Carburetors Are WAY Smarter Than You Think! Tuning Guru Bill Pink Shows Us Why (Carb vs EFI)

Ever wondered what makes a racing carburetor different from a regular carburetor that comes out of the box? Guys like Bill Pink here make carburetors that are very, very specific. And we're going to find out what that actually means. And yes, Bill Pink is Ed Pink's son. Fuel injection tells the engine how much fuel you're going to give it. Yeah. And it tells everything. Well, I'm sorry. You're doing this deal. You're good. You're good. He's about to go off. Yeah. Fuel injection tells the engine how much fuel it's going to get. With a carburetor, it's listening to what the engine's asking for and then giving it. How does it know what it's asking for? It's all about the signal. When that intake valve is open, the piston is moving down and it's creating that manifold vacuum. That manifold vacuum is is reaching up to here and it's pulling that air past this. When the air comes past this, it's going to create that signal back to the metering block, back to the to the float bowl to pull that fuel in. It's listening to what's going on, which is why all these different devices are so important cuz it there's like different listening apparatuses and then the fuel delivery that goes with it. That is very interesting. I'd say that's a pretty good explanation of what we're looking for cuz I don't think the average guy really understands what's going on. Like you get the people that are like, "Oh, it's just like a toilet bowl dumping fuel into the engine." And it's like not so much more. You know, we could spend hours on this just on metering blocks and base plates, breaking up the different circuitry of the carburetor from the auto circuit, transition, intermediate circuit, the main jet, how it all works and correlates together. This is a carburetor that's widely used and out here on the dirt cars or out asphalt cars. It's the closest thing to a street carburetor. Like we talked about, the carburetors only know what's underneath them. They supply what air fuel ratio they need. If you don't have the booster exactly aligned in the board, the booster is actually the device that will measure the air flow going through it that pulls a fuel out of the center hole and through the booster. Now you air going through that center hole, creates a low pressure and pulls Yeah. fuel. Yeah. And then it all comes from the the fuel bowl, then the main jets and up the main well. And you can change the fuel hole size. So many tuning aspects of a booster. This one here, we got a little bit of a back cut put in the back side of that. Mhm. This way it creates a harder signal sooner where if you look at these, these have a tremendous amount of signal because of that crossbar. Now, this one is one that we've modified. So, you can see the difference between those two. And these I had machined at my dad's engine shop in Vanise, California. Now, if you look at the center of the booster where the crossbar is, there are some series that say that that bar has to stay intact. Well, we left it intact. Engineered a little bit. Just a little bit. And the the bottom of the stem has been CNCed and the sides have been CNCed to where it's been narrowed. So it's not the same finish as you can see. Yeah, it's a lot different. Then you go to the NASCAR where they got the Camping World Series or the Infinity Cup. We call it the Bush where they allow you to do pretty much whatever you want. So it's narrowed down to 300,000. We got a Vshape in the bottom of it to help pull air around it. Using CFD you can study the air flow and the high pressure areas in the venturi. This area has got a lot of lot of disturbance. So what happens is when the air crosses over you create a lot of tumbling air which really screws up air signal and air flow. This area over here is more of a high pressure area. The lamina air flow really wants to stick to the side of the wall and follow in it because the way the air comes in it's actually being pulled in. It's not being forced in. Then you start forcing air in over the high speed the idle air jet here. to the high speed, you can create different pressure inside the metering block. And with the vent tubes, that's another thing. The the height here will change what they call the bowl pressure. If you've got a tide level half width of sight glass and you've got 140 mph air speed going across here, it's going to pressurize the bowl. So, all of a sudden, you have more weight pushing down the jets, which will actually richen the engine up. restrictor plate racing. We'd run these all the way up to the top, run them flat, and have about 38 of clearance between the the top of the lid and the carburetor vent tube. So, it would desensitize a booster in the carburetor in out of the draft. You didn't all of a sudden be behind another car and it's loading up rich or part throttle and it's not running good. And then you get out in the draft and all of a sudden she wakes up. The olden days, you would throw things against the wall and see what sticks. Well, that was think that we're talking about earlier, the plate days. There was so much development on these carburetors because of that. When you had that retriever plate on there, the engine was so sensitive to every small change you could make, right? So, I remember this stuff being huge. Like I said, getting it exactly where it's supposed to be. What was the difference between an annular discharge uh booster and the regular one? The drop leg. Yeah. Um the angler was really good at drafting. The thing is when you use an annular discharge booster, my boss told me it's just all about the venic attractant. Of course, I looked like what do you venic attracted and English? Yeah, exactly. Mark says that's the air column when it goes through the venturi that it is its tightest point like an hourglass. Mhm. So when you could take that hourglass and you could shift it, move it, lengthen it and whenever you got one cfm more air Mhm. That would be about one horsepower. Whatever you can gain through that plate by changing that column. And how you change a column. Did you do it with throttle blades? Did you do it with large screws? Anything to disrupt it or to change it. Yeah. Would be a plus. That's why I love carburetors cuz it's like it's part aerodynamics, part you know, chemistry cuz you got to get the fuel through there and you got to get the fuel to begin to atomize so it can then vaporize. You can't burn liquid fuel. though is doing more than just delivering fuel. You have to begin to atomize that fuel, right? And a lot of people will tell me, well, the job of the main well is to atomize the fuel. I don't look at that way. I look at the main well, it's got you can run a one degree taper, you can run a twoderee taper, you can run a two and a half, three°ree taper. And this changes a lot of things. All those emulsion bleeds act as timers on how they actually will allow you to pull fuel in. Okay. What's an emulsion bleed? Emotion bleed. That's for a different That's for different video. We'll have to pull 202 or 2011. That's that's high-end stuff. Explain those two pieces over there or these the different pieces. These are the two here. They're angular discharge and they basically have inserts. And these inserts come in a 500 ID, a 550, and a 600. And you can put whatever holes design that you think would work. These are all very symmetrical. We have done it to where we do five on one side and do one way over here. Then we would take and clock the insert to balance out the air fuel ratio from cylinder cylinder bias. And here's the banjo that they sit in. They just get pressed in there and the fuel goes around and these goes all the way down inside. And these are the drop legs that will make more horsepower than these. Will flow more air. That is a stock booster. As you can see, there's no back cut in it. It's got a very small hole. And the problem is is being this booster has no back cut like this. This one was a lot easier for it to pull fuel out at a lower RPM. High RPM it doesn't matter. It's still drawing fuel out of it. But once you get to where So would this be like where the difference becomes between like a street car carburetor and a a wide open race car Exactly. carburetor. Yeah. This is a carburetor that's what booster that's used for a 750 down leg and a 4412 Holly. So we found out that you put a back cut in those things. Now you there's other things you can do with the calibration far as getting more air into the engine. This will create a stronger signal. So at a lower RPM, it picks fuel up quicker out of the bolt. H. Now, how does that relate to the throttle response? It is tremendous. So, I mean, if you look at the two of these on the top, may not be able to tell. One's got a smaller and one much larger. I mean, we've actually have these to where they're quite a bit bigger, 045. You can change that radius and you can change change the radius, you change the back cut, the ID diameter. There's just so many different avenues you can do. You wouldn't want to get too big on a large Venturi carver like this. So, I mean, this one has the back cut boosters in them. And the ID is opened up over a stock stock booster, but we didn't go as far as we could because the fact that the size of this carburetor, the Venture, is a 1.61. Yeah. And it's an inch and 3/4 bottom. But if you can take your camera, it's going to flow a lot of air. It's got thin butterfly shafts in it. Yeah. It looks very uh straight. There's no right there's not a lot of nonsense in there. Well, explain that because I think that's one of the big differences between like a we call a purpose-built racing carburetor versus we'll call it the out of the box carburetor because Holl's not stupid, right? They didn't they understand all these things, but some of these things are mass-produced pieces, right? Versus the Ferrari that's everything's fit. Yeah. Holl's one purpose is is to make a component that's affordable that people can bolt on their car and and go race it or run on the street. They've done a very good job of it, but it's assembly line work. I mean, we can take one of these new carbers apart and I yeah, I could pick it apart and say what's this isn't right, this isn't right, and this isn't right. But I want I want to give somebody something that came out of my learning of what I think a carburetor should be done. You know, a street carburetor like let's say that was a street carburetor. It's actually calibrated and and different than a race carburetor. Race carburetor, you want throttle response and wide open throttle. Got to have drivability at par little bit of par throttle and wide open throttle. This thing, no wide open. It's all set up for drivability. Yeah. Throttle. Yeah. Throttle. Idle. Come. Yeah. Coming off idle. That's a big big difference there. Yeah. So, we can get into it later. I mean, the mixture screw settings for a street carburetor are different than you'd have for a race carburetor. So in reality, it's the tolerance stack here is what the biggest difference is. It's not it's not the the thinking of it and the components. It's so much more that it's the tolerance stack. It's like blueprinting an engine. Exactly. But you know what is blueprinting engine? It's basically going off what what the tolerances were for the manufacturer for Chevrolet or Chrysler that we know that when he put those boosters in, they want to be dead center. They don't want to be off left or right or back in front this way. So the closer we get them, the better we are. If you take a out of the box 750, whatever a really common size of a Holly double pumper mechanical secondary is, and you have your 750, what is left on yours that is stock? Like what kind of proprietary or your own unique design goes into one of these things? Cuz I see I mean this is not that. I mean, that's got your name on it. I don't think Holly made that. No, these none of this actually is Holly. These are aftermarket throttle shafts. Throttle blades are aftermarket. The fuel bowls are aftermarket. They're made by Dave Brazwell. Now, this is like the brains, right, of the carburetor. It's a It's a big part of it. Yeah, it's a big part of it. So, explain what's in a metering block in the 101. How does a metering block work? Well, we got them right here. There you go. You got them. Hey, just happen to have some fresh from them. Here's a brand new metering plate. And it's real simple. I mean this is the we can so this is a tide area where all the fuel is maintained and it will stay at a certain level via the float and that's your fuel reservoir back here on that side right here are the main jets those are interchangeable. Mhm. And you could change them whenever you want whenever you think your horsepower needs it or air's air's gotten better. One thing about that with a carburetor when the air does get better these boosters know it and they will sense the air density and change the calibration. It's very simple, you know, in the fact that it's got a job of basically calibrating the fuel. One way to think about before we go too far, when we do one of these carburetors, we want the the fuel curve to follow the torque curve, right? So, when the fuel follows the torque curve, the the horsepower curve comes up too. Yeah. Because basically, I mean, you look at peak torque and that is what they call me vomit efficiency. Yep. It's where the engine is balanced far boring stroke, rod to stroke ratio, bow event timing, compression rate, everything's happy. It's make it's wonderful. So, the better you can make that fuel curve at peak torque follow it, the the better off you are. So, I got the jets on the backside here, right? And they're feeding in to these holes. No, where where's where does the jet what's going on in here? I'm like, follow the fuel. The main jet fuel goes in here. This is the main side. So this is on actually, how would you want to call that, Blake? Do you call it the reservoir side or you want side? I call it the fuel bowl side. Yep. And what it does is pretty much is everything runs off the main jet. Now that's everything has to go meter through the main well and is this thing is sitting there idling. There is going to be fuel being pulled through this main well. And these all these passages are adjustable. Right now there's nothing in them. But as you work to the top and work your way down, these passages get a lot weaker. So this is a very sensitive passage passage up here. And this is where we tune the bottom end of the engine. As we get more towards the the top end numbers, we start feeding in here because the air speeds up higher and it's pulling more fuel out. So the fuel is going in at the bottom. It is going up this well and then entering back through this passage. This is all air this side. There's no no fuel on this side at all. This is an air passage. Okay. So, is that's connected to where Okay. Yeah. I'm I'm Don't Don't get lost because we haven't gotten to where you you're asking yet. So, that's all controlled by the highspeed. Okay. And the thing is everybody says a high speed, man, that that leans out the top end. Not true. What the high-speed does is it controls how much throttle blade opening you have before it starts pulling booster fuel out the boosters. Now, if you start putting more high-speed in, they say, "Well, it takes fuel away from the top end." It does because it's allowing this pass P package right here to work better. Okay. So, I think I'm putting this together now. This is air right here. And does this this leads into here's the fuel side? Correct. This does. So, this is coming in through like that. Yeah. It comes in through here. So, when that hole here is lined up with here, right here. Mhm. That's what this these are air timers. That's all that is. Okay? You know, that is where the fuel comes out of the main well. And if you had no holes here, that fuel will just flow right up through there. You'd have it'd be just too rich. It wouldn't even run. So, this is why you put these holes in here because they will actually slow the air signal, the fuel signal down when the engine's just getting off throttle. How soon do you want fuel coming out the boosters? Well, if let's say you got a two barrel and it's got a big hole with a stock booster like this, well, you're going to need fuel right away, but it's got a big hole in a big signal. So, you wouldn't get very aggressive here on the top holes. But now, if we were to take and put this booster in with a back cut and a bigger cross dimensional hole here, well, you know, you can get a little bit more aggressive here because it's going to have a stronger signal to pull fuel out the stem. So this this air channel here is coming through these or one of these. That's where the air is coming from. That's the only place that air will actually enter from here. So this just there's no vacuum coming through here. This is just air flow flowing over this that's kind of manipulating what's going on in there. It's all vacuum. So where's the air? Is there something air coming out of the bottom of here? Might as well ask. It's vacuum and it's coming from the engine. Okay. Yeah, that that's what I'm trying to clear out. It's going up and down the valves and open and stuff like that is pulling constantly. Yeah. So, where's the air coming in and going out? It's coming in here, right? Yeah. So, when this is Do you have a body that's not bolted something? So, we can see like what the back side of this looks like without giving any way any secrets. Fuel injection tells the carburetor or tells the engine how much fuel you're going to give it. Yeah. And it tells everything. And well, I'm sorry. You're doing You're good. You're good. He's about to go off. Yeah. You know, so like Harvard would say, you know, fuel injection tells the engine how much fuel it's going to get, whereas with a carburetor, it's listening to what the engine's asking for and then giving it. Well, how does it know what it's asking for? It's all about the signal. So, when that intake valve is open and the piston is moving down and it's creating that manifold vacuum, that manifold vacuum is that is reaching up to here and it's pulling that air past this. When the air comes past this, it's going to create that signal like Bill said back to the metering block, back to the to the float bowl to pull that fuel in. So, it's listening to what's going on, which is why all these different devices are so important because it there's like different listening apparatuses and then the fuel delivery that goes with it. Whether it's a plate engine that's running a really narrow RPM range or a drag car that's running, you know, I guess a big difference would be a stick shift car versus an automatic, right? There's not as many shift points. So, the how broad that RPM band is makes a huge difference in all these things, right? That is very interesting. thing. I'd say that's a pretty good explanation of what we're looking for cuz I don't think the average guy really understands what's going on. Like you get the people that are like, "Oh, it's just like a toilet bowl dumping fuel into the engine and it's like not so much more." You know, we could spend hours on this just on metering blocks and base plates and and breaking up the different circuitry of the carburetor from the idle circuit transition on the intermediate circuit, the main jet, how it all works and correlates together. This this is the nitty-gritty that we're trying to figure out here because I don't know how this happens. I know fuel goes in, engine burns it, it's either happy or it's not, right? But following the pathway of where does okay fuel enter, exit, air, how does it correlate? Where's the interaction? Now, just FYI, a lot of this I don't want to educate too many people on like, you know what I mean? Am I asking questions you don't want to answer? You're doing a good job. Yeah. Okay, you go ahead and…