Mystery Tappet.

[Colin Reed]

Hi Robert,
                   Judging from those sizes when fitted would have about 5/16" gap between cap & valve stem
                   even with a high lift cam would still leave 1/4"
                   My thinking is did they use longer stemed Valves in the Ulster Engines
                   The removable cap does allow for catering for different length valves ether by making a longer cap or
                    grinding the cap down

Hope that as not confused things more
Colin