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Just wanted to let you all know that on my old l24 i was getting about 15mpg. Then i swapped in a new l28 with triples, was getting about 13mpg. Took the webers off and put on SU's. Then it was getting about 22mpg. I recently bought a set of SM needles and the just su's video. I thought i knew all there was to tuning these things. Boy was i wrong. Im now getting 27mpg mixed city/hwy, and shes as fast as ever. Bitchin!
 

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Ben240, please give me your opinion on which is the best performance and fuel-saving needle to the SUs if I will be using my 240 just for street/daily driver? When I repair my SUs, how can I tell which needle I already have.? I have the "Just SUs" Video. Thanks, Ernest (240/260Z)
 

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The numbers for the needle are either stamped or printed on the fat part of the shank of the needle. If you are lucky you can still read them. Sometimes the stamped numbers will have been cleaned off with solvent. You may need a strong magnifier to read the ID (depending on how old or young your eyes are). I have caliper measurements on N27 and SM needles if you need them. Still looking for someone to donate there N54 or other old needles for measurements. Also you might look into downloading the 'Haystack' SU needle program and get the book 'How to Build and Powertune SU Carb" if you want to really get into it.
 

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Yeah my old needles must have been printed, there was no way to identify them. As to which needles are best, it all depends on the motor. On my stock l28 with su's, the sm's work much better than the stock 72 needles, whatever those may be. They were a bit lean, my engine ran hot and detonated a little. Like i said, im getting better mileage and roughly same power with the SMs as the old ones. I know the sm's arent the perfect needle, but they are close enough for me. Pick whatever runs best on your motor, and take your time tuning. You wont be disappointed.
 

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Yeah I just love my SU's!!! I am good with my hands but don't know the tech stuff on cars and after getting help here from Norm , Scott (and his Video!!) and many others here I was able to learn how to tear them down on the car totally clean then reassemble and now I have them tuned to the point my plugs still are new looking (even got off the carbon that I got before i had them totally dialed in ..) and the throttle response is sweet!!!

JohnH where is that file you mentioned?? I would be interested in that one and possibly the book too.. I am doing a couple of new things to the fuel/ intake system now..

Also here is one for anyone.....
I pulled my domes off the other day and was just looking and thinking and I put some of that silver antiseize on the throttle body (well the chamber whatever) and then I put the piston back in and dropped the dome on and pushed up the piston and let it go a couple of times....
Then I took it apart again and it left a very nice marking on the piston of where the piston was rubbing...Now would it be beneficial to polish down these areas so that there is no drag on the piston or will it not really matter due to the forces when the car is running? Could it possibly give better response?


Z ya later
Mike K
 
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