SU "tuna can" flat top carbs

[okayfine]

wasn't there a datsun roadster that was a 2.0? would this needle and jet fit these carbs?

There's the float bowl needle and seat, then the needle in the carb piston that fits into the jet. 2L Roadster stuff is the same as the Z, .10" needle bases, versus your .090" needle bases. Won't work.

Once you move away from engine sizes that Nissan ran, you're going to have to roll your own needles if you want every last bit of power without wasting fuel the rest of the time.

[okayfine]

so what year would these have been off of? I assume if they are sss carbs i'll just have to go to my original plan of rebuilding them from the nissan motor sports catalog with Z Su parts.

The didn't come on US 510s, so there's no year. Similar carbs came on US 1600 Roadsters, but not all the of the parts are the same.

Not many of the Z SU parts fit the 38s outside of the float bowl stuff, which you already have.

can they cross reference nissan part numbers to order my parts at Z therapy? i figure the exploded diagram of the carbs will help a lot. these carbs seem to be in pretty good shape, even the linkage is tight and unworn. probably mostly gaskets and other parts,and possibly throttle shafts. I am considering z therapys ball bearing throttle shafts.

You can make the gaskets yourself with some gasket paper, a template, and an X-acto knife. But it's not like they're expensive from ZTherapy.

Virtually everything but the linkage kit is NLA from Nissan. They're not in the business of supporting the old stuff like that, and only old-timer parts monkeys are even going to know what you're talking about when you start of the sentence with "SSS SUs, you know, like on the 510?"

ZTherapy will have no issues supplying whatever it is you may need.

With regards to the throttle shafts, it's not so much the shafts themselves that wear, it's the bushings in the OE carb bodies that wear.

[lostforawhile]

i'll try to find some pictures,but i machined some out of aircraft aluminum. I was shocked at the prices on some of the stuff i've seen online,so i made my own. , this should have been a quote on the lips that go in the air cleaners

[lostforawhile]

Ok i found a set of the same air cleaners with K&N filters, i have really close clearance, i had made a set of trick air cleaners, but they hit the heater core outlet on one side,and the brake booster on the other. how close these things clear everything amazes me, i was sure i was going to miss something. it even comes down to the drivers side fuel bowl almost hitting the master cyl, turns out for some reason my particular master has an odd blob of aluminum sticking out the side, which none of the others i've seen have. just an oddity on my particular car. as far as needles what would be the biggest needle and jet available for these carbs, this is a good size engine, and even with a mild cam going to take some good size needles to start a baseline

[lostforawhile]

Ok here's a picture, you can also see the spring plate,which replaces the springs on the heat shield,it's not needed in my application at all. and the back of the bar that pulls the choke cables together, they aren't hooked up at the second. normally they are round head cap screws that hold the pieces on the carbs, just used these bolts to hold them on in the picture. these are 240 z float tops,they have 1/8 npt aluminum inserts tig welded in, this gets rid of the banjo bolts and allows straight hook up to AN lines.
here's a short video of making the inlet pieces
http://video.google.com/videoplay?docid ... 9047958827

[lostforawhile]

Ok this is what i've got, this picture is from the guy restoring the 510 to factory condition,must say the most beautiful restoration i've ever seen. these are the carbs i've got, the carbs and manifold as a matter of fact. down to the number stamped on the manifold. i nearly fell out of my chair when i saw these.

[lostforawhile]

hey does anyone know what the threads are on the bowl vents for the datsun fuel bowl tops? are they 1/8 bsp like a lot of japanese makers like to use? if they are i already know where to get adaptors, just not sure what they were.

[okayfine]

i'll try to find some pictures,but i machined some out of aircraft aluminum. I was shocked at the prices on some of the stuff i've seen online,so i made my own. , this should have been a quote on the lips that go in the air cleaners

If'n the picture is what you machined, they aren't doing much more than bare carb mouths. You need a radius of at least 1/4" to do the job.

as far as needles what would be the biggest needle and jet available for these carbs, this is a good size engine, and even with a mild cam going to take some good size needles to start a baseline

For the 38s, it's the .090, like I've been telling you. These aren't Webers or anything, so you'll have to change how you view them in your mind.

Buy the DQ backissue I sent you information on earlier. It has all the details on modifying your needles. There's no buy-it-off-the-shelf option. 38s with airflow modifications and the correct needle will supply plenty of fuel for your engine. Where you may run in to trouble is if your Honda engine has a significantly higher redline than the L20B (for which I have baseline figures).

But then you're just juggling the tradeoffs of larger carbs versus your 38s.

[lostforawhile]

6500 redline,but you run out of torque before that, not sure with the delta cam yet, i'm going to order a grind for more low rpm torque vs torque at redline, i built this thing with long runners for torque not high rpm power, going to order the stuff you said, i'm taking the advice of everyone here, thats why i started the post. At least now i know what i've got. I'll memorize the section in the how to power tune SU carburators book, it's really good on custom profiling needles. just want to get a good base needle to start with,they aren't cheap. I still need to search for a good wideband gauge, watching ebay for a good used one. My exaust already has provisions for an O2 sensor, and i had already planned in the wiring for the gauge a long time ago. as far as the inlets on the carbs it's probably the angle of the picture but these have a pretty good angle on the chamfer, I looked at the factory steel ones on the Z aircleaner at the yard, and these have a much bigger radius then they had. if they don't work as planed i can always change the angle on them. Hey thanks everyone for the great advice on here, been browsing the forum,and there are some great cars here. I really like old school japanese sheet metal. always have. most of the guys on the other forum i belong to are the same way, we are one of the forums that hates fart cans and other obnoxious crap on japanese cars ,that seems to be so popular today. Oh has anyone had any vaccume problems with these types of carbs? talking about power brakes, I had already built a nice storage tank when i had planned to run webbers, made it from a 10 pound extinguisher, cleaned it out,painted it,made some nice aluminum brackets, and now it's bolted securly to the floor pan behind my seat.

[lostforawhile]

was wondering about the fuel bowls, they are supposed to sit level correct? I will probably have to make my own indexers for them,since my manifold isn't at a standard angle, but i was wondering if they were supposed to be at a certain angle.

[okayfine]

6500 redline,but you run out of torque before that,

You'll be fine with 38s.

I still need to search for a good wideband gauge

You don't want a gauge, you want datalogging and a laptop.

as far as the inlets on the carbs it's probably the angle of the picture but these have a pretty good angle on the chamfer

Radius. Angle of the chamfer doesn't matter, unless you have a hundred angles and end up with a radius.

and these have a much bigger radius then they had.

No, they don't.

Oh has anyone had any vaccume problems with these types of carbs? talking about power brakes,

Factory 510 SSS stuff in Japan ran brake boosters.

but i was wondering if they were supposed to be at a certain angle.

Flat/parallel with the ground. You can cant the SU bodies over to 20° if you like (common on Brit stuff), but the flow bowls want to sit flat. Less important on the Z float bowl lids than the loose SSS stuff, but always a good idea. different indexers are available. ZTherapy will be able to tell you if one is available to correct the angle you have, but you'll want to measure the angle beforehand so as not to waste their time.

[okayfine]

You want these:



http://www.aptfast.com

[lostforawhile]

i'll try to find some pictures,but i machined some out of aircraft aluminum. I was shocked at the prices on some of the stuff i've seen online,so i made my own. , this should have been a quote on the lips that go in the air cleaners

If'n the picture is what you machined, they aren't doing much more than bare carb mouths. You need a radius of at least 1/4" to do the job.

as far as needles what would be the biggest needle and jet available for these carbs, this is a good size engine, and even with a mild cam going to take some good size needles to start a baseline

For the 38s, it's the .090, like I've been telling you. These aren't Webers or anything, so you'll have to change how you view them in your mind.

Buy the DQ backissue I sent you information on earlier. It has all the details on modifying your needles. There's no buy-it-off-the-shelf option. 38s with airflow modifications and the correct needle will supply plenty of fuel for your engine. Where you may run in to trouble is if your Honda engine has a significantly higher redline than the L20B (for which I have baseline figures).

But then you're just juggling the tradeoffs of larger carbs versus your 38s.

do you think these ones i made will work once i add the radius on the lip? you are talking about where the sharp edge is where the air flows in correct? I haven't added a radius to the edge yet because i wasn't sure what one to add. pretty easy to do with a tool on the lathe.

[okayfine]

do you think these ones i made will work once i add the radius on the lip? you are talking about where the sharp edge is where the air flows in correct? I haven't added a radius to the edge yet because i wasn't sure what one to add. pretty easy to do with a tool on the lathe..

Radius the edge and it should be substantially similar to the parts I linked. 1/4" radius should be all you need. Beyond that it gets complicated and the results aren't as dramatic. If you have the ability to radius the edge, there's no need for the linked bits.

But if they're easy for you to produce and you can come to a design that works and is cheaper, you could sell a few sets. Dunno if you could sell enough sets at enough cost to make it worthwhile to you, but I know I'm in need of a set for my 46mm SUs.

[lostforawhile]

i'll post some pictures a little later,i just chucked the pieces in the lathe and cut the radius close using a tool I ground, then today i chucked them up and ran them at high speed in the lathe, at the same time they were turning, I used a die grinder with a one inch flap wheel to round out the radius. I cut too close to one of the dome vent holes and it split,so tomorrow i have to TIG it up and repair it with a dremel. overall it came out good, the holes to the top of the piston aren't critical i guess,just an air vent passage. I talked to someone at Z therapy and he recommended a needle that he says works very well on their two litre engines. it will jsut be a matter of seeing how it does. I will try to get a wideband gauge,i have no way to set up data logging software and a laptop in the car. so I have to do it the old fashiond way. I will use an infrared thermometer to keep checking each exaust runner to make sure no particular cyl is leaning out too much just going to take a lot of tuning. going to be a while anyway. still a lot of work to do with all the plumbing and wiring in the car. I did come up with a way to make air cleaners out of 1970s honda atv finned valve covers, more on that as the project gets under way, waiting for them from ebay. anyone know of a source for foam to make air cleaner elements out of? I know it used to be popular on V dubs I don't think i'll be able to make these intake pieces any cheaper then the link,they already have ton of work in them. aircraft aluminum round bar stock is not cheap eithier. had to use solid 3 inch stock as nothing standard has the corrct size center hole.