Carburetor Central

I finally got the round top su's on this evening. I've plugged all the hoses to the extra stuff on the balance tube, for now. The pieces are intact. The egr is still present and hooked up. But since I removed its vacuum source, I don't think it will be opened. I turned the key and it started running. It is popping gas out the carburetors a bit. But, I think this is expected for being completely unbalanced? So, I am feeling good and the rpm's start to rise to 4,000 with choke and 3,000 without. So, I attempted to adjust the ilde screw. It didn't seem to have an effect -- all the way in or all the way out. Looking a little closer, I realized that the tab that shoul…

I'm cleaning up two round top carbs that came on a 2.8 engine in a 260 project car. Obviously they are not original to either. One carb has a damaged top, I took an original top and piston from a early 71 carb. Upon comparing the jet needle length I found the early 71 jet was about an eighth of an inch longer than the one that came off the car. Both needles are installed to the proper height. Were there different lenghth needles from the factory or am I dealing with a replacement? If it is a replacement what advantage do the short needles provide? Mark in Portland

Lots of SU round top parts from 3 screw and 4 screw hitatchi used on the 240z. $125 shipped anywhere in the USA. Everything has been degreased. Includes 2 bodies, 1 dome, 1 piston, 1 float bowl/cover, 2 nozzles, 2 butterflies, 2 throttle shafts, and everything else pictured. All are in used condition sold as pictured. Sent from my iPhone using Classic Zcar Club mobile

I have several questions regarding the precise fuel pressure both of the 3 screws round SU CARBS on my 240z will tolerate as i am pushing the fuel through an AIRTEX 8012S which is rated 5 to 9 PSI: 1. Should i measure the fuel pressure plugging a "T" before the front carburetor? 2. Should the pressure read no more tan 4.3 psi? 3. What if the pressure reads more than this limit but does not show any spill out of the fuel bowls? Will i need to open both fuel bowls and reset the level. THis was done by Ztherapy in 2014 and i would not like to mess with it.

Not sure if this falls under the “better mouse trap” or “new can of worms” heading but it seems worth knowing about ... https://roundtopsfuelsystems.com/

i pulled the carbs off my '73 (allegedly '72 roundtops) and also the carbs off the g/f '71. now i have questions. during disassembly i noticed a couple differences. the ones from the '73 had a four bolt flange for the damper and also had a black plastic jet assembly. the '71 had a three bolt flange for the damper and had a stamped steel jet assembly with some type of locking screw mechanism. otherwise, they appear to be identical. so the questions are, what's the difference? is one better than the other? are the internals interchangable? one other question, how much meat can be removed from the manifold and heads for a little better flow?

I worked a lot on the car today. Installed the fuel rail. The carbon canister hasn’t been reinstalled yet, but I’ve heard different opinions on it. what’s the opinion of how these fuel hoses are set up? I’m no mechanic, but want to make sure I didn’t screw this up. thanks in advance!

Any risk of testing the car without the fuel filter fastened to 3 screws Su carburetors (round top) ? How long can you test it without the air box filter on? Trying to get the correct mixture!!

it was running amazing yesterday then i adjusted the points to 0.18mm and started it up set the timing and purrfect then i am standing there after drining it home and it dies like i shut the key off now i have spark and fuel but no start?

After running too rich for months put new points and swapped the SM's for modded N-27's. I balanced the mix and set it lean, then set it 1/16 of a turn richer every few days. Now it goes lean when first leaving a stop sign, burbling a little except on very hot days, but runs well otherwise. I could easily richen it up but I love the gas mileage around town. I can drive for an hour and the gauge doesn't move. I've read that these engines like a rich mix but I seem to have more power when it's a little lean, especially on hot days. The N-27's are polished down at the mid-range, cruising, and top end stations so there's no lean miss or burbling when I get on it. No overheati…

Been searching the forum for ideas on my current problem. Final stages of complete restorations of my 73 Z. My latest issue is it running rich. I have replaced the 73 carbs with 72 round tops that I completely rebuilt. The car runs fines at all rpms and speeds (actual driving it). It smells rich and does some popping thru the exhaust. I should also mention I have headers on the car. The carbs have new .100 nozzles from z therapy and N54 needles. In an attempt to lean it out I've tried incrementally adjusting the Idle nuts 1/2 turn clockwise (did it 2 times 1/4 turn at a time). According to the 72 FSM says turning the idle adjustment nut clockwise reduces fuel and …

My '72 with stock L24 and SU's chronically runs rich. I know that there are many factors that can contribute to this. But, can the plug gap be set to eliminate some of this rich running? High end of the range?