I see you have a 1960 engine.
I'm wondering if you have 1958 or earlier rockers, or at least the one that squirts.
Starting in 1959 Chev moved the groove inside each rocker 1/4" off center so it did not line up with the supply hole.
If 1950-58 rockers are used on a 1959-62 engine they can squirt, that is where the drilled head bolt comes in to stop this.



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