Holley NH Questions

[Plankhill]

Did all of the bowl side drain types have the long throttle and choke levers?
When did they change the orientation of the data plate from reading from the outside to reading it from the inside?
It appears the side drains were one way and the later ones the other.

[John kuehn]

Go to resources on this website and to the
older version of the encyclopedia.
Click on carburetors and you can find pics and information of the NH carburetors. Enlarge the pics to see differences and changes in the NH. You can use Lang’s catalog also to date what changes were made by the years the parts were used.
Hope this can help.

[Corey Walker]

The offset drain NH’s came with long arms. Some of the earlier center drains came with long arms. The casting for the side drain NH’s was different, having the air bleed/vent hole to the side requiring an extra passage to be drilled and plugged. The casting was modified when the center drain came out with a couple slots in the bottom to allow all the gas to drain out from the center but the long arms remained. Later this casting was simplified further, the air bleed hole being drilled straight down into the mixing chamber without the cross drilled hole and plug, eliminating a few steps in the manufacturing process. This change and the shorter arms came at about the same time with some overlap of the long arms. Some of the first swaybacks lacked the name tag and had the brass vent like the early straight through models and some of the straight through’s lacked this and used the familiar ID plate that said “Holley” but were backwards like Kingston ID tags. The early straight through used cast arms carried over from the G, the short arms were modified with offsets later on when the new swivel top mixture adjuster was introduced and also the brass staple for the throttle and choke plates was discontinued and the plates were held in place by upsets punched into the plares. These in 1926 also came with a slightly taller float to compensate for the increased fuel pressure from the cowl mounted tank. The vaporizers used this float as well.