MTFCA Forum

Hello everyone, I was refurbishing a Holly NH when I came across something I haven't seen before (and can't seem to find references to here). It seems a few of the channels through the carb have been plugged intentionally; one of them on the flange and on of the inside the bowl. Pictures below. I don't recall my previous NH being like this and there are several posts about how you should be able to stick wires through these holes. Is there any reason why these channels would be sealed intentionally? Should they be drilled out or will this not affect much? The other holes appear to be clear.

The only way to drill passages is from the outside; just because the passages are drilled from the outside, it doesn't mean they are supposed to be open to the world...sealing the entry holes is how the passages become "passages".

Posts about running wires through the holes is merely to ensure that the passages are not restricted and can only be done after the plugs are removed. Read carefully on those posts and every single one mentions "drilling out plugs" and "resealing plugs".

Those drilled passages form the basis of the idle circuit. Low pressure draws fuel up into the venturi. If you left those plugs out it would be like trying to drink a Coke with a straw that had 2-3 holes punched into it above the liquid line.

Some advocate tapping and installing screws into the holes left by removed plugs. UGH. I'm not a big fan of that and it is easy enough (easier than tapping holes) to do it the way the factory did it and not deface the carb.

Everything you've shown is perfectly normal. Not to worry.

This explains why they are there and why they are plugged.
http://www.mtfca.com/discus/messages/59 ... 1472263600
https://www.mtfca.com/discus/messages/2 ... 1349760213

A few years back, Gary Tillstrom, a member of the Tennessee T's, posted a PDF of how he rebuilds an NH carb. Gary is a very knowledgeable model T man.
This will be my first attempt at posting a PDF file- I hope it works.

Got it! The wording of some of those other posts was confusing to me. All makes sense now. Thanks!

Usually the passages can be cleaned by soaking in carburetor cleaner overnight. Then the next day blow out with compressed air. You can also run a fine wire through as far as it will go. Use stainless steel wire so it won't break off in the passage. Put the nozzle right up to the passages inside the carburetor. This will force the obstructions out. If this doesn't work, then you can unplug them. After you work on them they can be plugged by a small lead plug.
Norm