Marvel Carb Adjustments?

[Doug in NJ]

Last year I picked up a virtually unused Marvel carburetor, and today I got around to inspecting it, cleaning it up, and installing it. It works pretty well- it gives plenty of power and does not have any tendency to make the engine die when decelerating. But there is one funny thing: I have to leave the GAV about 2 turns open. This seems to be the best setting for idle, normal driving, and full-power driving.

Is this normal for these carbs? Before I messed with the carb, I noticed that the shoulder of the GAV needle was bottoming out on its housing. Also, the housing was only partially screwed into the carb body. So I screwed the housing fully into the body, and then the needle tip was seating in the valve before running out of threads.

So I am wondering: is the housing is supposed to be only partially screwed into the body, and is the needle supposed to bottom out? Perhaps in the factory the housing was screwed into the body with the needle bottomed out on it until the mixture was correct, and then sealed in that position?

I'd love to hear what the Marvel aficionados have to say...

Doug