My newly acquired 1954 235 has the same issue. I was going to post the same question. Why was the tube pinched off??

You can see it in the pic all the way to the right on the rocker arm shaft.
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Chuck
1950 Chevy 1/2 ton (all original)
1951 Chevy 1/2 ton (future streetrod)
1941 Chevy coupe
1938 Chevy coupe streetrod