Super Simplex Valve gear

[DericParticipant @deric]

Evening all,
Some advice please, on the subject of slide valve setting. Everything’s in place and I have checked and double checked, the ride height is set at 13/16”, timing is set at TDC and BDC , it rolls very smoothly with no tight spots. But I’m not sure about the actual slide valve position, I read somewhere a long while ago that Super Simplex should have a lead of 0.020” . Can someone either describe the positioning of the slide valve or point to an article for more details/information.
Help is much appreciated

[DericParticipant @deric]

Slide valve setting

[duncan webster 1Participant @duncanwebster1]

With Walschearts gear the lead is fixed, just set the valve on the spindle so it opens equally at TDC and BDC. If it is actually 0.02, that is lot of lead for a 5"g loco. The only way to reduce it is to either make a new longer valve, or a new combination lever. Clearly the first is easier

[Nigel Graham 2Participant @nigelgraham2]

Just to amplify a little, the lead is set by valve and port dimensions, not valve position; although if that's out of adjustment it will give early admission at one end and late at the other.

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