Help with brake master cylinder

I have had my MC lined and rebuilt, but it has a fault. Fluid leaks from the push rod end. Trying to establish what is wrong. The company that did the work say the piston is not genuine Lockheaed and they feel it is too short. Anyone got any pictures?
These are the bits from mine, but I have no “before” Pictures as I did not do the job .



Is the bore good and smooth?

It has been relined in stainless. The problem seems to be the piston is going too far down the bore and the rear seal going past the intake hole.

Yeah, they could be right. The Lockheed piston number is 21421 in both the 120 and 140 masters, although the assembly number changes because there are different pushrods.

Would you have any dimensions of the piston?

I have a NOS Girling major rebuild kit I got off ebait some years back that was advertised as being for an E. It wasn’t, big surprise. I’ll try and find it and get the part number. It has the entire guts. Might get lucky and it’s for an XK.

It looks like the mystery is solved. Thanks to Roger for the photo, my piston is 51mm long . The leak would only happen if bleeding the brakes via the pedal. Under normal use the pressure in the cylinder would stop the piston traveling too far.

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I’m on my 3rd master cylinder and am still getting drips on the garage floor from the pushrod end. I wonder if it’s just residual fluid from when the brakes were being bled…? I’ll slip the boot off, give it all a good clean and see what happens. I did manage to buy a NOS master cyl still in its original wrapping, which I was thinking of having sleeved in stainless at some point.