Originally Posted by jdaviscgaz
Certain of the metering rods and jets to be lined up. Noticing that the power piston has to be pushed at WOT before the gas is purged up to the exit site just above the venturi. Thinking that since the cylinder that the power piston is in is a tapered cylinder that I have the wrong plunger seat, and it is not sealing to push until the bottom of the cylinder. On the other models I've tried slightest movement of throttle actuated this part of the carb easily. The one I took out matched the one I put in but then again it didn't work either. Or fuel is just not getting to the power piston site which would have to be float level problems
Actually the part you're talking about is the accelerator pump. The power piston is controlled by vacuum and its job is to position the metering rods in the jets at the right level.
If the accelerator pump isn't working correctly, start by attaching the linkage to the hole nearest the pivot. That will give the biggest shot of fuel.
There are several different lengths of the rod the accelerator pump uses, if it's the wrong length this can have a bad effect.
If the springs are mixed up and the one for the filter is used on the accelerator pump, or the return spring is swapped w/the override spring on the shaft for instance, that can cause it to work poorly. If the piston seal is wrong it can have a hard time pushing fuel and/or allowing the pump to refill.
There's a ball that acts as a check valve under a screw in the float bowl, driver side. Be sure the ball is in place and sealing as it should. The check ball seat can be re-formed by carefully tapping an old check ball against the seat using a small punch and light mallet/hammer.
Sometimes the accelerator pump bore gets glazed where it doesn't seal against the piston very well. The bore can be lightly honed using 600 grit wet or dry and WD-40 or a similar solvent. I use a wooden dowel w/a piece of cloth wrapped around the dowel and the emery paper wrapped around the cloth. Then make like a boy scout starting a fire or like you're lapping a valve. You don't want to remove the finish, just break the glaze ever so lightly and to smooth the bore.