Dantheman Posted January 19, 2014 Report Share Posted January 19, 2014 I have ended up with two sets of carbs. As titled one of each type. I only need one set and don't know which is the set to keep and reasons for favoring one over the other. I hope this question is not too basic as I have no knowledge of these. My project is slow going but I try to get parts when I find what I think is a good deal. Future plans are for a 2.3 LZ. with a more vintage sss look. Thanks. Quote Link to comment
datzenmike Posted January 19, 2014 Report Share Posted January 19, 2014 If the 38mm ones they are for L16/18 and ones as good as the other AFAIK or an concerned. The flattops do have to be 'de smogged' though. Simple as some JB Weld.The square mouth 46mm L26 flattops are not to be confused with then. Only once heard anything good about them. Back in the day Nissan mechanics hated working on them. Even the factory couldn't get them to work for long.ZTherapy 240Z SU Carburetor Spotter's GuideThis is not a carb-It is a boat anchor!June1972 240Z to all 260Z's (US) Flattop "Hitachi"Evil things, these square mouthed carbs.If you have these carbs on your 240Z-trash them and get ZTherapy SU's. You will experience a huge increase of power, mileage, and less breakdowns!These are commonly referred to as "Hitachi's" or "Flattops". The dome shoulder is square, and the float bowl is on the bottom.These carbs are not acceptable as cores. Please pay the core charge instead of sending these in. Quote Link to comment
Kirden Posted January 19, 2014 Report Share Posted January 19, 2014 According to Z therapy, you want the domes. There are rumors going around that with correct tuning flats can be amazing, but Z therapy says they are trash. They won't even accept them as cores. http://www.ztherapy.com/technical_stuff/spotterguides/zcar/240spotter.htm Edit: looks like if they are flats and square port they are trash, other flats may be ok? If you can, call Z therapy and ask them. Quote Link to comment
datzenmike Posted January 19, 2014 Report Share Posted January 19, 2014 What I heard too. They flow more air but are extremely problematic. Quote Link to comment
Sealik Posted January 19, 2014 Report Share Posted January 19, 2014 If you're building an LZ23 I would go with the early Z 46mm SUs (round tops) and the larger K14 intake...port everything to match 1 Quote Link to comment
datzenmike Posted January 19, 2014 Report Share Posted January 19, 2014 I agree. 38s will support L16/18 but be closer for an L20B than 46s. If above a 2.0 liter like an LZ2.2 or 2.3 definitely look at the 46s Quote Link to comment
Dantheman Posted January 19, 2014 Author Report Share Posted January 19, 2014 Thanks guys. I did speak with a guy at Ztheroply last week and was told that the flats were ok. He has a wagon with a 2.3 and running 46mm. He think that the 38s would maybe be snappier around town but loose some at high rpms. Both sets I have are 38mm l4 set ups. The first set I bought on cl I was told are l18 sss flat tops and the second I got today at the Pamona Swap Meet. Early dome tops. Quote Link to comment
datzenmike Posted January 19, 2014 Report Share Posted January 19, 2014 FWIW I was told the very late L16SSS also got the flats as well as the L18SSS. Only the domes were on the L16. Take with grain of salt.... we didn't get these here. It's JDM yo. Quote Link to comment
Kirden Posted January 19, 2014 Report Share Posted January 19, 2014 If that's the case you could go with a low RPM range cam grind and be all set. Schnieder has a .480 lift that goes from 2200-6400 and a .460 for 2500-6600 so there are options for a nice city cruiser :) Quote Link to comment
datzenmike Posted January 19, 2014 Report Share Posted January 19, 2014 0.480" is very close to binding the stock springs. Banzai Hainz will know about this. Also see Sealick's thread about tapering the SU's needles to richen up the high RPM lean out. Quote Link to comment
Dantheman Posted January 19, 2014 Author Report Share Posted January 19, 2014 So it sounds like the 38mm will be ok and as far as the flat vs round? Quote Link to comment
Son_of_a_Datsun_Guy Posted January 19, 2014 Report Share Posted January 19, 2014 Round top, they're the non smog version. I've also been told (by Bruce and Steve at Z Therapy) that the 46mm aren't really necessary, even on an l20B, I've got 38s on my 2.1 LZ and they work fine. I do have larger nozzles and a "fatter" needle that bump up the fuel quite a bit. Again, round top, much prettier 1 Quote Link to comment
Dantheman Posted January 19, 2014 Author Report Share Posted January 19, 2014 Thanks for the input son_of_a_datsun_guy. The picture of your set up is clean. Your work or sent out to Ztheropy? Quote Link to comment
Kirden Posted January 19, 2014 Report Share Posted January 19, 2014 I'd stick with the round top and hold on to the flats for parts or spares. If the high RPM fall off can be tuned out then there isn't really a reason to move to 46s so the 38 rounds would be your ticket. Just make sure they are in good shape and learn about tuning. I'm personally scared of SUs cause I don't understand tuning them (never taken one apart), but the great thing is they are pretty much set and forget. You hear way less horror stories about falling out of tune with SUs than you do with other sidedrafts. Quote Link to comment
Sealik Posted January 19, 2014 Report Share Posted January 19, 2014 I'd stick with the round top and hold on to the flats for parts or spares. If the high RPM fall off can be tuned out then there isn't really a reason to move to 46s so the 38 rounds would be your ticket. Just make sure they are in good shape and learn about tuning. All depends on how the engine is built. I have 46s on my LZ23 and get excellent mileage, have good A/F ratios, zero hesitation when I throttle it in the lower RPMs... and it's good for 6500+ VG DD Quote Link to comment
Dantheman Posted January 19, 2014 Author Report Share Posted January 19, 2014 Thanks Kirden, I also have heard good things about the su carbs. I did have a 1970 240z as a kid and the mechanic at the time said the parts needed to keep them synced were not available. I don't hear that anymore. Quote Link to comment
datzenmike Posted January 19, 2014 Report Share Posted January 19, 2014 All you have to do is plug these. Or remove and plug the covers. Quote Link to comment
Dantheman Posted January 19, 2014 Author Report Share Posted January 19, 2014 Thanks Sealick, did you buildyour LZ2.3 from the Jason Grey info? I'd be interested in what head and cam you are using. I am a ways off in time but like to start picking up parts. Quote Link to comment
Dantheman Posted January 19, 2014 Author Report Share Posted January 19, 2014 What difference is there in the 220 manifold and the K14 shown Mike? Quote Link to comment
Sealik Posted January 19, 2014 Report Share Posted January 19, 2014 Thanks Sealick, did you buildyour LZ2.3 from the Jason Grey info? I'd be interested in what head and cam you are using. I am a ways off in time but like to start picking up parts. Somewhat.....lol Z22 block bored to 89mm Z24 (NPR) pistons...shaved the small end of rods Shadbolt .491/260 Motorsports springs, 180-220 retainers, 180-190 lash pads. Rebuilt/Ported U67 head New timing chain assembly...etc. 4.38 gears/5 speed The K14 has larger intake ports than the 220 Quote Link to comment
datzenmike Posted January 19, 2014 Report Share Posted January 19, 2014 The K14 has larger intake ports than the 220 Hmm maybe that's a way to tell if off an L16 (220) and the L18 (K14) ??? Quote Link to comment
Dantheman Posted January 19, 2014 Author Report Share Posted January 19, 2014 What diameter is the intake port? And what kind of porting on the head. Did you increase size of the intake valves? I have an A87 with some work done. 1.5 intake with a peanut chamber that has been opened up. And the intake valves are increased to a 1.73in. I have been told that this head may not be worth doing anything with so not really sure yet. Quote Link to comment
Dantheman Posted January 19, 2014 Author Report Share Posted January 19, 2014 Mike, both carb sets are mounted to 220 intake manifolds. Maybe some one mounted them to what they could find at the time. Quote Link to comment
Sealik Posted January 19, 2014 Report Share Posted January 19, 2014 Hmm maybe that's a way to tell if off an L16 (220) and the L18 (K14) ??? Could be.....the K14 ports are a smidge under 1.5", whereas the 220 is 1.25 Quote Link to comment
Dantheman Posted January 19, 2014 Author Report Share Posted January 19, 2014 Both of my 220's are measuring at 1.5" Quote Link to comment
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