I'm having my 1971 240z's engine rebuilt and I noticed that the person working on the car replaced my 4-screw carbs with 3-screw ones. Are the 3-screw carbs better? Should I tell him to put the 4-screw carbs back on?

Bruce Palmer is the guy to ask (Z Therapy). The 4 screw carbs are more period correct for a 1971 240Z, but I don't think that there is a functional difference.

I've had the 3 and the 4, the only advantage I found was my three had the dowels witch usually are broken off they seem to help line up the dashpots better, but I could be missing them on my 4 screw carbs. IF your going for accurate restoration change them back, but if it is a car to drive around or race it don't matter.

I prefer the 4 screw carbs. To me they are easier to line up the needle and nozzle without rubbing.

If you look at the needle and nozzle, you will see the 4 screw is a bit more adjustable in getting them to line up.

Which manifold is on the car?