Author Topic: Alyn Foundry Sphinx  (Read 8605 times)

Offline Alyn Foundry

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Re: Alyn Foundry Sphinx
« Reply #90 on: October 16, 2019, 06:47:40 PM »
Hi Ray.

Hmmm, this rings a bell!

Try removing the cage and putting an " O " ring to act as a seal between the faces of the Brass and cast Iron body. I'm pretty sure I had the same problem when tightening the two together, slight distortion occurred causing the valve to leak.

Cheers Graham.

Offline RayW

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Re: Alyn Foundry Sphinx
« Reply #91 on: October 17, 2019, 02:25:17 PM »
Thanks for the suggestion Graham. Definitely worth a try, but the thread on the valve cage is quite free fitting in the manifold casting, so I don't think the cage is distorting when I tighten it. I have lapped the valve in some more today, but then discovered that air was leaking past one of the cylinder head studs, so I took the head off and sealed with silicone gasket sealant. Once that has dried fully, I can carry on fiddling with the inlet valve. What I really need is some sort of dye to see exactly where air is getting past the valve head.
Ray

Offline RayW

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Re: Alyn Foundry Sphinx
« Reply #92 on: October 19, 2019, 02:57:02 PM »
Having successfully sorted out the air leak past one of the cylinder head studs, I became aware of another one between the cylinder head and the main water jacket casting. In theory, it should be impossible for air to get into this gap, however large, as the gasket which sits in the cylinder head recess should completely seal the combustion chamber (apart from the inlet/exhaust port) once the cylinder head is tightly bolted down.
After much trial and error with various gaskets, sealant, etc to no avail, I finally discovered the cause of the problem.
When I machined the recess in the head for the cylinder liner flange, I just broke into the outer part of the port, as a result of which there was nothing to support the gasket in that area. The port opening also extended a little way up the side of the recess. The result of this was to expose a small gap above the gaskets, allowing air to escape between the recess wall and the outer rim of the cylinder liner.
I am now modifying the shape of the port with JB Weld to block the gap, and will probably fit a very thin aluminium ring in the recess to provide support for the gasket(s). I did consider reducing the depth of the recess by inserting a tight fitting ring of sufficient thickness to cover the gap, but that would involve making new, longer head studs to compensate, so I will try the JB Weld solution first and see how that works..
Ray

Offline Admiral_dk

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Re: Alyn Foundry Sphinx
« Reply #93 on: October 19, 2019, 07:19:19 PM »
If it was me, I think I would have hard-soldered a hard plug into the hole and drilled it again  :thinking:
That way you should not get any temperature issues + you haven't got any epoxy etc. polluting the area if you need to solder it later ....

That said - others have had success with using JB Weld in hot areas - so it's probably just me being a bit paranoid here.

Best wishes

Per

Offline Alyn Foundry

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Re: Alyn Foundry Sphinx.
« Reply #94 on: October 20, 2019, 11:42:01 AM »
Hi Ray.

Damn, that's unfortunate!

I'm not sure if it's too late but I'd suggest either hard solder like Per has suggested or even an interference fitting plug. You'd have to be sure that it didn't crack the casting however.

Cheers Graham.

PS. I'm unfamiliar with the capabilities of JB weld as I've never used it.

Offline RayW

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Re: Alyn Foundry Sphinx
« Reply #95 on: October 20, 2019, 05:25:17 PM »
Hi Per and Graham.
I have used JB  Weld in similar situations before with no problem. I have built up the port slightly and made up a thin aluminium ring to sit in the head recess. I have sandwiched it between two thin paper type gaskets and stuck them all together with silicone sealant. These modifications have pushed the cylinder head out slightly leaving a gap between the cylinder head and the water jacket which I have filled with a suitable o-ring.
The result of all this is that I now have such good compression that it takes some effort  to turn the flywheel past compression and there is quite strong bounce back.
Ray

Offline Admiral_dk

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Re: Alyn Foundry Sphinx
« Reply #96 on: October 20, 2019, 08:01:15 PM »
Nice to hear that your fix, worked out as planned  :cheers:

Offline Alyn Foundry

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Re: Alyn Foundry Sphinx
« Reply #97 on: October 20, 2019, 09:01:05 PM »
 :)

Offline RayW

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Re: Alyn Foundry Sphinx
« Reply #98 on: October 27, 2019, 02:21:01 PM »
I have been playing around with the ignition system today and thought I had come up with a really neat solution. I made a Tufnol disc with a brass insert as per drawing and a contact unit, again of Tufnol and brass as per the attached photos.
I hooked up a Model T Ford trembler (buzz) coil and a 12 volt battery and that is where the fun began. With the contacts touching each other, all was well, with the coil buzzing strongly and a good spark at the plug.
As soon as I moved the contacts apart however, I got massive arcing from the contact unit to any available point on the engine body, causing the coil to continue buzzing as the arcs maintained the circuit. Arcs were jumping more than 1/4" from the brass hex nuts, and from the contact tip to the nearby main bearing cap, resulting in a burnt track across the surface of the Tufnol.
I know that these coils will run on anything from 6 to 12 volts, so would I cure the arcing problem by reducing to 6 volts, or do I need a resistor or something somewhere in the circuit?
Also, does it matter whether it is the live or neutral lead that goes to the contacts? Both work, although the spark is weaker one way than the other. I am sure all of you electronics wizards out there will be able to offer words of wisdom.
Photo 1 shows some of the arcing.
 
Ray

Offline Jasonb

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Re: Alyn Foundry Sphinx
« Reply #99 on: October 27, 2019, 02:33:50 PM »
Positive to the isolated contact and negative to the engine frame. have you got a capacitor (condensor) in there anywhere? 6V will do, the small sealed rechargables are OK.

Don't really use the old style stuff these days just a simple contact to switch the low current CDI and ether a single spark or buzz unit.


Offline Alyn Foundry

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Re: Alyn Foundry Sphinx
« Reply #100 on: October 27, 2019, 03:16:01 PM »
Hi Ray.

You're getting closer now!

I'd be inclined to use 6 Volts personally, as I've explained several times that the Trembler box was never intended to be run from a Direct current source originally. ( Model T application )

Try a solid, via on off switch, Positive to the trembler box and place the Negative ( and also the ground side of the HT )  of  the trembler box to the engine frame. Take the negative from the battery to your insulated terminal adjacent to the bearing cap. I think this will cure the HT arcing problem for you.

Cheers Graham.

Offline Jasonb

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Re: Alyn Foundry Sphinx
« Reply #101 on: October 27, 2019, 04:11:38 PM »
This is how I have wired them in the past

Offline RayW

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Re: Alyn Foundry Sphinx
« Reply #102 on: October 27, 2019, 04:56:39 PM »
Thanks Jason and Graham. I did try a 9 volt battery, but with same arcing problem as 12 volts. I will get a 6 volt rechargeable one and try that.
Not sure what you mean, Graham, by "Try a solid, via on off switch, Positive to the trembler box". Could you explain please. Thanks
I must admit that the old trembler coil is a bit too bulky really, so I may well end up getting something smaller. Do you have any recommendations?
Ray

Offline Jasonb

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Re: Alyn Foundry Sphinx
« Reply #103 on: October 27, 2019, 05:24:21 PM »
Engineer's Emporium sell just the trembler points which you can make your own buzz box from with the addition of a small ATV coil and a lawnmower condenser. This will fit into a box about 3" x 3" x 4" with room for a small 6V battery too.

Here is one I made earlier



Plug with red & black wires if for charging




Alternative is one from S/S which can either be tripped by a hall sensor or two simple contacts which is what I mostly use. look at the "multi spark buzz coil CDI"

http://www.cncengines.com/ic.html

Offline Alyn Foundry

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Re: Alyn Foundry Sphinx
« Reply #104 on: October 27, 2019, 05:49:26 PM »
Hi Ray.

Well, thanks to Jason you have your answer, the drawing.

The Positive is going directly to the Trembler box. An on/off switch is not absolutely necessary but can be useful in an emergency situation.

You will notice that it's the Negative side that is " making/breaking " the circuit. Because both the HT and LT coil windings are " joined together " internally at the " ground/earthy " side, so when this is directly connected to the engine frame it ensures the high voltage stays across the sparkplug terminals.

Cheers Graham.