17-05-2018, 08:51 PM
This topic was covered at length in the old website and the virtue of the various SUs was agreed. Besides, a polished horizontal (not semi dd) SU looks neat.
The piston and aperture of the 1 and 11/8 are the same; the former may give a more progressive throttle action . The horizontal 1 1/8 with dashpot ex postwar Morris is relatively common.
Where I lived involved a mile pull every evening up a road constructed for the early trams so had a uniform grade which matched the Seven flat out in 3rd. So every day was a road test. A carb bored to 19mm was a slight improvement but the 1 1/8 SU better still. Made as much difference as the later head so must represent a couple of hp or so. Also very smooth in stop go traffic. Curiously a larger manifold seemed to not assist. The needle size can be checked by manipulating the start enrichment.
I retained the Morris needle and did 38 mpg flat out everywhere. In earlier times as original driven at 40-45 a carefully checked 50 mpg was routinely attained on trips and presumably could with the right needle.
The piston and aperture of the 1 and 11/8 are the same; the former may give a more progressive throttle action . The horizontal 1 1/8 with dashpot ex postwar Morris is relatively common.
Where I lived involved a mile pull every evening up a road constructed for the early trams so had a uniform grade which matched the Seven flat out in 3rd. So every day was a road test. A carb bored to 19mm was a slight improvement but the 1 1/8 SU better still. Made as much difference as the later head so must represent a couple of hp or so. Also very smooth in stop go traffic. Curiously a larger manifold seemed to not assist. The needle size can be checked by manipulating the start enrichment.
I retained the Morris needle and did 38 mpg flat out everywhere. In earlier times as original driven at 40-45 a carefully checked 50 mpg was routinely attained on trips and presumably could with the right needle.