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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).
Analysis of issues and recommended modifications for the 4¼-litre Bentley, including costs.

Identifier  ExFiles\Box 115\3\  scan0007
Date  7th July 1937
  
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(5) Engine is dismantled for other causes.
If for any reason whatever a crankshaft is removed from an engine, it should have the additional holes drilled in both the pins and journals.

4¼-litre Bentley.

This chassis is in rather a different category from the 3½-litre in that, provided the main bearings do not hammer out, it may be expected to run for as much as 50,000 miles without bearing trouble. Nevertheless, the attached record shows that in six cases big ends have failed, and we know that cases like this will occur due to momentary shortage of oil. However, these cases are not sufficiently numerous at present to justify modifications to all the six hundred 4¼-litres in the hands of customers without large oil pumps.

The cost of the possible modifications to 4¼-litre Bentleys are as follows:-

(1) Large Oil Pumps.
The last 100 Bentleys made have had the large oil pump. About 600 have not. The cost of the large oil pump is £3.

(2) R.20.
£13/10/- as on 3½-litre.

X (3) Taking up Main Bearings.
£13/10/- plus cost of fitting time, say not more than £17/-/-.

(4) Drilling Crankshaft & Fitting Large Oil Pump.
Not more than £30 or an R.20 plus £16/10/-.

(5) Drill crank, fit large oil pump, fit new set of A.C.2. main bearings, £45 or a R.20 plus £31/10/-.

Our recommendations for dealing with 4¼-litres are as follows:-

A.{Mr Adams} Known Hard Drivers.
Fit larger oil pump
Cost to Company £3.

B. After 30,000 Miles.
Drill the crankshaft pins and Journals with extra lubrication holes whenever the customer can be induced to pay for it while the car is having an R.20.
Cost to Company - Nil.
  
  


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