Carburetor Central
If you have questions about the SU Carburetors, this is where you can find the answers.
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The parts catalog refers to this item as "Stopper - idle." Can anyone explain what this part does? Mine have gotten totally loose. Maybe it's sometimes referred to by another name? Two visuals attached. Thanks hugely in advance.
Last reply by SteveInOakland, -
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- 7 replies
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I just got my '72 240z running again, for about 5 seconds. I installed a Carter P60504 electric fuel pump with an advertised shut off of 4psi. From what I have read the SU's do not like anymore than 3.5psi. Upon turning the key and letting the system prime fuel started pouring out of the air cleaner/intake side of the carbs at the bottom of the large opening. I unplugged the fuel pump, waited a minute, turned the key, and the car would run until it emptied the fuel in the carbs. So my question is, if the floats and needles are working properly would the keep fuel from filling up the carbs and leaking out? If my floats and needles are fine then I am pushing too much …
Last reply by Hardway, -
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I just discovered that the nozzle on my front SU is loose. This is the fuel feed nozzle on the bottom, please see attached photo and illustration. It's loose, as in I can rotate it with my fingers, to the limits of the two attachments. Since the mixture adjustment nut is right there, I'm hesitant to try tightening things before I know what I'm doing. What can I do to get this thing tight? These are 4-screw SUs, btw. Thanks in advance for any and all help.
Last reply by SteveInOakland, -
- 4 replies
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I just ran it tonight with 29mm fuel level (measured from top of main well). Is 25mm down a typical level for an L24? (i.e. my fuel is 4mm too low)? Thanks
Last reply by 240260280z, -
- 9 replies
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Hi, After watching Just SU DVD so many, I decided to rebuild my '72 3 screws SU carb. It took me 3 hours to clean up 1st carb to remove 40 years gank, but 2nd one took me just 1 hours. Following DatsunZgarage instruction and use clear tube to adjust float level for both SU carb. http://datsunzgarage.com/engine/index.htm http://forums.ctzcc.com/viewtopic.php?t=4181&sid=b15c6070a9563fa4173bb07bbd52d213 It took me so many times to adjust float setting matching to 23mm line for both carb. Them, put back everything, spray Engine Start Spray, it start a bit and stole. Adjusting choke level, nothing is improving. No matter what I did, when I spray, it runs a bit a…
Last reply by tamo3, -
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The main jet, emulsion tube and Air corrector all must hold hands in order for the main circuit of the car to act as it should and when it should. Understanding the function of each part is critical to being able to tune the car. Blue has done so many great explanations of carbs, interiors, etc that I thought I would try to add to some of the core knowledge on the board. I am by no means an expert, but at times, I have been told I can explain things in a very easy to understand manner. So lets talk about the air corrector on Webers (or Mikuni's I guess as well). The air corrector allows air to come into contact with the fuel coming form the main jet and then enter t…
Last reply by 240260280z, -
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Cleaned the needle valve and tried the blow test. The pin on the valve hangs down about 1/8 inch or so. About half of that is free play. The valve closes just when the spring is felt. It tests OK when the lid is in the normal position but if I flip it over just the weight of the pin (no float attached) is enough so you can't air blow through. Is that correct or is the spring too weak? BTW noticed alignment of the hose bib of the banjo with one of the holes in the bolt causes more air (gas) flow. If the holes are off and the lap of the filter screen happens to cover the hose bib hole, it flows way less. Maybe because my screen is out of round, not new, just cleaned. …
Last reply by Stanley, -
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I am planning my build of an L28 3.07 stroker with most of the bells and whistles and I will have to decide soon on either SU's or Weber/Mikuni's. This will be a street driven car with some track/autocross. I have read a lot of the archived threads and basically it comes down to the SU camp saying that SU's can handle all the air needs of an L28 and therefore triple weber/mikuni's aren't needed. The Weber/Mikuni guys saying there is lots more HP hidden that the triples bring out. So who is right? I am not in either camp at the moment but I would like to see the numbers, SU's are simple and easily maintained, triples look good and sound AWESOME but I don't want to s…
Last reply by LeonV, -
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I just rebuilt my triple Mikuni PHH 44s reinstalled and set the pilot screw to it's original setting of 1.25 turns out from bottom. The butter fly valves are completely closed and it will idle around 1000 RPM(ish) then it will idle right up to 2.5 to 3K RPM after a minute or so. That's with the starters turned off. If I play with the butter fly valve opening (idle set screw) and turn in the pilot screw to about 3/4 it seems to run but its rough. I haven't balanced it out yet. I'm trying to understand what's going on so a little direction on my misunderstandings would be great. My understanding is that the pilot screw adjusts the amount of air added to the mixture. …
Last reply by madkaw, -
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The little brass screw that connects the choke bracket to the nozzle was super tight - looks like I messed the screw head slightly. Might have to replace some dome and fuel bowl lid screws too. They're all brass screws I haven't seen before: for a flat screwdriver but what looks like slot for a phillips too. Are those available? British Classic Motors sells sets of SS bowl and top screws w/ socket head, don't know if they would fit the Hitachis but can ask them. Is SS OK or should they be brass? Seems like you could wreck the threads in the carbs with SS if you're not careful. Is there a carb screw size list anywhere? The carbs are rebuilt I guess (shiny new brass stuf…
Last reply by Oiluj, -
- 15 replies
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I normally set the needle valve closure point on carbs by blowing in the inlet and adjusting the tab so that the valve is shut at 90 degree point of swing (top of float is parallel to top of fuel bowl). The carbs I have set like this have always worked fine. However, I ran into some problems today with a set I did this fuel level technique too so I decided to check in more detail as I could not get the A/F ratio to work no matter what I did with the jet height. I decided it was best to back track and recheck every thing. I first tried adjusting the fuel level at 23mm in the bowl and also the other technique of meniscus 10 turns of the jet down the well. The carbs initial…
Last reply by Captain Obvious, -
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After a drive, checked the clear filter before the mech pump while the car was idleing - only about 1/8 or less full. Looked at it carefully and could see bubbles appearantly being drawn into the fuel pump. It's installed so it sits level, horizontally. Tried tilting the filter (due to the hoses I could only tilt it about 45 deg both ways). When I tilted it the filter started filling up. Within about 45 seconds it was filled up about 5/8 to 3/4 full and no bubbles. Put it level again. Slowly (took about 3 minutes) the level went down to almost empty. Repeated the test 3 times - same result every time. Doesn't seem to matter which end is tilted up. WTF? Have been having…
Last reply by Stanley,
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