Captain Obvious

I believe those limiter bolts are just an attempt by Nissan to keep you from turning the knobs "too much". Kinda like the limiting caps on carburetor adjustments where they don't want you messing with them "too much". And in 72, they took that idea even further limiting the adjustment even more. Those are the funky large knobs on the underside of fhe 3-screw round tops.

Agreed! And I find it's the same way with people you've never met. For example... This is my mental picture of you:

Love it! That's a fantastic scene. Absolutely fantastic.

Thank you Mr X. Happy to hear you took the step to become part of the solution by removing yourself from the mutation pool. I want to stamp this thing out, and as long as there are enough hosts out there for this bug to propagate, we're at risk. So for all you people who cheer that fact that restrictions are being relaxed. Woo hoo! It's awesome, isn't it? All you people who like the fact that the numbers are going down. Yay! That's fantastic, right? Well if you like the results but have not gotten a vaccine yourself, you're setting us up for another round when this thing mutates and pokes through the vaccine. If you like the benefits, become part of the reason things are getting better. Don't rely on your friends and neighbors to fix the problem for you. Everybody's got an agenda, right? My agenda? I don't want to go through this ever again. I want life to go back to normal. I don't want to wear a mask. I miss seeing my Z friends and I guess I'm willing to go out on a limb a little bit for not just myself, but for other people as well. We're all in this together. So go get a vaccine! Get yourself out of the pool of mutation donors!

Smart man!

Bloats. Love it! So yeah, I'd be happy to have you test the bloats. It would add one more data point as to the validity of the modification. I'll send you PM!

Hahahaha!!! As a matter of fact, I've been informed (by the wireless carrier) that my old phone won't work for very much longer and they are sending me a new phone. And get this... The new one is a 4G flip phone!! LOL! I read the reviews for the new phone and they're terrible... Everyone says the screen is really small and the apps that you can put on it are crappy. Well duh. Sounds perfect. And speaking of my old phone... Now it's getting hot when I charge it and the back is a little bulgey. So I won't need any blankets to keep warm. The lithium fire will be plenty warm. Now I just need it to last long enough for the new replacement to get here.

Me too, but the on-road analysis might take a while until they end up on a car. You want me to send you the "heavy-duty" floats and you can try the whole thing out on your car? I'm actually comforted by the fact that someone thousands of miles away with different gas is having the same issues. Just another data point aiming at changes in the gasoline formulation.

I'm hoping!!!

Nice analysis. The geometry of the real system is definitely more complicated, but I think your simplified theoretical example is good enough for discussion here. As for the float shape, I think the conical tip may simply be to try to assure the float doesn't hit the inside of the bowl as the float tips beyond neutral. Despite that cone tip though, you can tip the 72 long ear floats so far up that you will hit the inside of the bowl. But the 72 long ears were an afterthought. So one might ask... "Why don't I just keep bending the tang down further to get the fuel level up?" My non-expert answer would be twofold: First, if you bend the tab down so far that the float contacts the underside of the lid, you're screwed. Second, even if you don't have to bend the tab down that far, you can end up on what I'm calling "the downhill slope" of the tab. By that, I mean... You have crested the top of the arc where the needle valve tip contacts the tab. And because of that, much of the force on the valve tip is actually to the side instead of straight up. It kinda pushes the valve tip to the side instead of up. Everything about the system indicates they wanted the floats to be close to neutral tilt. Doesn't have to be exact, but not to fat from neutral.

And just to make sure that my "in a glass" test method was valid, I tested again using the more traditional method with a piece of clear tube off the fuel nipple at the bottom of the bowls. Here's my rig: Here's the result for the rear bowl:: I did have a WTF moment with the front bowl... I put the fuel in, and it overflowed. I discovered that the float was stuck against the bottom of the bowl casting. Yet another fantastic feature of the long ear 72 design. So I emptied it and refilled while tapping on the bowl with a plastic screwdriver handle. That dislodged the float, and here's the result:

So I tried my ballasted floats today. Short story? They work great. I filed the high spots off the spackle. Not that I really needed to, but OCD does things like that: Then I set to trying them out... After a couple very simple, completely predictable tab bends, here's what I got. I set the level just a tiny bit low because 1) it will come up a little bit when there is a fuel pump pushing fuel, and 2) it will come up the width of the bowl gasket. Front looks like this: And here's the front tilt: And here's the rear after one completely predictable tang bend adjustment. Again, a little bit low on purpose: Here's the rear tilt: Based on the tilts, it looks like I could actually cut down on the weight a tiny bit. I'll make notes for if I ever have to do this again.

I'm hoping to be there. Will probably fly in and won't have my car though. @Dave WM How far up Pike's Peak did you get before you had to turn around?

Gotcha. And if you're running a closed loop system that uses lamdas, you should be able to control the mix good enough that you don't light the cat on fire. Good luck with the TIG. Run pure Argon. I wish I was better with mine, but I'm sure some of the faults are my own... I don't use a dedicated grinder for my electrodes (which is a no-no), and I don't have high-freq start, so I assume that my tips are contaminated before I really even get started. Sometimes it turns out good, and sometimes it doesn't. I'm no welder.

The only thing the shape of the float submerged matters much. I would theorize that you want the tapered nose because it would more gradually slope the pressure on the valve up and also not allow any trapped bubbles stuck under the float. But other than stuff like that, I can't see it mattering much. The problem is, as you mentioned, denser fuel will cause the float to sit higher. A higher float causes the valve to close sooner, and a valve that closes sooner results in a lower level in the bowl. And the issue is that I've had troubles getting the level high enough without the float actually hitting the underside of the lid. You remember this discussion you and I had almost ten years ago? I think this was all related to this same issue: https://www.classiczcars.com/forums/topic/43889-fuel-bowl-level-and-bending-tab-not-working/

Spackle is curing. We'll see how it all turns out! So in the meantime, I had a pair of old round tops here. History is I rebuilt these a number of years ago (in 2011... My how time flies) and ran them on my car for a little while before swapping them out for a pair of flat tops. The point is... I had the float levels on these in spec ten years ago and they've been sitting dry in a box since. In theory, they should still be in spec. Well guess what... Here's the front: and here's the rear: The floats have a neutral tilt when the valves close, but the level is way low. The bottom line is that the only thing that could have changed is the fuel. So I guess that brings up a new question... "OK, so it looks like fuel has changed over the last ten years. Is it going to be like that from here on moving forward, or is it going to switch back at some point in the future?"

duffman, Your results are about the same as mine. Able to bend the tab to get it "to work", but the tilt is uncomfortable and runs the risk of hitting the lid or inside of the bowl. Not to make it sound like I'm glad you've had problems too, but it's nice to not be the only one dealing with this. I should be able to spackle the ballasts over to day and give it a day for the epoxy to fully cure. I'll run final results then and let you know!

I did a little digging into the subject of gasoline changing over the years, and it's absolutely conceivable that there have been density changes as part of pollution reduction actions over the years. Not my area of expertise and I don't know what I'm looking at though, but here's a small snippet of the info out there: https://www.sunocoracefuels.com/tech-article/specific-gravity-matter https://www.epa.gov/fuels-registration-reporting-and-compliance-help/gasoline-properties-over-time https://nepis.epa.gov/Exe/ZyPDF.cgi?Dockey=P100B3YI.pdf https://nepis.epa.gov/Exe/ZyPDF.cgi?Dockey=P100T5J6.pdf

Agreed. From what I can gather from the various discussions about setting the float levels, I'm not the only one that has had difficult to explain results getting the levels correct. But i think most people just bend the tab and eventually get it close enough where it will work and they get tired of messing with it and call it a day. In fact, I have done that in the past. But this time I just couldn't get it close enough to even call it a day, so I started digging deeper for the root cause. It could be that the original floats are now on the knife edge of being able to be adjusted into spec due to changing fuel over the years. And I'm thinking that maybe these 72 carbs (which have slightly different float geometries than the previous years) are closer to that edge than other years? I'd be interested in having carb experts weigh in as well. I'm pretty sure they aren't ballasting the floats. I also wonder what would happen if I checked my float levels with gas purchased in some other part of the country far from where I am.

Are you in a part of the world that requires a cat? Or is there some other reason you feel the need to add one?

So today I decided to add some weight in a more permanent way... First of all... Anyone ever wonder what's inside the float? How is the mounting tab anchored? Well, it looks like this: So armed with the knowledge that the mounting tab does not extend very far down into the float... I drilled hole in the float: And made a brass slug to press into the hole: Rinsed and repeated for the other float and now I have these: In case anyone wonders... The little threaded hole is so I can run a small screw into the brass ballast slug as a removal handle. I figure that until I'm sure about the amount of weight, I might want to pull it back out. And since the hole is blind (I didn't drill all the way through), there's no way to grab it. Works like this: Here's the results in the front carb (long ear). Level is a little high, but that's easily fixable with a little tab bending: Long ear float tilt looks like this: And the rear (short ear results): With it's corresponding float tilt: Again, it's fantastic when the theory lines up with realty. The plan now is to spackle over the ballast plugs with JB Weld since it's fuel resistant and then do the final adjustments. I still have no answer to "Am I the only one that has this problem", but at least I have a solution.

Oh, and before anybody asks "Why did you pick 9 grams of extra weight?" The answer is "because that's what I found in my scraps box."

I messed around a little today with additional weight on the float. I wired a chunk of scrap steel to the bottom of one of my new aftermarket floats. The float weighs about 9-10 grams and I added about 9 grams of extra weight. For the test, I just wired it into place so it wouldn't fall off. Looked like this: I put that contraption on the 72 short ear lid. Float tab looked like this: Since this is the rear lid, it's still one mm low, but there's plenty of compliance in the tab bending to bring it up a mm: Here's the float tilt. Very close to neutral: And then I took the same float, with the same tab and put it into the front long ear lid. The result was this: With a darn near perfect tilt as well: So it's nice that the theory and geometry agree with reality. But still the big outstanding question is.... Why do I need to go through these lengths of adding weight to get the floats to behave properly??? Special extra-dense low volatility North-East summer blend gasoline?

So I also understand that this whole thing is like trying to "prove reality". What is reality, and how do you prove it? It's philosophy. For all you know, you are currently in a coma laying in a hospital right now and this is all a dream. You had a bad car accident six months ago and none of this is real. You might wake up tomorrow and find that all of this has been a dream. You really just can't prove it. So I guess I'm just trying to attach some kind of objective guide to a subjective life because that's all I got. If I don't know what to believe or who to trust, my conservative nature turns me to the long standing big names in media that have a long standing reputation and skin in the game. If a couple big names in media all say the same thing, then I give it credence. And if a situation gets beyond that, the courts decide. All the new on-line sources that have been around for just a couple years. With patriotic sounding names. Not going there. Either side leaning. So you might call me a sheeple, right? Following the old-school establishment? While others are being lured off to the side by someone whispering sweet nothings in their ear... "follow me... everyone else is fake." So I gotta ask... Who's the sheeple?

Here's another media bias chart, but I don't like it as much as the other one. Why? Because it makes no distinction as to the reliability of the source, just the political lean. The other chart above produces the bell curve by rating both reliability AND political leaning and I think it provides a much better "at-a-glance" view of the situation. I also don't like the fact that this chart it's a mish-mash mix of "opinion" and "news" sources. For example... Fox News Opinion (oxymoron) is listed as far right as you can go, while Fox News "news only" is still listed as right leaning, but not as much. That's fine and all makes sense to me. My issue is that they have CNN listed as "on-line news opinion only" (another oxymoron) and it's in the leftmost column. So is that CNN's opinion category, or CNN's news category? It's not split up like Fox is. Same with MSNBC. Other's make perfect sense, like Wall Street Journal". Their news section is in the middle, while their opinion section leans right. I get it. But they should provide the same treatment to all the media outlets and many of them they didn't separate the news and opinion. But anyway, here's another chart with all my (clearly my opinion) caveats: That one came from here >> https://www.allsides.com/blog/new-allsides-media-bias-chart-announcing-version-4