Great info Bill! I'll certainly store this in the memory banks. Thanks for your help!
-Sean
ORIGINAL: William Robison
BUflash:
Well, here's the "Plastic Lover" chiming in. I have many engines with Perry carbs, including HB and K&B among others I've switched to Perry carbs. Not one has been trouble, Not even the "Pumper" K&B engines. Never had any other brand delivered with the integrated pump, so I can't comment on how well or poorly OS did the job.
The needle setting. Perry had two different design needles, the first had an open spring (First picture) that tended to have an air leak at low speeds, and would leak fuel at high speed. remove the spring and cut a length of fuel hose to replace it, but be sure the end of the hose stays on the little circlip. If it laps over and hits the mixture disc it wont hold your setting. The later carb had an o-ring inside the cup of the needle. If the later type wont hold a setting you need to replace the o-ring in the cap. Second and third pictures.
Always start with the mixture disc set at the center position, (last picture) rolling the slit forward richens the mix up to about 1/2 throttle, rolling it to the back leans the mix.
When you have the idle and high speeds running fine go to 1/2 throttle, let the engine stabilize, and pinch the hose between the pump and carb. If all is right the engine will pick up a slight amount of speed, and then fall off. If it drops immediately the fuel pressure is too low. turn the pressure screw in about 1/4 turn. If it picks up a lot you can lower the pressure if you wish, the engine will run fairly well at a rich setting. For best engine operation lean it a bit if it's rich. The 1/16 at a time on the pressure screw doesn't make much difference, it will take you forever. After changing the pressure you'll have to reset the low and high speed adjustments.
That "Extra" idle screw is a flow regulator, as has been said. It is adjusted only if the engine goes rich in inverted flight. I have never had to mess with one, and in fact Perry eliminated the adjustment from the later "Pump" carbs. Just leave it alone.
I really think most people have trouble with the Perrys because they are just too impatient to learn the adjustment. When they are right there's no carb that works any better.
Bill.