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General => Douglas Motorcycles - General Discussion => Topic started by: Ian on 23 Mar 2005 at 20:45

Title: Question on OHV inlet manifold
Post by: Ian on 23 Mar 2005 at 20:45
I need some advice on how to fit the inlet manifold together on my OHV 600. It has a pipe from each head with an alloy casting they slide into. The casting has grooves that look as though they would take an o-ring or similar. However I see no way of positively locating it ? There is a hole in the casting but it goes straight through the groove the o-ring would sit in. I really don't understand. Help !!
Title: Question on OHV inlet manifold
Post by: Doug on 24 Mar 2005 at 04:55
Ian,

From the 1925 OB&OW handbook:

“The induction pipe joint is of special patented design.  Where the induction pipe enters the manifold, an annular groove is formed on the inside of the casting, which accommodates a piece of oiled worsted, that is threaded through communicating holes in the manifold and induction pipe.  By turning the induction pipe to the right, the worsted is caused to fill the groove, thus providing a flexible, air-tight joint.”

(https://www.douglasmotorcycles.net/proxy.php?request=http%3A%2F%2Fwww.douglasmotorcycles.net%2Faa-files%2Fimages%2Fdoug%2F2005%2Fgb250702_1.jpg&hash=52fee7ad4a52580547497055f945a638)

The illustration below should make all clear.  This same method was used on induction pipes for the WW1 rotary engines (example: Bentley BR2), though there they used a ribbon-like material lead in through a slot.  The end of the ribbon was stuck to the tube with a daub of Seccotine, some sort of glue, so that it would be drawn in as the tube was turned rather than just slipping.  

(https://www.douglasmotorcycles.net/proxy.php?request=http%3A%2F%2Fwww.douglasmotorcycles.net%2Faa-files%2Fimages%2Fdoug%2F2005%2Fgb250702_4.jpg&hash=4649c289aac7700127de5cf372afa701)

-Doug
Title: Question on OHV inlet manifold
Post by: Ian on 25 Mar 2005 at 03:44
Thanks Doug - that makes sense !!