kristinynacho889 Posted October 8, 2012 Report Share Posted October 8, 2012 i have SU carbs they work i just never can get them to idle right! i would post pictures but i dont know how asking $275 polish monifold and top bowl!pm me for more info thanks!! Link to comment
datzenmike Posted October 8, 2012 Report Share Posted October 8, 2012 http://community.ratsun.net/topic/691-how-to-post-pictures-and-keep-online-photo-albums/ 1 Link to comment
ggzilla Posted October 8, 2012 Report Share Posted October 8, 2012 Size? Are they the 38mm units or 46mm? Link to comment
kristinynacho889 Posted October 9, 2012 Author Report Share Posted October 9, 2012 i think there the 38mm there smaller than the ones i have on my L20 but not sure they work good i just never got them to idle but long story shorth i had a bad distributor so it wasnt even the carbs it was my timing all the time!! Link to comment
Just Joel Posted October 9, 2012 Report Share Posted October 9, 2012 Post pics, we can help you id then... tough sell based on nothing but this description ;) Joel Link to comment
kristinynacho889 Posted October 9, 2012 Author Report Share Posted October 9, 2012 got some pics up!! Link to comment
2JZ260z Posted October 10, 2012 Report Share Posted October 10, 2012 Look like flattops to me Link to comment
ggzilla Posted October 10, 2012 Report Share Posted October 10, 2012 Yes from the new photo they are Hitachis. I can see the Hitachi icon on them. Flat-tops which are superior, but they are missing the idle mixture hoses so it is a wash. Look like 38mm units, a bit small for a 2-liter engine, but perfect for a 1.6 liter engine. Link to comment
wayno Posted October 10, 2012 Report Share Posted October 10, 2012 Yes from the new photo they are Hitachis. I can see the Hitachi icon on them. Flat-tops which are superior, but they are missing the idle mixture hoses so it is a wash. Look like 38mm units, a bit small for a 2-liter engine, but perfect for a 1.6 liter engine. What are idle mixture hoses? I have 38mm carbs on my LZ23, and it runs fine. Link to comment
kristinynacho889 Posted October 10, 2012 Author Report Share Posted October 10, 2012 wen i had them on the ran fine on my L20 i really dont know much about them but they worked fine i just got biger ones now and fix my distributor!! l Link to comment
ggzilla Posted October 10, 2012 Report Share Posted October 10, 2012 The 38mm dome-tops don't use all the hoses and adjusments The 38mm flat-tops do. But without them it is not superior to the flat-top. Yes, it will work OK. Link to comment
wayno Posted October 10, 2012 Report Share Posted October 10, 2012 The 38mm dome-tops don't use all the hoses and adjusments The 38mm flat-tops do. But without them it is not superior to the flat-top. Yes, it will work OK. I have a set of flat-tops also, they were a smog type carb, all the smog stuff had been removed and block off plates installed, would that have also make them basicly dome-tops? Link to comment
ggzilla Posted October 10, 2012 Report Share Posted October 10, 2012 38mm flat-tops are not "smog" carbs. You might be thinking of the 260Z 46mm flat-top carbs. 38mm flat-tops have a superior idle and mixture control. But it requires all the parts. Otherwise you get the basic control similar to the old dome-tops. Which will work OK ... Link to comment
wayno Posted October 10, 2012 Report Share Posted October 10, 2012 38mm flat-tops are not "smog" carbs. You might be thinking of the 260Z 46mm flat-top carbs. 38mm flat-tops have a superior idle and mixture control. But it requires all the parts. Otherwise you get the basic control similar to the old dome-tops. Which will work OK ... So what are these? They are 38mm, they are flat tops, they have 2 mount holes, and the smog parts have been deleted by plates. Link to comment
ggzilla Posted October 10, 2012 Report Share Posted October 10, 2012 They look like Hitachi 38mm flat-tops. The plates block off the IMS parts (Idle Mixture System). The ones for sale here probably do have all the IMS stuff, except for the hose to the air cleaner. Not sure how all those hoses work. Link to comment
datzenmike Posted October 10, 2012 Report Share Posted October 10, 2012 Mine came with I imagine the bottom two connect and the top one on the left goes to the air filter. There's a write up for removing them like what Wayno has. I was under the assumption that this was a smog related thing and it ran better removed??? From the SU Tech Page.... Desmogging Topical information provided by Jason Gray As I said at the top of this page, the flat-top SUs were imported carbs bolted to imported L18SSS motors. If your set of flat-tops have ever been run in the States, they probably have had the smog equipment fittings removed already. If this is the case you'll find a small, triangular aluminum plate screwed in place just behind each dome/tuna can. If so, then your flat-top SUs are desmogged and are the functional equivalent of dome-top carbs. They're just a little more art-deco in style. However, if you find a triangular plate with hose connections/pipes pointing upward, then your carbs have not yet been desmogged. (a third alternative is that you have nothing covering the holes in the SU bases, in which case just follow along) A third piece of smog equipment is the hose connection/nipple screwed into the balancing tube in the middle of the manifold. Refer to the Nissan Motorsports Schematic diagrams of the SSS SUs to visually see what needs to go. The only hose connection you need for the carbs to perform properly is the distributor vaccum advance that is pipped off the front carb. (Look on the float-bowl side of the front carb and there will be a small vacuum port. Connect this to your distributor when you bolt the carbs onto the motor.) The hose connections were connected to various devices in order to control emissions. Remember when you had to run hoses and backfire valves around your engine compartment every smog check? Well, same sort of deal. Desmog I: Remove the triangular plate with the hose connections from each carb body. There are three screws that attach each plate. Use some thin (1/8" is fine) aluminum (aluminum is easiest to work with, you could use steel if that's what you have handy) to make block-off plates. Use the triangular pieces you removed as templates for your new parts. Cut out the aluminum plates. Drill holes to match (again using the pieces removed as templates). One of the screws on each carb body will protrude into the airflow if you use thin plate material. You can cut down two screws (measure twice, cut once) to use in those positions. Using gasket paper, cut out two gaskets for your new block-off plates. The last thing you need is a vacuum leak. Apply some Permatex/gasket goo to both sides of the gaskets you just made and set them in place on the SU carb bodies. Place your block-off plates on top and screw them down. Locate the extra hose connection located on the balance tube in the middle of the manifold. Find a bolt with the same thread pitch and thread it in place of the nipple. Alternatively you can cut off the nipple section of the part and fill in the hole with JB Weld, or the like. Desmog II: Another method to blocking off the emissions passageways is to fill the holes with JB Weld. You'll want to seal the carb bore with tape so the epoxy doesn't drip inside and get in the way of the throttle plate. After it is dry, sand away any protruding mess on the top of the carbs. It doesn't really say what the hoses do. Maybe it functions as the idle air supply?? .... Flat-tops which are superior, but they are missing the idle mixture hoses so it is a wash. ggzilla do you have any input as to what exactly these hoses are for? . Link to comment
ggzilla Posted October 11, 2012 Report Share Posted October 11, 2012 They are not "smog" parts -- irregardless of what a 30 year old article says. They are the Idle Mixture System. You can adjust the idle mixture, similar to a Weber carburetor. With the Dome-tops there is a different adjustment for this via the SU-style "nut". The carbs for sale here are nice units, with polished bowls. Don't be afraid of 38mm flat-tops. The only question is exactly how to connect and adjust, since the manuals are in Japanese. Seems there is no writeup in English about it. But I think it has all the hoses, you turn the screw to adjust the mixture, seems to work good. Link to comment
datzenmike Posted October 11, 2012 Report Share Posted October 11, 2012 Good to know. I haven't touched mine. Link to comment
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