Simpson and Shipton engine

[Jeff DaymanParticipant @jeffdayman43397]

I emailed Stewart about a possible drawing error on the Simpson and Shipton engine piston. He emailed back that the 15 mm dia hole shown on the piston drawing in ME 4437 is a mistake, it should not be there. It was a holdover from the original PTFE piston design which is no longer used.

The piston as shown in photos in ME 4439 has no 15 mm dia hole and is shown correctly there.

Hopefully no one has got this far with the engine and drilled the 15 mm hole yet. If they have, the hole could be plugged with a solid piece of CI secured with press fit, loctite or silver solder, or two plugs could be fitted at ends of the hole.

(In ME 4437 the drawing shows the gland packing trepanned groove crossing the 15 mm hole and the 8 mm
hole. When I first saw it, I remember thinking the gland packing would fall
into the 15 mm hole and sealing would be lost, but since the text describing
the piston was to follow in the next article, I figured details of loctited
or brazed or pressed plugs in the ends of the 15 mm hole would follow, or a similar
method.)

JD

[Jeff DaymanParticipant @jeffdayman43397]

[Stewart HartParticipant @stewarthart90345]

Thanks for the update Jeff

I hope my mistake didn't cause any one problems.

Stew

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