Those BMC pumps again
QI have a fuel leak from the throttle spindle on my BMC 1.8 engine. I have removed the linkage but there is a quadrant plate that goes against the throttle stop that looks like it should lift off but it won’t move? Do you know how this comes off? I presume there is a seal or O-ring underneath.
PHILCOLES, via the CB website
ATONY REPLIES: All the BMC1.8s I have seen use a CAV DPA injector pump but they do not have a quadrant plate. Beneath the lever there is a disc with small holes punched around the edge. Dimples in the back of the throttle lever fit into whichever pair of these holes is in position for that particular use. This disc also has an extension that bears against either the idle screw or maximum fuel stop. The lever has a round hole in it and the disc an oval hole with two flats that match the spindle. I don’t understand why you cannot simply pull the lever and disc off once you have removed the nut from the spindle.
It is vital on these pumps that the throttle cable is adjusted so the disc hardly bears upon the idle stop when the control is set to idle. If there is any tension/compression in the cable it forces the spindle hard against the O-ring so leaks are likely.
The O-ring is on the spindle, not in the housing, so you could just pull the whole spindle and lever assembly out of the pump. To do this, locate the governor assembly locating screw and remove it. Then the spindle with lever should just pull out of the pump. You must ensure it is properly located in the governor valve when you reassemble.
I would advise that you Google for a hydraulically governed CAV DPA manual before going any further.