- Nov 20, 2004
According to the INOA Tech Digest, Superblends were introduced in at S/N 207197.
The INOA Tech Digest 207197 number is incorrect as 207197 was when the change in housing diameter occurred.
"Service Release No. N2/6 July 1972
Field experience with the 1972 models (incorporating two single lipped roller main bearings) indicates a small but significant premature roller main bearing failure rate. Reported failures have been confined solely to the one type of bearing.
Action:- When replacing defective roller main bearings, ensure the replacement is a Skefco double lipped outer, single lipped inner spool type NJ306, with a specified nominal internal diameter clearance of 0.0008" - 0.0012" (0.02mm - 0.03mm) prior to fitting . Ensure the crankshaft journals are carefully cleaned up, removing all signs of butts or scoring before fitting the inner spool. Models subsequent to Engine No. 207197 incorporate a nominal increase in bearing housing diameter to overcome any significant tendency to excessive closure of the single lipped outer series of roller bearing."
Note that "NJ306" is not the 'Superblend' as the original Superblend was the R&M 6/MRJA30. The later FAG 'Superblend' was the NJ306E.
"Service Release No. N2/9 August 1972
In order to extend main bearing life, a change of roller main bearing specification has now been authorized and fitted on production engines from Engine No. 211891. The new roller bearing is designated 'Superblend' with an increased load carrying capacity and is supplied under Part No. 063906 (manufacturers part number R&M 6/MRJA30).
Action:- Where engine units are stripped for examination, or the need for main bearing replacement, fit only roller main bearings Part No. 063906 in place of the previously specified 063114. The new bearings are fully interchangeable, and should be fitted in pairs for maximum reliability.
More Superblend info.: