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From the Rolls-Royce experimental archive: a quarter of a million communications from Rolls-Royce, 1906 to 1960's. Documents from the Sir Henry Royce Memorial Foundation (SHRMF).
Bore sizes for Austin 12/6 engines and the performance of Specialloid pistons in Leyland diesel engines.

Identifier  ExFiles\Box 131\4\  scan0267
Date  7th June 1937
  
K/W.
Rm.{William Robotham - Chief Engineer}

1113

K/GWH{George W. Hancock - Head Chateauroux}/DPB/7.6.37.

AUSTIN 12/6 ENGINES. There seems to be a certain amount of doubt regarding the correct bore size of this engine and, for the guidance of our readers, we pass on information given us by the Austin Company. The bores are finished to a working tolerance of .0015", varying from 2.410" to 2.4115". The Specialloid Pistons are finised suitable for a normal bore size of 2.4115" equivalent to 61.25 mm. Specialloid reference number is A.152 and the retail price is 14/-d.{John DeLooze - Company Secretary}

SPECIALLOID IN LEYLAND DIESEL ENGINES. Some remarkable figures have been supplied by East Midland Motor Services regarding the performance of Specialloid Pistons in their vehicles. The Pistons are left in service for 100,000 miles, when they are withdrawn and the ring-grooves machined out, oversize rings fitted, the Pistons complete being returned to service for another 100,000 miles. The average wear when the Pistons are removed is .007" in the ring grooves and .005" on the rings, whilst the maximum cylinder wear averages 12,000 miles per .001". The Specialloid reference number is L.120.

GWH.{George W. Hancock - Head Chateauroux}

I have taken these items out of the Specialloid Bulletin. N°6. possibly this may interest you.
Rm{William Robotham - Chief Engineer}/GWH.{George W. Hancock - Head Chateauroux}
  
  


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