These days there are readily available clutch adaptors to mate the Triumph Clutch to the A10 sliding plate oilseal scroll arrangement. An early Triumph 4 Spring clutch adaptor is flat on the backside, so nothing to keep the oil in when used on an A10. If this is the case, and an early Triumph adaptor has been used, the spacer could be a crude attempt to keep the oil in the primary chaincase. If this was a conversion done when the proper parts cost was prohibitive, this is a possible cheapskate solution. I would expect the clutch adaptor used here to not have a scroll. Otherwise if the clutch adaptor has a scroll the spacer is not needed, and is not an official part anyway.
The alignment of the engine unit and primary case with the frame is sometimes not quite perfect. Sometimes folks forget the circular spacer and gaskets between the crankcase and primary inner. If all is in order here, fit the primary cover and add a suitable spacing washer between the inner chaincase and the frame. There needs to no strain in the soft alloy castings. Like Morris says, loosening all the fixings can give the best compromise position before a final tighten.
Swarfy.
