stevo_gj Posted December 25, 2008 Share Posted December 25, 2008 Hey guys, I've recently purchased a pair of 240z SU carbys to clean and use to replace my flat top 260z carbys. My engine is a stock L26. The SUs are in fairly good condition and I really only intend to replace the gaskets, but a few people have suggested that I look into SM Needles. I have searched hybridz trying to learn more about SM needles, but so far I have only found that they are not ideal to be running on an L24, but are perfect for an L28. No one has mentioned how they perform on an L26. The needles on the SUs seem to be in good condition, but I wouldn't remind replacing them with these SM needles if there really is a power boost. What do you guys think? Merry Christmas, Steve Quote Link to comment Share on other sites More sharing options...
2fast2Z Posted December 25, 2008 Share Posted December 25, 2008 I'm not sure if this is right but i have read someplace that using the needles from the flat top in a set of round top should be an improvment, you have the parts so why not try it. Chris Quote Link to comment Share on other sites More sharing options...
stevo_gj Posted December 25, 2008 Author Share Posted December 25, 2008 I've never heard of that before! I'd be interested to hear more, and also anyones comments on the SM needles Quote Link to comment Share on other sites More sharing options...
Xnke Posted December 25, 2008 Share Posted December 25, 2008 The SM needles are widely regarded as too rich by many on this forum, for even a stock L28. The original N54 needles are fine for the L26, and even good for the L28 too, as long as the carbs are set up right. Start with the N54 needles, and if you need more fuel (use a good wideband to determine this) then look into the british SU needles for something between the N54 and the SM. Quote Link to comment Share on other sites More sharing options...
Firepower Posted December 25, 2017 Share Posted December 25, 2017 On 12/25/2008 at 6:17 PM, Xnke said: The SM needles are widely regarded as too rich by many on this forum, for even a stock L28. The original N54 needles are fine for the L26, and even good for the L28 too, as long as the carbs are set up right. Start with the N54 needles, and if you need more fuel (use a good wideband to determine this) then look into the british SU needles for something between the N54 and the SM. +1 SM Needles didnt work well for me on a 260z L26 engine with rebuilt dome top carbs. Far too rich at idle, and if you lean down to get that right- the top end beyond 2600 RPM suffers. I’m happier with the N57 needles and the carbys synched with a meter and fuel/mixture set by the lift piston methods, and then a colour-tune. Wants to get up and go now, fuel economy is better tham with SMs. Plus - my eyes dont water from a fat fuel/air mixture. Quote Link to comment Share on other sites More sharing options...
Mixelplix Posted January 2, 2018 Share Posted January 2, 2018 When I had my 3 screw SU's redone by Z Therapy he indicated that the 240z needles work best with the L26's. Take that for what it's worth. Quote Link to comment Share on other sites More sharing options...
Firepower Posted January 3, 2022 Share Posted January 3, 2022 For anyone interested… I have a ‘73 240Z but with a 260Z engine. Rebuilt E88 Head, new valves etc…. I got dome top SUs rebuilt by ZTherapy. They supplied SMs as part of the deal. After messing around a lot, I went back to N57s - closer to stock 240Z needles. After doing sone research & looking into it, today I just ordered a pair of BC needles. I could post specs and differences if anyone has an opinion on this move. I think this car had twin HS6 SUs: AUSTIN HEALEY 3000 BJ7 ORIGINAL SU METERING NEEDLES: 'BC' -Richard Quote Link to comment Share on other sites More sharing options...
Firepower Posted January 3, 2022 Share Posted January 3, 2022 (edited) 6 hours ago, Firepower said: For anyone interested… I have a ‘73 240Z but with a 260Z engine. Rebuilt E88 Head, new valves etc…. I got dome top SUs rebuilt by ZTherapy. They supplied SMs as part of the deal. After messing around a lot, I went back to N57s - closer to stock 240Z needles. After doing sone research & looking into it, today I just ordered a pair of BC needles. I could post specs and differences if anyone has an opinion on this move. I think this car had twin HS6 SUs: AUSTIN HEALEY 3000 BJ7 ORIGINAL SU METERING NEEDLES: 'BC' -Richard I’m just using a butt dyno and going on feel of how the car accelerates and cruises on the freeway. Any comments appreciated. Edited January 4, 2022 by Firepower Updated Data & Graphs (enlarged) Quote Link to comment Share on other sites More sharing options...
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