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Viton rings for Head to barrel dowels

Home Forums TR3OC Members Forum Viton rings for Head to barrel dowels

This topic contains 7 replies, has 4 voices, and was last updated by  Duncan Billingham1 3 weeks, 6 days ago.

  • Author
  • #7220

    Duncan Billingham1

    Has anyone used viton rings to seal around the dowels for the head to barrels mating?  If so, what inside/outside diameters and ring thickness were used please?   Would 6.35mm ID  / 9.91mm  OD / 1.78mm thickness be suitable?  Can anyone suggest a source of this?  Thank you.

  • #7221
    David Lord
    David Lord

    Whilst I’m sure this is a good way to prevent leaks in this area, I think it is over elaborate. Simply using a light counterbore and a smear of high temp silicone sealer creates a very good seal.

  • #7230

    Andrew Stroud

    for a source of O rings including in viton try simplybearings.co.uk

    Great web site to find and order many sealing and bearing products, I have always had excellent service from them.

    Regarding the size of O ring to use I would check a supplier’s web site for a down load of their design notes, I have one from James Walker which is very helpful to find the correct dimensions for an O ring installation. Contrary to popular belief rubber hardly compresses but deforms so it is important to get the correct clearances in any groove or housing to allow the O ring to move.

  • #7298

    j phillips


    I did this mod on a t150 that just would not stop bloody leaking around this area – I used a std copper gasket bored the appropriate holes out and fitted viton o rings – worked a treat. Sorry, can’t remember the size, but I wasn’t overly technical about it – snug over the dowel, and allowed the same expansion space horizontally as the oring was thicker than the gasket – again, not much 0.5,mm or so. Plenty of online suppliers that allow you to browse their site and pick what you need.


    • #7299

      j phillips

      Just found them ! 9.37 x 6.1 x 1.56 or thereabouts.

  • #7394

    Duncan Billingham1

    Thanks very much for the replies.  Sorry I’ve only just got back to dealing with this.

    I’ll try one more time before resorting to the viton rings option.

    David, what do you mean by “using a light counterbore” (what is being counterbored?) and where do you suggest to smear the high temp silicone sealer ?  (Just the upper surface around the dowel holes?)  Any recommendation as to which silicone sealer to use?


    Thank you,


  • #7395
    David Lord
    David Lord

    It is just evident on this old picture of mine:


    A smear of silicone around the top of the dowels creates the same effect as fitting an “o” ring.  I tried assembling the top end about three times in an attempt to cure a smoking engine and on the final try found this cured it.

  • #7404

    Duncan Billingham1

    Follow up – Head gasket refitted as recommended by David and now there are no head to barrels mating leaks.  So, thanks for the advice.  I haven’t tested it on a road run yet as I need to refit the choke slides (to a brand new set of Amals) to get it to pick up when cold – but that’s another thread, possibly.

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