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).
Technical report on carburetor and induction pipe depression tests.
| Identifier | ExFiles\Box 13\3\ 03-page078 | |
| Date | 28th January 1929 guessed | |
| contd : -2- induction pipe is 2.1" Hg. We aim at getting a depression of not more than 2" Hg. at 2500 r.p.m. which is the figure given by the RRCH. carb. for a choke area of 1.532 sq.ins. or 10.4% less area. We then completely removed the restrictor, the area past the choke being the same as past the restrictor, i.e., 1.710 sq.ins. The depression then fell to 1.7" Hg. This test indicates that the induction pipe depression is not entirely governed by the area past the choke allowed by the restrictor but that the restrictor exerts a throttling influence in the air intake, or entry to the choke. The choke was then increased in dia. from 1.475" to 1.575 and a larger restrictor constructed which would shut off the choke in the no-lift position. The test was repeated with the restrictor held fully open - it being arranged that the restrictor would lift .100 more than standard, and the area past the restrictor now came to 1.95 sq.ins. or the same as past the enlarged free choke representing 14% increase in area over the previous choke. The induction pipe depression was now actually higher than with the smaller choke and smaller restrictor being 2.4" Hg. This appears to be further evidence of the restrictor offering increased resistance in air intake. Looking at the carb. the restrictor appears to well fill the space between the two float chambers. We propose to test this by making a dummy restrictor so that when in its full lift position all that portion below the narrowest section for air flow which it forms with the choke is cut away. contd :- | ||