Clevtrev, my drawing ,posted here on the 16th of December clearly says 9/16" x 20 CEI. Surely Vincents would not have changed this half mat through production?
Phelps.
Cylinder Stud Thread Profile
- Thread starter ogrilp400
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Phelps.
To summarize what I think I have learned; Laurie Binns thought the original items were Whitworth form 55 degrees, which the photograph on Page 1 seems to confirm.However, in Laurie's tools are 14mm and 9/16 UNF helicoils together with a sizing tap of 5/8x20 t.p.i. I have heard from another member that Laurie maintained Admiralty thread was originally used. However, all helical inserts have a 60 degree profile. I need a cup of tea, a Bex and a good lie down. (note to foreigners, Bex was the brand name for an addictive Australian analgesic similar to "mother's little helper" popularized by the wonderful Mr. Jagger. I think you are a brave man, Phelpsy!
We have all done it Ken, Why so many different threads ?, I have just bought a Special tool, All The nuts and bolts are loose, And God knows what size spanner fits them !!, They are not A.F. or Metric, I would not have thought BSF, But dafter things have been done !. Cheers Bill.
I'll add a few more worms to the can. 
I've spent over an hour in the cold loft and have finally found my "Machinery's Handbook" - 1919 version. There isn't much said about the CEI thread except for the following summary:
60 degree rounded top and bottom.
Depth of thread = Pitch x 0.5327 = 0.05 x 0.5327 = 0.0266" (for a 9/16 x 20tpi).
Radius of the thread at top and bottom = 1/6th of the pitch = 0.05 /6 = 0.0083 (for a 9/16 x 20tpi).
Then I surfed around and found this site: http://www.stevenott.com/ceithreads.htm
Unfortunately, the first diagram doesn't conform to the Machinery's Handbook 1919. So I would discount it.
However, the two charts are interesting. Firstly it confirms depth of thread as 0.0266 (as per Machinery's Handbook 1919). Secondly, depending on whether you have a "CEI Thread" or a "Bicycle CEI Thread" the Core Diameters are quite different at 0.498 and 0.5093 respectively (for a 9/16 x 20tpi).
How many more worms can we get in to the can?
Peter B
Bristol, UK.
I've spent over an hour in the cold loft and have finally found my "Machinery's Handbook" - 1919 version. There isn't much said about the CEI thread except for the following summary:
60 degree rounded top and bottom.
Depth of thread = Pitch x 0.5327 = 0.05 x 0.5327 = 0.0266" (for a 9/16 x 20tpi).
Radius of the thread at top and bottom = 1/6th of the pitch = 0.05 /6 = 0.0083 (for a 9/16 x 20tpi).
Then I surfed around and found this site: http://www.stevenott.com/ceithreads.htm
Unfortunately, the first diagram doesn't conform to the Machinery's Handbook 1919. So I would discount it.
However, the two charts are interesting. Firstly it confirms depth of thread as 0.0266 (as per Machinery's Handbook 1919). Secondly, depending on whether you have a "CEI Thread" or a "Bicycle CEI Thread" the Core Diameters are quite different at 0.498 and 0.5093 respectively (for a 9/16 x 20tpi).
How many more worms can we get in to the can?
Peter B
Bristol, UK.
Which is in itself part of the problem for members who want the correct studs for their Molnar, Wyatt, DRAT, and other crankcases; we can find out what thread forms those manufacturers used, but we don't know if the VOC Spares Co ones will fit properly.
Peter B
Bristol, UK.
And while you are at it, why some main bearing holes are too small and oil pump sleeve bores are banana shaped
I'll add a few more worms to the can.
I've spent over an hour in the cold loft and have finally found my "Machinery's Handbook" - 1919 version. There isn't much said about the CEI thread except for the following summary:
60 degree rounded top and bottom.
Depth of thread = Pitch x 0.5327 = 0.05 x 0.5327 = 0.0266" (for a 9/16 x 20tpi).
Radius of the thread at top and bottom = 1/6th of the pitch = 0.05 /6 = 0.0083 (for a 9/16 x 20tpi).
Then I surfed around and found this site: http://www.stevenott.com/ceithreads.htm
Unfortunately, the first diagram doesn't conform to the Machinery's Handbook 1919. So I would discount it.
However, the two charts are interesting. Firstly it confirms depth of thread as 0.0266 (as per Machinery's Handbook 1919). Secondly, depending on whether you have a "CEI Thread" or a "Bicycle CEI Thread" the Core Diameters are quite different at 0.498 and 0.5093 respectively (for a 9/16 x 20tpi).
How many more worms can we get in to the can?
Peter B
Bristol, UK.
Funny you should mention Machinery's handbook 1919, I thought I had down loaded a 1916 copy of the page regarding the thread form. Be damned if I can find it on now. It had an excellent description of the thread form.
Steven
And which particular cooks broth are you complaining about?