Rolls-Royce Silver Shadow II - Engine Modifications to Meet Japanese Fuel Regulations

Service
Bulletin
Bulletin number E29
Circulation list I
Category c
11
Date
4 2 76
II I
II I II
TO ALL DISTRIBUTORS AND RETAILERS ~N JAPAN ONLY
II
ENGINE MODIFICATIONS TO MEEr JAPANESE FUEL REGULATIONS
APPLICABLE TO:
All Silver Shadow, T Series and Corniche cars.
DESCRIPTION:
Page
II I
OWing to the reduced amounts of lead specified in the 1975/76
Japanese Fuel Regulations and the complete removal of lead
from the fuel during 1977, it will be necessary to make
certain modifications to engines built prior to 1975.
A list of the modifications together with the original
specification appears at the end of this bulletin.
Basically for the 1975/76 P~gulations it will mean the retard-
ing of the ignition timing on all cars built prior to 1975.
During 1977 with the complete rewoval of lead from fuels it
will be necessary,on 1972 and earlier cars,to not only modify
the ignition timing, but also reduce the compression ratio by
changing from 9:1 to 8:1 compression ration pistons.
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MOTORS I
Car Division
1 of?.
11 I
Although reducing the compression ratio tends to result in the
engine running weaker, it should not be necessary to change the
carburetter needles. However, should driving problems arise
due to weak running, the slightly richer needles UE 40043 (Code BDD)
can be used or the next richer stage again ~"E 37088 {Code BAM).
This applies to the 6.75 litre engines except for Corniche
which already uses the UE 37088 (Code BAM) needles.
For the 6.25 litre engines no problem should exist with
regards to weak running as the UE 36062 {Code BAE) needles
are suitable for both 9:1 and 8:1 compression ratios.