Hello, attached is a sketch with the dimensions for the MF270B (UK) dashpot wedge. It is essential to hold it securely in place when carrying out the 'Relief Valve Blow-off and Drop Rate' adjustment. This is the only way that you will achieve a consisyent drop rate. If you make a wedge it is essential that it fits inside the pump lever and allows the pump lever to move fully.
Also attached is the sequence for marking the lines on the drop arm.
DavidP, South Wales