Holley NH passageway question

M

Marshall V. Daut

Well-known member
It's been a couple years since I drilled out Holley NH passageways. Today I began rebuilding a friend's NH and came across a minor problem while drilling the plugs to clean the passageways. In the attached photo that I shamelessly lifted from someone's past posting, the straw that is going into the long neck - inside of which is the jet - seemingly only goes through the hole into the open area inside. What does this hole do and why should it drilled out and then plugged? I can't see that it has any internal passageway for air or fuel to travel through. What is the purpose of this hole? Do I plug it flush with the internal threads for the threaded bowl drain plug?
I drilled out the brass plug and threaded the hole for a 10-24 plug, but am wondering what good this will do. A second NH that I disassembled has the open hole with NO plug. Now I'm confused.
Marshall
 

Attachments

  • Holley NH carb passages_resized.jpg
    Holley NH carb passages_resized.jpg
    45.6 KB · Views: 19
Unless it is plugged, there is a port just past the mounting end opening. The straight down hole from that end connects it to the angled passage, part of the idle circuit. There would no way to connect the tow passages without the passage that exits the rear at the flange. Maybe someone left the plug out in the past thinking the gasket would cover the hole anyway.
 
Thanks, redmodelt. The answer I needed was supplied on the MTFCA website a little while ago. 'Cleared up my confusion! Thanks to all for your help.
Marshall
 
You must log in or register to reply here.
Back
Top