very rusty steel cylinder outside the internals appear to be okay. The method of construction is quite unusual – the piston has to be rotated through 90 degrees to remove it through the crankcase front as the liner,fins and head are all one piece and are, I am informed, ‘spot welded’ into the crankcase. The round mark just above the crankcase opening is repeated on the rear and is apparently the ‘plug’ pressed in after welding to ‘finish off’.

There is a heat witness mark clearly visible on the liner inside and I’m told it needs special tooling to replace it if the liner is actually removed.

Unfortunately it is missing it’s timing arm and points so something will have to be made if one can’t be sourced but the rest of it should rebuild nicely – the cylinder heads were evidently lacquered black and, despite the rust, there is some very slight remains of that to confirm it. It will certainly be nice to try and restore it to running condition again.

 

My friend was quite positive about ‘rebuilding the insides’ of the Hallam to see if the running characteristics can be improved but this and this O&R will now have to wait until later in the year though I am trying to get a bit more done on the Racers before the garden takes precedence!

 

Good to hear you are now getting some results yourself on the Hallam and do keep us posted on your new experiences with the Magnum.

 

Regards – Ramon

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

[thomas oliver 2Participant @thomasoliver2]

I have a Hallam 10cc which I made from original castings and have had the same sorts of trouble which you have had.  I found many inaccuracies in the original drawings, and the castings were awful.  I abandoned trying to fettle it years ago, as I found that there was a lot of sub piston induction which should not have been there, even though it is made accurately to plan.  I will eventually be making a new piston slightly longer to cure this. On the earlier two-strokes the pistons all had a deflector  formed on the piston top to deflect the incoming gas upwards towards the top of the cylinder, so the deflector needs to be on the transfer side. This is called loop scavenging.  The separate deflector on the Hallam allows  hand manufacture instead of milling it on.  Few early model engineers had a milling machine.

    I have the plans,  and I can send you a copy if you still need one, and send me your address.  Tom Oliver

[Alan Worland 1Participant @alanworland1]

All these Hallams about! Great to have contact from someone who has built one

Tom, I have pm’d you

Nice little project you have there Ramon, in many ways it seems similar to the Hallam, I think my results were temporary as blisters on my ‘starting hand’ I think will relagate it back to the drawer for a while!

[Ramon WilsonParticipant @ramonwilson3]

Hi Alan and Tom,

 

Seems that these engines if nothing else are consistent in their running properties and bear out their apparent reputation for not being ‘particularly great runners’.

I would be most interested in seeing a copy of the drawings Tom and will send you a PM later.

Interesting to hear of the sub piston induction. A bit late to check it tonight but I’m pretty certain this example does not have any.

 

The time away from this for a few days has seen some progress on the Racers but as said it will be a few weeks before I can get back onto either of these engines.

 

Thanks for your kind offer Tom -be in touch tomorrow

 

Regards – Ramon

 

[Ramon WilsonParticipant @ramonwilson3]

Hi again Tom, PM with address sent.

 

I have just checked the example I have here and that definitely has no sub piston induction though it is very close – the lower edge of the skirt must be within a few thou of the lower edge of the exhaust at TDC.

 

The piston fitted to this has a deflector top as you describe – rather crudely filed on it has to be said so the piston is something I would like to improve on when I do get round to working on it again.

 

Thanks again for your kind offer

 

Regards – Ramon

[p j riordanParticipant @pjriordan89154]

hi i have a hallam model and am looking to find out which one it is hope someone can help

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