SU carb dashpot chamber crack

[Doris53]

Hi all
I have been renovating a 1953 SII for the past year or so, and finally got to the stage of getting the engine fired up.
She ran up first time but subsequently died after about 5 mins or so. I checked the fuel pump, ran her up again and she did the same thing.
I had previously dismantled and cleaned the carb but decided something must be amiss, so today I stripped the carb down again. I was rather shocked to find the piston/dashpot housing cracked on the tube that houses the dashpot plunger. I have attached a couple of photos for clarity.
I am unsure how this crack has occurred. It may have been there previously but I did not notice when I first stripped/cleaned. The engine was not running pre-restoration so I have no benchmark from before.
So, I am wondering if any others have seen this kind of damage before and how it may have happened. Also is it likely that some of the oil, possibly seeping through the crack, into the piston chamber would cause the running (or not) problem I described?
Interested to here peoples thoughts.
TIA
Steve
P.S. I have contacted Bryan to source a replacement if available.

[svenedin]

Not sure really but possibly caused by a side impact to the dashpot when the piston was in the down position? Carburettor dropped on the floor when off the car?

[King Kenny]

Is it a crack or machining mark? They do not look as if the two are in the same place and the end of the chamber is unmarked. I would think that a blow heavy enough to crack the pot would also deform it in some way.

[alanworland]

Block the bore and blow down the other end to confirm it's cracked?

Alan

[Doris53]

Thanks you for the responses.
Prompted by the responses I have taken another close look at this. It is rather more like a deep gouge than a crack but I was concerned it may seep oil through. I guess it could be a machining mark; it's not aerospace quality we are dealing with here after all!
I blocked the end and blew through (just using my lung power!) and that does not suggest it is cracked, at least not enough to let that low pressure air through. So I have reassembled and refilled the dashpot with oil. If all is well in the morning I will mount it back on the engine and see how it goes.
Cheers

[Myrtles Man]

I blocked the end and blew through (just using my lung power!) and that does not suggest it is cracked...

Just a thought and I realise that now it's reassembled it's no longer of relevance in this instance but, instead of blowing through the tube, if you had sucked with all your might then held the end sealed with your tongue to form a partial vacuum you would soon have detected any leak because you would have felt your tongue released as the air leak re-filled the tube.