What are the 2 nipples for? One is for fuel obviously, but what about the
>other? Walbro's site is no help and I can't find any info on the net.
For starters, please don't post binary files here since it is by definition a text only news group. Better to post the binary in the binaries group and post a note here. That's "rec.binaries.radio-control".
The Walbro site isn't very intuitive, that much is certain.
At the Walbro home page, click on "Service & Aftermarket", then click on "Aftermarket Parts & Service", then click on the button in the upper right corner "Click to browse by Walbro number".
Then in the list "Select the Series for your part :", click on WT-433-1.
That's your carb, BTW. Says so right there in the photo.
I would hazard a guess that the second nipple is the atmospheric vent for the backside of the diaphragm, but having the parts breakdown and list should make it a lot easier to figure out. Cheers, Fred McClellan the dash plumber at mindspring dot com