The SU cut-out

Sir,

With reference to Mr. C. R. Smith’s letter concerning the running-on in the Wolseley 4/50, 6/80 and the Morris Six, I hope I can offer some relevant information about the pull knob on the dashboard.

While at work at the Jaguar a colleague who had previously worked at Morris Engines brought up the subject of running-on in such vehicles as the Morris Six. I will try to give a brief description on the SU carburetter “anti-run-oh” device. The pull knob on the dash was connected via a Bowden cable to a Sliding tube which on one end had a sloped profile. On the end of the tube, that is on the slope, the slow-running adjustment screw resided. Therefore, when the knob was pulled, the slow-running adjustment screw followed the drop of the slope and therefore caused the throttle butterfly to close completely, and stop the mixture entering the engine. This device was at first used as a development feature but later was just put into production, and my colleague mentions that it was described in the hand book. He also assures me that this device was fitted hecaw.e of the post-war petrel and net because of the combustion shape!

Many thanks for a fine and very interesting magazine.

Great Kingshill.
John Paterson.