Is this the answer, or is there really a problem?

[JohnD]

Over t'Pond, on the Triumph Experience message board, this tool is being eulogised as the solution to the problem, that 'decking' a block will lose the recess around the bore.

https://iskycams.com/shop/index.php?main_page=product_info&products_id=1565

It's a hand tool that sits on the top of the bore, and cuts a groove around it for metal o-rings, AKA 'fire rings', as seen above.    A V-shaped groove, not a flat recess, although no doubt a suitable cutter could be ground to cut a flat-bottomed recess.

But is this really necessary?   I would have thought that any machine shop that has the macinery and skill to do a rebore could set that engine to cut a recess,  if the tool that projects from the rotating beam is set further out, and the beam lowered into the bore for the necessary depth.      Is this not possible?

John

PS the tool costs nearly $400, which might be about the cost of this having part of the work done, as part of a rebore/decking etc.etc project.

[Nick Jones]

Interesting. Not something I’ve seen before. 
 

Suspect a pro engine builder would sneer at it and the very idea of simply wire-ringing a bore (presumably at least two turns to avoid a gap.

To do the job properly requires Wills rings, which are full circle and gas-filled. IIRC they are supposed to have matching semi-circular profile grooves.

Maybe you could use it to deepen fire-rings, but most times the block only needs a light touch and no need to recut the grooves.

[JohnD]

"Wills" rings?    NHOT! But Google is my friend and Trelleborg seem to be the goto place for them: https://www.trelleborg.com/en/seals/products-and-solutions/static-seals/wills-rings-o

There's a Wiki page too: https://en.wikipedia.org/wiki/Wills_Ring

Thank you, Nick, a discussion in the Common Room of Sideways U always comes up with valuable information!      Have you used these in your engines, or do you know about them in your business?

John

[Nick Jones]

Nope, but I know a guy who builds big bucks racing Imp engines and he sometimes uses them on the very high compression ones. Though it might have been Dennis P who first told me about them…..

I’ve not had much trouble with standard gaskets provided the head bolts hold torque. But then not built anything that powerful…..