Laurel1800 Posted July 28, 2012 Share Posted July 28, 2012 Is there a guide for this somewere? I have a 510 with twin 260z roundtop carbs and it is running rich, i dont want that so i need to find out how i can fix this. Quote Link to comment Share on other sites More sharing options...
Sealik Posted July 28, 2012 Share Posted July 28, 2012 (edited) Is there a guide for this somewere? I have a 510 with twin 260z roundtop carbs and it is running rich, i dont want that so i need to find out how i can fix this. These might help... http://www.zcarz.us/TechnicalInformationPageCarburation.htm http://www.jetlink.net/~okayfine/sutech.html Size of engine??? What needles are you running? Running rich at just idle...or....? Wide band A/F ratio gauge is rather handy when setting up SUs Edited July 28, 2012 by Sealik Quote Link to comment Share on other sites More sharing options...
Laurel1800 Posted July 28, 2012 Author Share Posted July 28, 2012 Thanks for the links, that looks like i could learn from it. 1800cc engine, stock needles i guess, my spark plugs are black and the oil on my dipstick smell like fuell. Dont know if it is rich at idle or when driving. Quote Link to comment Share on other sites More sharing options...
Sealik Posted July 28, 2012 Share Posted July 28, 2012 Well...you have to pull a needle to determine size. You definitely need a fatter needles....but the 46s(?) might be a little to much for the 1800..?..38s would be a better 'fit'. I've got a LZ23/240Z 46mm SUs with RA needles and it runs a little rich at idle and WOT...cruising is good though, between 14-16 I have a wideband to monitor A/F ratios , somewhat simplifies 'searching' for the appropriate needles Quote Link to comment Share on other sites More sharing options...
Laurel1800 Posted July 29, 2012 Author Share Posted July 29, 2012 but these carbs are on the bluebird from the factory so why should i change needles? Quote Link to comment Share on other sites More sharing options...
Tony D Posted July 29, 2012 Share Posted July 29, 2012 If you have "Roundtops from a 260Z" then they are NOT and NEVER WERE on an SSS1800 engine. As stated above, they MAY be 38mm and not the 46mm as on 260's and 240's. In fact, NO 260Z anywhere came with "round tops"---in Holland they also came with the "Flat Tops" and the air bypasses were sealed. Figure out what EXACTLY you have, and THEN start figuring out what to do. I'd verify bore size FIRSTLY. If they are 38mm and not 46, then they are "SSS" SU Carburettors, and then any 510 Forum or SSS Bluebird Forum (Ratsun.net for example) will have LOADS of engine-specific information on them. They were not universal between the 4 and 6 cylinder applications. They were different! Quote Link to comment Share on other sites More sharing options...
Laurel1800 Posted July 29, 2012 Author Share Posted July 29, 2012 (edited) Well here's a pic of what they look like: they are round, but flat. I have no idea about their sizes. I posted the same pic on ratsun, they say these are hitachi sidedrafts, no needles. You could check with a brit, they know how to tune an SU in the dark fog w/o a torch. We are not very familiar with them here, as they only came on the 1969-1974 Z-car. Is what they said on ratsun forums. So they are similar to 240Z carbs then? Edited July 29, 2012 by Laurel1800 Quote Link to comment Share on other sites More sharing options...
morbias Posted July 29, 2012 Share Posted July 29, 2012 Those are flat tops... the tops are flat Quote Link to comment Share on other sites More sharing options...
Tony D Posted August 4, 2012 Share Posted August 4, 2012 38mm Late Model Hitachi SU's and "they" are wrong. The Hitachi licensed SU Flat-Tops HAVE needles same as all of them. And they adjust JUST like the earlier round-tops. They are not like SU HIF6's that they were patterned after in the 46mm version. They ARE NOT '260Z Flat Tops'---there is gross ignorance about non-us specification (and quite a bit of ignorance about us-specification) equipment on these items. These are late model SSS Carbs. Virtually identical to the early carbs with the difference being the ability to idle on a separate dedicated circuit, allowing for a 'fatter' (richer) main needle cut. Chances are if you are adjusting them like a set of Round Tops, you have them all wrong. Follow the guidelines in the 260Z manual for setting up the idle circuit using the external screws, and set the main and transition on the jet position under the carbs (like you would with a real HIF-6, but without the easy screwdriver adjustment of the needle / jet relationship) similar to the earlier 240Z/1600SSS Carbies. This is a piece of cake, but you can't listen to idiots who don't know what you have and give you bad advice. I had a set of these on my 2L Fairlady Z for years. When I sold the car, I kept them, and transferred them to an L20B (instead of using early 1600SSS Round Tops, or later 1800SSS Flat Tops)---ran great! Looked identical to the 1800SSS carbs, so other than the double bolt up front on the timing cover...nobody was the wiser watching my Estate Car pull away! Ratsun I was hoping would be more enlightened. The 510 Forums have extensive stuff on setting up the SSS Carbs, including some good diagrams to figure out the vacuum hoses for the later carb setup. But the ignorance regarding the 'Flat Tops' persists, even though the carbs are functionally identical to the earlier units, save for a separation of idle circuits so you don't have to run pig rich at idle (or lean at idle) and vice-versa on the powerband. This single modification made the SU carburettor suitable for use WELL into the 1980's and was used by Honda that late (even in the US and California Emissions Markets!) Luddites, what can you do with them? (Answer: Stuff them in a Big Straw Man and light it on fire...) Cheers! Quote Link to comment Share on other sites More sharing options...
Laurel1800 Posted August 4, 2012 Author Share Posted August 4, 2012 Thanks Thats info i can work with I took them aparft and cleaned them out, that fixed a lot of the problem, now some fine adjustments and i guess they are good to go. Quote Link to comment Share on other sites More sharing options...
Tony D Posted August 6, 2012 Share Posted August 6, 2012 All I needed was a photo to see what it was. 73 240Z & all 260Z 46mm carbs have a choke plate in them with a squarish intake end. If they are round, and flat top, they are 38's! Go to Frank's Barn outside Amsterdam if you want to see 46mm Flat Tops from the Dutch Market (if you get there after I do, they may not be there any longer!) Quote Link to comment Share on other sites More sharing options...
Laurel1800 Posted August 6, 2012 Author Share Posted August 6, 2012 Whats Franks Barn? Quote Link to comment Share on other sites More sharing options...
Tony D Posted August 6, 2012 Share Posted August 6, 2012 It's this place outside of Amsterdam...surrounded by sheep that look at you 'come hither' and it's filled with Z's... Quote Link to comment Share on other sites More sharing options...
Laurel1800 Posted August 6, 2012 Author Share Posted August 6, 2012 Seriously? I have never heard of it and you know about it? I need to go there too now i know of it beinig there somewere. Quote Link to comment Share on other sites More sharing options...
Tony D Posted August 8, 2012 Share Posted August 8, 2012 Past the McDonalds, on the right, surrounded by sheep. Out in the Barn, preserved...or used... are things... Now, you Dutch and your Bike Fetish, but back to the barn. There are things. Unnatural Things... Natural Things... Fetching Things that say "Come Hither!" But then play Hard-To-Get! The Barn Exists there, trust these two, they wouldn't lie! I shall return, likely in late September for a trip to the barn, and places nearby... For there is more than one... You must watch the signs on the roadside, the barns are everywhere! You just need to find the right person to reveal them! King Frank, in his "receiving guests regalia" before a foray to 'Das Barn' Quote Link to comment Share on other sites More sharing options...
Laurel1800 Posted August 8, 2012 Author Share Posted August 8, 2012 well, i think i must see the inside of this barn filled with Z's too Quote Link to comment Share on other sites More sharing options...
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