Carburetor Central

1,458 topics in this forum

1. 

   Fuel return line 1 2

   November 9, 2003 by tanny

   • 12 replies
   • 2.4k views

   On my 1973 Z there is a fuel return line. Since my car came with triple Webers, the return line was not hooked up. To help eliminate a vapor lock problem, I hooked the return line back up and put the fuel pressure regulator on the return line to create back pressure into the carbs. How did the stock fuel line set up create enough back pressure in the line to fill the carb bowls? There must have been some kind of restriction on the return line. Thanks, Victor.

   

   Last reply by 240ZX, November 14, 2003
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3. 

   SU's won't balance

   November 11, 2003 by alien-e

   • 6 replies
   • 2.3k views

   A little history: I bought my Z with a 4bbl Holley on it and decided I would do better with SU's, so I bought a pair on e-bay. They were gummed up pretty badly, but I put a lot of effort into them and got them cleaned up. Unfortunately, the needles were stuck in the jet tube (both). Halfway through the build, I got another pile of carburetor parts, that were the same models as the one that I currently have. So, I retrieved the needles from those SU's and finished the re-build. So, I installed the carburetors and they ran ok, but I think that the needles were bent, and the cylinders didn't "clunk", like they were supposed to. The choke on the front carburetor was sticking …

   

   Last reply by Chino 240Z, November 12, 2003
4. 

   are all round tops the same? 1 2

   November 4, 2003 by clutchdust

   • 14 replies
   • 2.3k views

   forgive me if this sounds like a rookie question, since i am, after all, a rookie. my experience with the Z consists of a little work i did on a friends '72 earlier this year. well, the good news is i'm picking up a nearly identical '73. apparently, the hitachis:cross-eye have been replaced with SU's. i am slightly confused though because although they look very much like the SU's on the '72, i noticed these have 4 bolts holding the 'dome' on where the other ones had 3. at least i think the other ones had 3. am i imagining things? were there two (or more) different types of SU's? anything i need to know about these carbs?

   

   Last reply by Bruce Palmer, November 6, 2003
5. 

   carb pistons and idle tuning

   November 5, 2003 by escapedan

   • 2 replies
   • 1.5k views

   I’m trying to understand what the pistons inside the carbs “doâ€�. The reason I ask is that after taking all the smog equipment off my 1973 L24 engine and capping all the left-over ports, my engine is idling at 2400+ RPM at 7degrees advanced. (even after warming up for 3+ minutes in already warm California) The only thing that seems to drop the RPM is when I manually lift the pistons inside the carbs leading me to believe they should automatically lift when the engine is idling. When the pistons are fully down, the high RPM’s return. Additionally, the car “diesel’sâ€� (continues to run, chugging and spitting raw fuel out of the rear carb) when I shut it off. …

   

   Last reply by 240ZX, November 5, 2003
6. 

   sticking throttle syndrome..

   November 4, 2003 by halz

   • 6 replies
   • 1.7k views

   OK...smooth acceleration off idle is something I am yet to achive. When I press the pedal there is no movement ...until I press a little harder... and then...vroom! Too much! I think the whole throttle assembly (from pedal to carbs) needs to be dismantled, cleaned, lubed and reassembled. I have disconnected a few of the nylon ball joint linkages in the engine bay and they are dry and dirty inside. What I plan to do is remove all of these, clean in petrol to remove old grease and then rinse in water to remove petrol. When all of the joints are clean and dry I will reassemble using graphite as a lubricant. Has anyone else ben through this procedure? Any tips?

   

   Last reply by halz, November 4, 2003
7. 

   Can you convert Webers to FI? 1 2

   October 30, 2003 by EricB

   • 17 replies
   • 4.7k views

   Someone was talking to me about this, that they were going to convert a set of triple webers into individual throttles and use fuel injection???????????? I didn't know what to say... Is this even possible? Can someone shed some light? Or is it easier to point me at a URL or book? Thanks, -e

   

   Last reply by EricB, November 2, 2003
8. 

   SU 4 screw stumble ... is there a cure?

   October 28, 2003 by Kerrigan

   • 1 reply
   • 1.4k views

   The carbs on my '71 are the original 4 screw dome tops. The car stumbles off the line unless I pull the choke most of the way out. Is there an easy cure for this problem? It does it tuned or not.

   

   Last reply by Dtsnlvrs, October 29, 2003
9. 

   Backfiring

   October 27, 2003 by Disposition

   • 10 replies
   • 2.2k views

   I am new here. I owned an '80 ZX model in High School and parted with it in college for some stupid reason. I finally found a 240 I was in love with and I am in the process of restoring it. I have been reading these forums all weekend and have found many solutions to problems that I have been having with my '72. The search engine has been very helpful. Since this is my first restoration project, and first experience with SU carbs I have a lot to learn. One thing I wasn't able to find in the search was where to sniff out backfiring problems. I'm honestly not sure where to start. I replaced one of the hoses on the carbs that was blocked, which helped, but I was wonderin…

   

   Last reply by Disposition, October 28, 2003
10. 

    Carbs Screws AAHHGG

    October 26, 2003 by seerex

    • 8 replies
    • 1.6k views

    I am trying to remove the 3 screws on the top of my round top su"s . On the back carb I have 2 of the 3 out and the 3rd is on its way to being stripped , I have sprayed the for two days with wd-40 and It seemed to have helped. Any suggestions on getting them out with out a drill, and does anyone know where to get replacement screws. The car had never been taken apart in its 31 year life so its a touch sticky with the nuts and bolts . Thanks Jeff:geek:

    

    Last reply by seerex, October 28, 2003
11. 

    Help! Need to Identify Needle sizes for SU Carbs

    October 2, 2003 by LedFoot

    • 3 replies
    • 2.8k views

    I'm just about to order my rebuild kits for my Carbs, they are the Hitachi HJG46W which are the SU ripoffs with the external float chambers. I've been told that there are three different needle/seat sizes for this particular model of carb depending on what vehicle they came off (240Z or 260Z). Now I've got these on an L28 and they were originally on the L26 that I replaced. But I have no idea if they were taken off a 240Z previously or whatever. Does anyone know how I can identify the needles etc required from any external markings on the Carbies? If I pull them apart now and check the needles myself then I don't have a car while I'm waiting for the rebuild kit and if the…

    

    Last reply by Murph, October 25, 2003
12. 

    need suggestions on tripple carbs. 1 2

    October 21, 2003 by Dreco

    • 22 replies
    • 3k views

    Hello, right now I'm running bored SU's (50mm) on a Rebello built 3.0L stroker motor. It's been suggested that I get the tripple carb set up, and I'm leaning towards getting it. Some say I should get Weber's because parts are more obtainable. But I thought I would get some input from the club before I make my purchase. my questions: 1. how much horsepower could I gain?? 2. Are there any cons running tripples rather than SU's?? 3. Which model of carb and intake should I get? (I'm willing to give up driveability for performance) 4. Where is a good place to purchase from? I'll need the whole set up, carbs, linkage, manifold.

    

    Last reply by LanceM, October 24, 2003
13. 

    Leaking SU carbs 1 2 3

    October 12, 2003 by seerex

    • 26 replies
    • 9.7k views

    My 72 240 had su carbs , on the top of the carbs there are two hoses coming out one is from the fuel rail and the other goes to the factory aircleaner . When I try and start the car fuel pours from the rear carb where the hose goes into the aircleaner ,I have tried to insert a pic . not sure if it worked. These are the only to fuel style lines from the top of the carbs . And only the one closest to the fire wall is doing this . As a bit of info the car hasn't been ran in about two years , I just replaced all of the ingition and starter < thanks to all who helped with that issue> and does have the smog pump hooked up <which I want to remove with all that crap >…

    

    Last reply by seerex, October 23, 2003