Hi please can someone help me out. I have an early A12 motor (dizzy at the front of the block) I fitted a later A12 fuel pump to it and it won't work. I then put what I thought was the original pump back on it but it knocks and actually moves against the block !!!!!!!!!! I have had the engine for awhile sitting in my shed and it was working finne when i took it out of the car first can I fit a later pump to it and secondly why is the original pump moving against the block and has a distinct knocking comming from it I must have fitted it wrong some how. I am sure reading somewhere that pumps have a different lenght in the actuating arm. Would an A10 pump bolt up OK ?? I am buggered here.