Valve setting on Martin Evans Highlander

[palmcoast]

Hi. Having got my Highlander to the point of setting the valves and , hopefully, running it on air, I cannot find any information in the ME build series on how to set the valves! Does anyone have any information on this please. Tom.

[donashton]

Maybe you should read a recent thread on page 2 'setting walschaerts' gear' so that you can be more specific.

Don.

[donashton]

Sometimes the drawing includes a section through the cylinder bores to show piston and valve. If Martin hasn’t done this for Highlander you can do it yourself and learn about setting. Either with pencil and paper or the real valve do the following.

Draw the valve, ie. the two bobbins with the middle bit joining them. Note the following dimensions:
Total valve length, width of each bobbin (usually both the same).
We now need to add the ports, with the valve sat centrally, and we can see that the outer edges of the bobbins coincide with the outer port edges. As the steam comes from between the bobbins it should be obvious that it cannot enter either port without moving left or right from its central position. What is more, we know by how much – subtract the port width from bobbin width.

But how can we ascertain when the real valve is central over the ports? By measuring from the front face of the liner to the outer port edge, and if we now set the real valve to this same depth inside the bore we call this depth a DATUM.

So by setting the valve depth to Datum + valve overlap (bobbin minus port) we know that the valve will be just about to let steam into the back port. At this point the piston must also be fully back in the bore, ie. on back dead centre.

Now for real – you must find the dead centres so that the wheels can be rotated quickly and accurately to either dead centre, and the above exercise on paper used to place the valve such that both ends the same thing is happening or about to.

Finding dead centres accurately has been described many times, but if you don’t know, ask.

Don.

[jma1009]

wishing not to treed on Don's illustrious toes,

you need to provide us with what stage of setting the valves you require assistance? plus whether piston valves or slide valves? i cant remember offhand without checking if there was a slide valve alternative for Highlander.

is it just setting the valve heads on the bobbin? this is pretty straightforward but time consuming, as Don describes.

or it is setting the valves (ie correct length for eccentric rods/setting of return crank)?

cheers,
julian

[donashton]

Thanks Julian, but my toes are the same as everyone's, save perhaps that treading on them cannot offend.

The major part of valve setting is not done by peeping into dark corners - it is done by seeing the relationship between the valve and the ports on the drawings. Assuming that the design is correct (!) , simply setting the valve roughly by eye such that the port is about to open at dead centre (again guessed by eye) will have any engine running. If it doesn't, the fault is not sloppy valve setting.

Don.

[palmcoast]

Thanks to you both for your comments, Don, your explanation is really what I needed!. Martin Evans did state that the Highlander design was not intended for the beginner, but like others of my ilk, i` rushed in... so now to sit quietly in the workshop and sort it all out. Many thanks, Tom