QUOTE VaGuS510

"You could try to use a .99 nozzle. If you think you are running rich everywhere then this should lean you out everywhere.

I just installed some O2 sensors on my car and i got a nifty gauge that reads both o2 sensors at the same time. I also am going to need a richer needle. I am currently rich at idle and cruise but it leans out big time when i get on it. The only way to keep it from backfiring is to make it run really rich at idle and cruise. Therefor i get bad gas milage, about 10 mpg. I am currently running N54s on my L28. I am also leaning towards trying an SM needle as a baseline..."

Vagus:

Isn't the N54 stock for the SU? If so and you use a 2.8l block, I would not be surprised you run lean at WOT. I'm no SU expert by any stretch, but surely increasing displacement without changing needle diameter would cause a lean condition, yes?

BTW, I looked for N27 needles and couldn't find anything...can you fill me in?

Lastly, do you know of a source to buy additional needles? Checked your Teglerizer link (very nice), but they don't look like a retailer.

Thanks,

Steve

I like all this, makes lots of sense. But where can we find the station specs of the N54 and N27 needles to compare with? The linked sites don't have the Japanese needles listed.

Also, my car has an '83 280ZX 2.8 in it. I'm putting SUs back on it, but I can leave the O2 sensor in it. Any one know if there's a way to get a reading of some sort from the factory O2 sensor?

Let's get this right fellas. Z's use HITACHIs not SUs. Very, very similar but HITACHIs just the same.

what are you talking about Nigel? Datsuns have SUs ...Hitachi bought the rights to reproduce them...they are SU's...you can put them on an mg if you wanted to, you can put british SU parts on them....they are SUs.

Hitachi built them, but they are SU's built under license from SU.

what are you talking about Nigel? Datsuns have SUs ...Hitachi bought the rights to reproduce them...they are SU's...you can put them on an mg if you wanted to, you can put british SU parts on them....they are SUs.

Catergorically not british SU's! Agreed Hitachi produced them under licence and yes, they can be fitted to MG's et al because they were designed around the british HS4 SU with Hitachi's own modifications, especially in the mixture adjustment department. There are very few interchangeable parts aside from the needles.

First of all pull the SM needles and use them for a dart board. Go with 54s or if you are running a 280 try 27s . The SM needles are too rich for any Z eingine under 3K stroker. The leaner needles will make more HP and better mileage and wont contaminate the oil in the pan with unburned fuel. The color tune is not lying to you , you are running vary RICH . If you want more informaion send me a PM with your email address and I will forward some info from some engine builders that race Zs that tried the SMs needles. The roller bearings can carbon up and stick the shaft , which can cause a problem if you are going into a corner at hispeed after a wide open throttle aproach down a stright. How many times have you had your car pop back through the carbs ? When this happens carbon particles blow out under pressure , hellow. Some thing to think about . :sick:

Kim Blough says the same thing about SM needles. Also the roller bearings are in the old original Z Therapy carbs, the don't use them anymore.

what are you talking about Nigel? Datsuns have SUs ...Hitachi bought the rights to reproduce them...they are SU's...you can put them on an mg if you wanted to, you can put british SU parts on them....they are SUs.

dogma, if you leave your Z like that much longer....it will stay like that permanently. Didn't your mother ever tell you?

I'm not sure what all the reference about the roller bearings is saying, but I just want to pass on the fact that we are still using bearings. They are a far superior design to what the former owner used, but are bearings none the less.

We are also having a write up put together highlighting results of needle comparisons done on Steve's Z last summer. Been in the hands of an engineering student at Oregon State for compilation but he keeps saying something about school work getting in the way...................... Now if we could just get this data aquisition equipment to write a report....

Kim Blough says the same thing about SM needles. Also the roller bearings are in the old original Z Therapy carbs, the don't use them anymore.

I'm not certain which needles are in my soon-to-be-installed carbs, but I suspect that they are whatever was stock for the 70-71 4 screw carbs (N54s?) I plan to use them on my L28, and won't change unless they are demonstrably lean.

ZTherapy still says they use roller bearings, but that their bearings are "double-sealed." I assume that means they have an inside seal that would prevent carbon from getting in the bearing from the inside, as well as stuff coming in from the outside. I don't have any myself, so I obviously can't speak from experience.

Sorry my bad, I believe that I read somewhere that Z Therapy went to bushings.

Arne, I've always liked that light green color.

Arne, I've always liked that light green color.

Gotta do something about that pic. The car is really #919 yellow.