ME 4761 – Sirius Piston Valve C**k up Corner

[Martin ConnellyParticipant @martinconnelly55370]

This one worked for my Sirius.

Martin C

[Charles LamontParticipant @charleslamont71117]

Dave, I did not criticise or point out drawing errors per-se, but rather the whole concept of the article.

By ‘sanity checking’ I meant that Martin should perhaps have thought to himself (as I did when I read it). “Hang on a mo, thousands and thousands of these things have been made over the best part of a century. Is it actually likely there is a design error?”

“Does this even sound right?” is always a good starting point in a world full of total BS.

[Charles LamontParticipant @charleslamont71117]

I have now been sent the relevant parts of the Sirius drawings, sufficient for a complete study of the valve gear.

I can confirm that there is nothing wrong with the original valve drawing as shown and mistakenly complained about in the article.

It does have lots of exhaust clearance, which I had not expected, but which I can see might well be desirable in such a high-speed engine with a small clearance volume. I will do myself a timing diagram sometime out of interest.

One sensible point in the article is that the little sleeve for properly locating the head on the cylinder really ought to be fitted. If the head is only a few thou out of place it significantly messes up the lead.

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