Answer
Mar 03, 2026 - 10:56 AM
Based on our research, we found that the answer is no.
The extra/open hole(s) on the Holley 19-350 aren’t designed or plumbed to function as a regulator drain line. They’re simply unused ¼″ NPT ports that Holley includes for flexibility in plumbing or for plugging off unused connections — not as a regulator drain.
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