64 Slant carburetor problems

When it idles rough, try spraying short shots of starter fluid down the carb throat. If it smooths out, it is running lean, most commonly from a vacuum leak. If no change, it probably isn't fuel related (check spark). I once got a Jetta idling great on just starter fluid at a picnic (found fuel pump failed). The girl didn't understand why she couldn't drive home like that (me under the hood spraying?). If too rich, it will usually idle smooth but pour black smoke from the exhaust.