I own ' 71 240Z with the needle and seat ( no Grose jets ) in the float bowl, and I'm trying to determine if the level of gas in the float bowl is adequate. I took the float bowl lid off and grabbed my calipers and measured down from the top of the float bowl 38 mm before I hit any gas, is this to low ? Maybe a better question would be, when the floats are set correctly, where does the level of gas in the nozzle suppose to be ? I read the article by Roger Garnett from ZHome.com and he says the level of gas should sit right below the nozzle. Is he correct ? I pulled my suction piston and looked down the nozzle and it's empty. The car starts and idles well, but power is down and it starts to stumble at 3500 rpm and won't rev past 4000. ( fuel starvation ?) It's starting to get cold here in Nebraska so I have to get this problem solved. One last thing, what's the timing get set at ? Thanks SKB

You can't measure the float level by measuring the fuel in the bowl with the cover off, because the float itself displaces fuel. Done that way, it should look very low.

Fact is, adjusting the float level is the most critical basic adjustment for the SU carbs. It is also a bit fussy to do just right. And it is also something that should NOT have to be done repeatedly, as once set it shouldn't change on its own.

Here is a good thread with lots of good advice on getting this done properly, especially a great tip from the SU gurus at ZTherapy (Bruce Palmer). I'd sit down and read the whole thing from start to finish.

http://classiczcars.com/forums/showthread.php?t=19362

Arne hit the nail on the head. You must measure the float level at the float itself. Do you have a Service Manual? This would tell you how to properly adjust the float. I made myself a "guage" out of thick craft paper to properly adjust the floats.