Originally Posted by Snakeoil
They are not washers. They are tubular rings, like a napkin ring. I suspect this was the first attempt at restraining the expansion of the seals.
According to a post by John Healy
, the wedding band was not introduced until 1969 but many builders retro fitted them, quote:
"When the round section "O" rings where introduced in 1969:
a: The Buna-N (70-7310) "O" ring was specified for both top and bottom.
—After experiencing problems Triumph issued a service bulletin, mentioned by Paul above, introducing the wedding band and square section seal (70-3547).
—Triumph also introduced the Viton "O" ring (71-1283) to replace the Buna-N at the top. Viton will withstand more heat than Buna-N.
—Most engine builders have routinely started using the Viton "O" ring (71-1283) at the top and bottom.
b. The wedding band and square cross section seal was not installed.
—The wedding band was introduced into production for the 1970 model year.
—During rebuilds many mechanics adhered to the Triumph service bulletin and retro fitted the wedding band and seal.
—Although there is little published, THERE ARE two variants of the wedding band. If one takes the time to measure stock wedding bands one will find that there are two sizes.
c. In a 1965 service bulletin Triumph specified .030 to .040" for push rod tube crush. If there is too much crush you will bend the head and cause extrusion failure where the "O" ring deforms and is pushed out the gap between the head and push rod tube. Typical crush on a round section "O" ring, of the size found on the push rod tubes to affect a seal, is .010". The .030" to .040" assumes the use of at least one square section seal. In fact when this specification was given two were used. The square section seals will tolerate more crush than the harder round section "O" rings."