Frank, the cannon and redline are the same maniflds for webers, they look like they came from the same mold.
The fuel line into a fuel block with equel lenght to the carb will have each weber having the same pressure at the needle an seat.
I ran a Z back in the 70's at club level, webers etc, ran standard fuel pump no problems, fuel block set up, webers were off a Prince Skyline GTB,I had a Lynx manifold,very small ports so I went to the Warniford(cannon/redline) manifold, huge difference in breathing so much so I had to rejet.
Webers are fine but are controlled by physics, large chokes are no good if low revs are used, your engine can only suk a certain amount of air at anytime, if the choke for a certain size engine is say a 30mm then putting a 45mm wont work well, if at all.
The smaller the choke the better the car will drive but the larger chokes give more power, depending on other mods to the engine.
the air and fuel should be about "60" in number between the two, thats a good start point, 120 fuel/180air
The Idle screw should be no more that one full turn out, half to 3/4 is good, if the screw has to be more that one full turn the mixture isnt right
Hope that helps somewhat
I have posted a pic of my Z in full flight!!

Thanks ZardoZ! I'm planning to put the Webers on this winter. The 2.4L is rebuilt stock, with just a little shave off the head and a slightly bumpy cam (I don't even know the grind, and neither does the previous owner). The DCOE40s have 30mm venturi in them, which was slightly too little for the 260Z they came off of. But they might (might) be just about perfect for the nearly stock 240. I do want to brush up the manifold a bit ~ it looks rough inside and a very little effort might make it breathe easier.

Hey! I hear it's a bit warm down there in Australia just now? Our tiny state is buried in snow, and I haven't seen a Z car on the roads for weeks! (They put salt and sand on the roads to keep everyone from spinning out ~ it eats Z cars very quickly if you drive in it).

That's a nice looking 240 you're pushing there, mate! Looks like "all business" from this end. The only time we Yanks get to see the twin mirrors mounted on the fenders (sorry ~ wings) like that is on the Fairlady. Looks like you might have done some things to your suspension, the way it's tracking thru the corner all flat like that. Tell us more about the car?

Frank T

Thanks Frank, the car is 1971 240Z, was a metallic blue,I repainted to a dark blue, Volvo colour.
Twin mirrors were standard issue.
The suspension was simple, I cut one full turn off the springs, yep standard springs. I changed the oil in the struts to BP course plus, thats a heavy grade engine oil, fitted 260 2+2 front and rear roll bars, thats it.
Handled fantastic but very stiff, I was drifting on the track before it became "Drifting".
Back in 1973 there wasnt much around for Z's.
I also fitted an aluminium block in the steering, where the inner column meet the outer one, theres a rubber connecter, about 2 inchs thick, the alloy helps to take a "free play" in your steering.
I have some other pis, the first one is the first event I entered, standar suspension

This pic shows the suspension "in full song".
This was taken a Warrick Farm Racing Circuit, now closed.
This is Creek Corner, a sharp hairpin, speed is about 80mph using only half road lines, suspension is tight but the tail likes to play .

RIGHT! You've got it bent all out and ready to lift that inside wheel ~ exactly like my stock 1970 did. You also have the plexiglass covers over your headlamps ~ I wanted those in the worst way back in the 1970s, but they were 1) illegal in most US States, and 2) $40 a pair, which was astronomical in the 1970s.

When I bent my Z over hard enough I could rub the tires inside the wheel wells ~ not a big deal for cornering, but when the front wheels touched it actually effected the steering and got a bit hairy........

*(Sorry, this was intended for the first photo ~ you must have added the "flat suspension" photo while I was typing!)

This pic is JG860 at a motor sport park,Amaroo Park, also now closed Amaroo had a main tarmac circut, tarmac hill climb and the dirt circut, very popular with car clubs now replaced with suburbia
suspension working well,tires were the standard Bridgestone RD 102, this circut I tended to dominate
ZED's love the dirt!!

Yeah its HOT here, we are having a heat wave, I think ten days of 40c or above, 36c is 100f, it was 50c two days in a row at my place.
Frank,I think the 30mm are fine for a 240 with slight mods, theres a equation or such to work out choke sizes for different size engines, much more than this is a waste BUT you an increase chokes If you have
BIG valves, big exaust, good grind cam..etc.
Large chokes means alot of "bog" down low
JG 860 ended up with a 260C block,240 head, (260's were only new when I was running)larger jetting for the webers, 36mm chokes and this was a daily runner. 35/75 cam with a 2 1/2inch free flow exhaust, sweet sound to!!
someone I know fitted a twin cam turbo toyota engine to his Ferrari GT250 lookalike and complained the thing STILL sonded like a Z!
ya cant keep a good car down!!
Steve