Someone had asked me a question recently about what does the two screws and a little tiny brass rod do in a Perry Carb.
On some Perry carbs, not all of them, it appears to be just the PumpCarbs not the standard carbs there are what look like two screws inline and right behind the fuel inlet fitting. The top screw has a narrow tip to the end, whereas the other short screw is fitted into a brass insert screwed into the carb. In between the two screws is a little brass rod.


You can see it here in the carb body


Here are the two screws and the little tiny brass rod showing how they look when put into the carb.



Anyway, when I researched it I found that some Perry Carb instructions mentioned it in the exploded parts diagrams, but not in the parts list or in the instructions.
I finally located a set of Perry Instructions dated 1978 for my Perry Carb setup for a Rossi .60 engine. The screws and brass rod are called a "Slide Valve".
When everything else is adjusted on the engine and you bring it up to full throttle and then hold the plane inverted, if the engine runs a little rich, you can lean it out by turning the top screw (the one with the narrow tip) in 1/4 turn increments counterclockwise to lean the engine out more. The default setting is to adjust the top screw out 2.5 turns from when it stops when screwed in. The brass rod acts as a gravity operated valve when the engine is inverted and it obstructs the fuel flow going to the engine.

Anyway it is a pretty cool feature that I had never noticed before on the Perry carbs. I have a number of carbs and none of the instructions mention this feature in them or what to do with it, including other pump carbs too.



Here are some pics of the inner throttle body, spray bar and idle disc and how it looks outside of the Perry carb:
Front side of spray bar

Back side


Here is the instructions for my Perry PumpCarb for a Rossi .60 engine: