MTFCA Forum

Just curious what the advantages/disadvantages to the two types of OF carbs, one with fuel inlet at the top and one with it at the bottom? I know the top fill was the older style.

I've wondered the same thing. Used both examples on same car. Never any difference in performance. Hopefully one of the guru's will chime in.
Must have been for a reason.

Might the lower input make it easier to maintain progress when the tank was low and the incline rising?

Allan from down under.

Don't know of any OF's with inlet on the top. Would this be the later model RF aluminum carb?
http://www.mtfca.com/discus/messages/33 ... 1382274012

Stan Howe indicated to me that the low intake on the fuel bowl was a later development. There appear to be far more of this type than the others.

Allan from down under.

The upper inlet version dumps into a well which contains what is in essence a labyrinth assembly whereby sediment settles out and clean(er) fuel at the top of the well is allowed to flow in to the bowl. Fuel flow is very slightly but not terribly restricted with this arrangement. Unscrewing the cap on this well allows the operator to withdraw the entire assembly and dump whatever crud has settled inside. This screw is often beaten up pretty badly in in these carbs. Without a special-purpose tool to unscrew it, the top will become damaged and sometimes badly damaged very quickly.

The lower inlet version accommodates a more typical screen strainer, the design of which is shared across the Stromberg platform of the era. Far better fuel flow is accomplished, and there is true filtering rather than letting gravity separate out debris. I suspect this is a natural evolution where the fuel being purchased was far less likely to be polluted with foreign debris as was often the case in earlier years.

Strainer/labrynth with old and new screw tops:
Typical screen in lower-feed version: