james Posted February 28, 2000 Share #1 Posted February 28, 2000 I am restoring a '73 with the SU flattop carburetors. The car has been garaged for 18 years. I have the engine running but the rear carbuetor is running very rich, the front carb is o.k.However,since there is only the one mixture adjusting screw on the front carburetor I am uncertain as to how to correct this. any ideas? Link to comment https://www.classiczcars.com/topic/370-hitachi-flattops/ Share on other sites More sharing options...
Mike Posted February 29, 2000 Share #2 Posted February 29, 2000 James,This question is more suitable for the Z-Car Operations area of the forums. I have moved it to that location. It's inside the Carburetion forum.[m] Link to comment https://www.classiczcars.com/topic/370-hitachi-flattops/#findComment-764 Share on other sites More sharing options...
Mike Posted February 29, 2000 Share #3 Posted February 29, 2000 I am unfamiliar with the flattops. I have the rounttop SU's. But, the mixture settings are controlled on my rounttops from the bottom. The mixture nuts are difficult to get to, but they are located where the small fuel tube enters the bottom of the carburetor. If you are looking up at the bottom of the carburetor screw... Tightening (righty-tighty -- lefty-loosen rule applies) it will send LESS fuel to the carb. I'm assuming you probably know that. But, hopefully my information about the location of the fuel mixture is correct. The adjustment screws on the top of the carbs control the airflow (balance and volume). [m] [This message has been edited by Mike (edited 02-28-2000).] Link to comment https://www.classiczcars.com/topic/370-hitachi-flattops/#findComment-765 Share on other sites More sharing options...
71 240z Posted July 6, 2000 Share #4 Posted July 6, 2000 James,The flat top carbs you have are reallya pita! I have worked on them in the past with mixed results. You are correct in the mixture adjustment is on top and only one nut to turn. If your reaer carb is running rich, the only way to correct is to attempt to rebuild this carb. The design on this carb put the flost chamber on the bottom of the carb where the floats "cooked" due the heat from the exhaust. Check which floats you have as there are two different styles and you must replace floats to have any chance. Better bet is to contact Scott @ Ztherapy.com and change the carbs to the early style.Richard 71 240Z73 240Z(totaled) Link to comment https://www.classiczcars.com/topic/370-hitachi-flattops/#findComment-766 Share on other sites More sharing options...
Bambikiller240 Posted July 7, 2000 Share #5 Posted July 7, 2000 James: Use the 1973 carbs for boat anchors, thats about all they are good for!!! ;-)I concur on the suggestion to check out Scott's Round Top SU's at ZTherapy.com. I saw many of these units on the finer cars at the MSA show in April. NO ONE had a bad thing to say about these beauties! I'll have a set for my car as soon as I complete the current work on my car and pay off the parts bill! :-)------------------Carl Stahlnecker72 240Z "Bambikiller"HLS30-55703 11/71cstahlnecker@hotmail.combambikiller240@altavista.com Link to comment https://www.classiczcars.com/topic/370-hitachi-flattops/#findComment-767 Share on other sites More sharing options...
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