The one the needle valve goes into. Basically, your problem appears to be that the float bowl empties, and it takes a large open throttle to refill it, and then start sucking fuel. That delay is making it idle like crap and hesitate. You need to figure out why the float bowl is not filling up and staying full.
Well I'm pissed, probably taking the day off work tomorrow to try and get it running.
In other news I'm going to do a small announcement in my thread, and later were going to do a big announcement with a group buy. Some of you may have noticed the links in mine and seans signatures, but SADFab is official. Website and everything.
The website is very basic right now, as its just a copy of my personal site, slightly edited. But its a place to show off our "products" which is really just us doing group buys for our open source projects.
Thats right, everything we do/design is going to be open source, and we will supply all dimensions, CAD drawings, schematics, wiring etc. Basically if you have the tools, you can reproduce everything we do.
Our goal isn't to make a profit, but to share information, and cheap products with the community. When we do group buys we will calculate in a labor cost, and a small administrative cost to cover websites, stickers, etc.
Our first product, and the one that really started this idea is delrin bushings. More information will come in the official announcement but expect an entire delrin bushing conversion at a price that beats everything else available.
Give it a bump of carb spray when it's idling like ****. If it comes alive, fuel issue not ignition. Sounds like lean spitting starving for fuel to me. Might be sucking the bowls dry/bad pump. Is it mechanical pump or electric? If it revs/runs under power it's probably not the pump. A weak mechanical pump might not work at low revs, seen that before on a 302 long time ago.
Also if you have a vacuum gauge, what's it show? A vacuum leak is most likely problem if it's not a pump and you've already rebuilt the carb.