Sorry guys I been reading on the SU and I cant seem to find it or didnt recognize it but here is my question.

I have a L28 engine on my 73z and I had tripple carbs but Im converting back to SU

Will the Su work and if so what do I need to do to make it work for a higher liter engine?

Im just tired of tripple weber carbs and they are very sensitive that I keep adjusting. I just want SU now and I dont race so its a waste to even have tripple webers if im just dailing driving it.

I like having good gas milage as well and tripples dont do that for me.

Thanks everyone for being patient with me and answering my question on this. Really appreciate it

I had an L28 EFI engine in my '73 240Z that had the stock 240Z SUs fitted to it.

They worked very well and the engine responded excellently:)

I don't believe you will have to modify the carbs. at all, just make sure the fuel supply pressure is correct and use a fuel return line to avoid vapour lock in hot weather.

They will work fine. We have had 2 different Zs with 2.8 engines with our standard production carbs holding hillclimb records locally.

If you get 'em on and running and they are lean you might want to throw a set of SM needles at them.....

SM needles may be too rich, depending on the rest of the engine mods and your altitude. Of course, if you were running triples, the engine may be able to use the richer mixture of the SM needles.

I know several people with SUs on L28s, beandip is one. Seem to work great.

You guys are great. I really appreciated it.

SM needles? Ill take a look at those.

I really love this car club. Alot you guys have been very helpfuly.

Is there a site for these SM needles and how big do I have to go?

Im running a mild cam on my engine but nothing major after that

Edited June 6, 200915 yr by myfairlady

We should see if we can get Gary (beandip) to chime in. He has an L28 with P79 head and a mild cam and header, found the SMs were too rich for his setup. Can't remember what he ended up running, I think it was the needles for a '70, which were the richest of the stock 240Z needles.

I am indeed running SUs on a ZX motor as Arne stated. The compression is at 9.5 to one . Not high but higher than stock. When I installed this engine I thought because of the headers , Cam and larger displacement I may need richer needles . I tried the SMs and they caused the mileage to tank and were so rich that I was getting gas in the oil . I tried the 47s I think that is the number. In any event the ones for the '70Z that Arne mentioned and again vary rich. I went back to the needles that I was running on the L-24 Motor and she runs well . I tried 58s also, too lean. I bought a new set of 54s and have been running them for 8years +. Good torque all through the power band. Mileage is good too and I can run regular gas but use the midrange gas. Aside from the good performance. I took the Z to the Emissions center , DEQ here in Or. and the car passed emission testing. '73 is exempted but since it was a free test I thought I would do it for me. I have zero emissions equipment on the car.

Gary

Edited June 6, 200915 yr by beandip
spelling

I am indeed running SUs on a ZX motor as Arne stated. The compression is at 9.5 to one . Not high but higher than stock. When I installed this engine I thought because of the headers , Cam and larger displacement I may need richer needles . I tried the SMs and they caused the mileage to tank and were so rich that I was getting gas in the oil . I tried the 47s I think that is the number. In any event the ones for the '70Z that Arne mentioned and again vary rich. I went back to the needles that I was running on the L-24 Motor and she runs well . I tried 58s also, too lean. I bought a new set of 54s and have been running them for 8years +. Good torque all through the power band. Mileage is good too and I can run regular gas but use the midrange gas. Aside from the good performance. I took the Z to the Emissions center , DEQ here in Or. and the car passed emission testing. '73 is exempted but since it was a free test I thought I would do it for me. I have zero emissions equipment on the car.

Gary

Beandip.

Thanks for all the info. Your lucky there is no emissions in your state. In my state even though its a 73 it has to be a 68 to have no smog. Suck especially when I had tripple carbs but cause of the info on the SU's Its going to be worry free for me now. Mid grade huh? awesome. I been running high oct cause the tripples are picky.

So 54 is the stock needles for these carbs? The carbs im getting is from a l24.

Im running a mild cam and a 6 to headers so these carbs are great for the spec I have now.

Thanks alot everyone I cant stress enough how you guys are helping me out and really appreciate it

The story on the SM needles is as follows: In the 7-73 book "How to modify Datsun engines and chassis" the SMs were installed as part of the first step up in performance tweaking. They tend to overcome what some believe to be a lean condition in the stock needles (some being worse than others).....

As has been stated here, getting one needle or another to run well seems to be engine dependent....

I will be getting my carbs in two weeks. If I need the sm needs where do I get it?

I got SM needles from ztherapy.com 3 years ago works well on my L28,

check Bruce Palmer signature on previous reply

Does your engine have any other modifications, or is it basically a stock L28?

I'm running modified original SU carbs on my car and don't have any complaints. Mine is a F54 on the bottom with a ported and polished P79 on top. I opted to get some more flow through the 'ole SU's.

I sent them to Rebello and had the carbs overbored with custom tapered needles made for my application. After I got them back it was a simple bolt on affair. The only adjustments I had to perform were airflow syncing and hooking up my wideband O2 sensor to dial in the A/F mixture to optimal. They have worked great ever since.

Edited June 8, 200915 yr by blue 72