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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).
Test procedures for Wraith III and Bentley II engine units, focusing on bore wear, piston, and ring comparisons.

Identifier  ExFiles\Box 155\2\  scan0253
Date  25th October 1938
  
-3-

Wraith III No.1 Unit.

Bore wear tests, 3 liners, in static cast std. R.R. block iron and 3 liners in static cast Chr.Md. alloy.

To serve two purposes, carry out tests under condition (c) of head cracking tests but maintain full load running at 3,000 for ¼ hr. before shutting down.

(a) Carry out 50 such cycles, remove head examine valve seats and measure the bores for wear.

(b) Repeat with Molybdenum cylinder head which HPS{Horace Percy Smith - Experimental Factory Mgr}/FN is now preparing.

No.2.

Bentley II No.4 Unit.

Complete piston comparisons and issue report.

Following the above with the original Aerolite pistons we should obtain a ring comparison as follows -

(a) Use existing rings and run 1 hr. runs at 4,000 r.p.m. until a consistent result is obtained.

(b) Fit a set of Wraith type scrapers and repeat (a)

(c) Fit a set of Multivent scrapers and repeat.

(d) Fit a set of Bentley type of high pressure scrapers.

(e) Cell faced scrapers from Wellworthy.

(f) Fit new normal 2nd. compression rings.

(g) Fit L section rings in 2nd. compression rings.

(2) The chrome molybdenum blocks should be progressed and one fitted to B.II No.4 together with 3 old standard EB.2844 pistons (Aerolite) and 3 similar pistons but having been heat treated at R.R.

Oil consumption to be checked to note that it is normal with this type of block.

CONT'D.{John DeLooze - Company Secretary}
  
  


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