I would like to know what makes one carb better for performance than another? I want to know what makes Holley's so much better and leave out ANYTHING to do with ease of tuning because I can change jets and rods in an Edelbrock and a Q-Jet in less than 5 minutes? I want to know the reason everyone says Holley is what to use for performance where Edelbrock is what to use for street manners and economy on the street? I want to know what makes a Holley better than a properly tuned and heavily modified Q-Jet? What makes a Holley better than a properly tuned Edelbrock? In my eyes, a carb is a carb. Now the Q-Jet may be an exception because they were designed as emissions carbs, but once you go in and modify the idle circuit and properly tune one, what still makes a Holley better? I know ALL the performance models used a Holley, so don't say that. I want to know what design characteristics make it a better carb. If you don't know anything about how each carb works and are answering solely on experience, please withhold your answers. I am trying to get an answer that is based on the design and workings of the carb, ot so much with YOUR experiences. An answer based on experiences may be swayed by one not knowing HOW to properly tune or modify a Q-Jet, thus he/she would say they are junk. Thank you.

the Holley is better because all the high performance cars came with them- but the only reason they came with them was because the engineers knew that people were just going to put a Holley on it anyways, and i'm sure holley gave them a good deal when they bought thousands of carbs at a time.
Holleys are also better because every NASCAR race winner for the last 40+ years has had a Holey carb- never mind that they had to use a Holley becasue of the rules.
Holleys are better because they spend more money on marketing every year.
Holleys are better because they always give you an excuse to work on your car whenever the seasons change.
me, i'm a q-jet guy. i'm weird in that i like throttle response, power, and economy without all the tweaking, and i don't care that Rochester doesn't take out full page ads in magazines or if no one has ever won a NASCAR race with one.

Go with the Holley if you want to leak gas all over the intake manifold every time you change jets, or if you want to break the baseplate when bolting the carb down or have to invent special tools to adjust the fast idle. I don't mind rebuilding Holleys, I just don't want have to use one. Make mine Q-jet.

Holley is better hands down..chevy doesnt use qjets on hi-performance cars for a reason??..and an edelbrock is for beginners!!

I appreciate all your responses, but remember I want why and not because they came on all the performance cars or ANYTHING like that. I want to know what makes them "better". Is there something inside the venturies or something along those lines that make them "better". I like my Q-Jet, but everyone says Holley is the way to go for performance and I want to know why. I know and I agree that just because they take out full page ads doesn't mean a thing and also just because they came on all the performance cars also doesn't mean a thing. Q-Jets were made for emissions purposes and they are complex to tune. IMO, that is why they were never given their dues and why they were never used on performance vehicles. Another reason is because they came with very stingy idle fuel delivery, but once you go in and modify all that, what still makes a Holley "better" in the eyes of the racers? I don't think there is anything, but you do have to know what you're doing in order to get them to run properly. Is it because the Holley is cut and dry so they make them ALL that way?

I want to know what is inside of a Holley that makes them "better" than any other carb?

PLEASE KEEP YOUR ANSWERS TO KNOWING THE INNER CONSTRUCTION AND WORKINGS OF THE CARB AND NOT PERSONAL EXPERIENCES.

I am not going to buy a carb based on someone elses experiences because I can tune any carb you give me. I want the carb that is going to perform the best and if that is a Holley, then so be it, but the only way I am going to buy one is if you can prove to me something INSIDE the carb makes it better.

Holley is better hands down..chevy doesnt use qjets on hi-performance cars for a reason??..and an edelbrock is for beginners!!


Bill, you said Holley is better hands down. Why and don't say because Chevy never used a Q-Jet on any of their performance vehicles. No offense, but that is an answer that a 2nd grader would give in a book report and we all know you are extremely more intelligent than a 2nd grader. I want this thread to be about "WHY" the Holley may or MAY NOT be better.

Charlie, I think you know the answer. There really isn't any significant difference between carburators that makes one better than the rest.
They all work and if properly tuned they'll run well, if not they won't.

Blonde, brunette, redhead, what is better performance wise? I think it's mostly a matter of opinion. If you had different carbs of equal size each tuned for the same engine, I don't think there would be any substantial performance difference.

I'm with Derrik and Jon. Make mine a Q-jet.

Mark

You are asking something that there is no real answer because most folks are not subjective and go with what they know and have been taught or learned. To someone that has never been exposed to a Holley but has been using/tuning Q-jets for years and knows them well when they do try a Holley they will be resistant and find it complex with all it's circuits. The key to tuning a Holley is learning it's many circuits and how to identify when to tune each. From a performance standpoint that makes the Holley more tunable giving the skilled tuner a big edge. I'm not saying a Q-jet doesn't perform though and you'll see guys winning races with any number of different brands of carbs. The key is overall combination not a single component.

Back to Holley, you'll find they come in about any size and are broken down into many categories to meet consumer needs. The 4150 style carb goes back to 1952 when they provided the carb used on the '57 T-Bird. I've been partial to Holley carbs since the 70's and have found them to be able to get good performance and good streetability as well as some fuel economy depending on how you drive.

GM did a good job with the Rochester Q-jet, the spreadbore design gives good throttle response and fuel economy if you can keep your foot out of it. Q-jets are know for leaking from plugs in the fuel bowl causing hard starts, erratic idle and poor fuel economy. Re-builders often epoxy these plugs to resolve these issues. In real high performance applications the small fuel bowl can cause fuel starvation. A better fuel delivery system can often overcome this...

Again though for most of us it really comes down to what you have taken the time to know and understand...

Dennis, you say it comes down to exposure? Answer me this, why did GM use the Holley on their "performance" models instead of the Q-Jet then? If anyone would know how to tune a Q-Jet it would have been GM. I am not saying the Q-Jet can't perform because I love mine, but why did GM use the Holley on the Z/28, LS-6 Chevelle and the ZL-1 Camaro? If there is in fact no real difference, why would GM go outside their product line to spend money for a carb if they could have just made the Q-Jet work? This alone may indicate some benefit to running a Holley.

From my limited experience the Q-Jet is the hands down winner in fuel economy...
As far as performance, I don't know...

Dennis, you say it comes down to exposure? Answer me this, why did GM use the Holley on their "performance" models instead of the Q-Jet then? If anyone would know how to tune a Q-Jet it would have been GM. I am not saying the Q-Jet can't perform because I love mine, but why did GM use the Holley on the Z/28, LS-6 Chevelle and the ZL-1 Camaro? If there is in fact no real difference, why would GM go outside their product line to spend money for a carb if they could have just made the Q-Jet work? This alone may indicate some benefit to running a Holley.

Charlie - I'm saying the responses you get from others comes down to what they have been exposed to. As for why Chevrolet used Holleys on some performance engines I think it was more complicated than just Holley was a better carb. I'm much better versed in tuning a Holley and do see them as a performance upgrade, like I said earlier it's a complex item and if you understand it's complexities the tuning is very refined making it the racers choice. It's also perception though as hotrodders in the day were yanking stock manifolds and carbs and installing aftermarket manifolds and Holley carbs. In contrast there are 10 sec BBC cars out there running Q-jets so no matter what Chevrolet's reasoning there is no end all answer to which is better.

From Edelbrock/Holley sitting on hot BBC causing the fuel to boil out of your bowls - I like the holley design better. On a holley the fuel bowls "hang" above the intake manifold while on an edelbrock, they "sit" on to of the manifold. With the holley hang-over, you get a little gap which helps a lot when it comes to heat absorption from the intake manifold to the carb. With Edelbrock, you there is no gap so the heat absorption is greater. I have an Edelbrock and have been fighting fuel percolation for years now...yes, tried all the shields, gaskets, tricks, etc....it's a lost war. Getting a holley soon!

I asked myself this question when i had to choose a 4 barrel carb for my camaro and i went with Edelbrock thunder series. Why because i had always used Holleys in the past and wanted a change of pace. I think this question is like why choose PS3 over Xbox, it's just a matter of opinion. I think both Edelbrock and Holley are the same. But if there is a reall answer to this i sure would luv to know.

Lots of interesting views here. When I was drag racing my dad (who was a GM mechanic for 43 years) tuned the Q-jet for incredible performance, better than the Holleys I borrowed from friends to try. Fuel economy Q-jet all the way, and the sound of those open secondaries is breathtaking!

I run an AED custom built Holley I love.

Appearance-wise I think Edelbrock is king, IMO.

I want to know what makes a Holley better than a properly tuned and heavily modified Q-Jet?

Maybe it's because you don't have to "heavily modify" a Holley?

Interesting subject and posts, I'm a q-jet fan and have always had good luck with them, never a leak or hot start issues, maybe more complicated than the others but you can also fine tune them better with some practice.

Never had a car w/ an AFB/Edelbrock, but have had Holley equiped cars and my experience with them were not great, they were the ones that leaked, warped and had starting problems. Had a car with a nice running QJ and put on a 600 Holley thinking better MPG and driveabilty (used adapter on same manifold), and soon went back to QJ to get MPG and driveabilty back.

GM did use the QJ in perfomance apps, didn't the Buick stage 1, Pontiac GTO, HO, and RAM III & IV engines use them? I believe Ford even had the QJ on the Cobra 429 in the early 70's for a year or two, why not on the bowtie, I dunno if there could be a mixture distribution issue with a spreadbore (doubtful), but I think it's as much marketing - it's gotta Holley so it's gotta be fast.

Those are my long-winded thoughts anyway, I think nearly any well-tuned carb can do the job, it's all in what you like & works best for you

Dennis, you say it comes down to exposure? Answer me this, why did GM use the Holley on their "performance" models instead of the Q-Jet then? If anyone would know how to tune a Q-Jet it would have been GM. I am not saying the Q-Jet can't perform because I love mine, but why did GM use the Holley on the Z/28, LS-6 Chevelle and the ZL-1 Camaro? If there is in fact no real difference, why would GM go outside their product line to spend money for a carb if they could have just made the Q-Jet work? This alone may indicate some benefit to running a Holley.

i personally think that they used the Holley on the high performance models because they wanted to add to the performance aura of the car- an LS6 Chevelle or COPO Camaro wouldn't seem right with the same quadrajet that was on the lesser engines. by that time, almost all of the race car guys were running Holley carbs, so they probably would have just taken off the stock carb and put a Holley on it, anyways.
and i'm sure Holley gave them a hell of a deal on truckloads of carbs.

I like the blonde, redhead, and brunette thinking but I'm not going down that path as it always bites me afterward.

I've had all three types on different cars over the years.

Our 64 GTO convertible had the tri-power removed and a 4150 Holley on the 389. That car screamed all day long and gas was cheap then. In 30 minutes or less and with very minor tuning I could tame it down or make it power wild by changing the jets, metering rods, and power valve.

My 71 Firebird Formula 455 had a OEM Q-jet on it. When I rebuilt the motor into a 540+ci monster the Q-jet needed only very minor tuning and it worked fine on the street. After a dyno test I went to a Holley 4165 spread bore as out of the box stock it gave me 15rhp more than the Q-jet. Like 15rhp meant much given I was already nearing 590rhp.

When I bought my Camaro it had a 600cfm Edelbrock on it and ran just fine. I had no problems with it other than the electric choke stuck on occasion. With the new motor I'm going back to a 4150 Holley for a couple impractical reasons. 1. Personal preference. I've worked on Holley's for more than 25 years and know them pretty much inside out. 2. Performance. I don't really care about MPG and I want the power punch of manual secondaries.

I looked at the Summit version of the old Ford Holley and seriously considered it but at only $100.00 delta I could get a 4150 7510cfm so why go with something I didn't know. If I wanted better MPG, I'd put a 4165 on vs. the 4150 and try really hard to keep the secondaries closed. Kinda hard but I could try.

The Holley square flange style carb can be considered the better "performance" carb mainly because the square flange offers better distribution at higher rpms. Also, the overall fuel metering design seems to have a flatter fuel curve on the top end thus resulting in more HP potential. That being said, there are many mods that can be done to other style carbs to make them perform as well or maybe in some instances better than the Holley style so fans of other carbs don't beat me up on this answer! Given the choice if max power is desired I would go with the Holley style carb without question. Now you might argue that the Edelbrock(Carter design) is also a square flange, how come it doesn't measure up? It's downfall is it doesn't have the fuel handling capacity of a holley style carb, is only offered in smaller sizes, as well as its top end fuel curve is not as flat. For most street applications up to about 6000 rpm or so, any of the three can be tuned to run well and make similiar power. For more race applications and high rpm for the most part the holley style will have an edge.

Some Pros and Cons:

Q-Jet

Con,..small fuel bowl (for performance apps simply get a bigger needle and seat)
Pro,..secondary rod changes (where the power is) takes two minutes
Pro,..there are no secondary jets to replace or tune
Pro,..better fuel mileage
Pro,..requires very little pump pressure (but you'll always need volume for performance apps)
Con,..air horn could be warped from years of over-tightening the carb mounting bolts, causing internal vacuum leaks
Con,..complicated. But spend the time to understand the key systems and you'll appreciate the advanced engineering over a Holley. Any time you hear somebody say the term "quadra-dog" or "quadra-bog", you're talking to someone with a small understanding of Q-Jets
Con,..power piston can get stuck, especially if corrosion is evident
Pro,..sleeper carb that flows 750 cfm
Con,..the secondary air valve is a bit tricky to adjust but means everything to how the carb performs (again, learn about the q-jet)
Con,..requires a spead-bore intake (no big deal)
Con,..1975 and later q-jets don't seem to have the tuning "range"; idle mix for instance.
Pro,..one size fits all up to 450 HP, due to the "air-valve" design
Con,..new parts are somewhat available at best (here's a great place: http://www.carburetion.com/parts.htm )
Pro,..probably meters fuel better in ordinary driving conditions than a Holley due to it's smaller primary bores which would send a better vacuum signal
Con,..rebuilt carbs are often ruined.
Pro,..for the same reason, I think the Q-Jet handles larger cams at lower RPM levels than a Holley
Con,..but, you must have a weaker power-piston spring with a larger cam
Con,..finding good rebuildable cores are getting tougher and expensive
Con,..adjusting the float is a pain but once it's set, it's set.
Con,..threads for fuel line often stripped
Pro,..seems to need less tuning. Things stay put.

Holley

Pro,..dozens of brand new models available including much larger carbs than q-jets
Pro,..legendary.
Pro,..most all parts are readily available
Con,..too large a Holley will be miserable to drive. Too small will cost power (one size doesn't fit all)
Pro,..huge fuel bowls
Pro,..perhaps more intake manifold options
Con,..must have the correct vacuum secondary spring needed for your app or she won't do what your foot tells her to do.
Pro,.."chokeless" versions available (HP series, sweet carbs)
Pro,..float adjustments are a breeze
Pro,..the double-pumper carbs (mechanical secondaries) are as easy to tune as it gets
Con,..power valve selection isn't as easy it sounds. For me, it's more trial and error. But it's important to get the correct one for your app,..or she'll be rich at all times, or too lean when you "go loud".
Pro,..literally a 1000 ways to set up a 4150 Holley with various parts and components
Pro,..less sensitive to larger cams (a q-jet would need to be tuned with a matching power piston spring to the vacuum signal)
Con,..pitiful mileage (if you care,..I don't)

Edelbrock

N/A,..I've only worked on two and couldn't get either to do what I wanted so I can't say anything about Edelbrocks. How about one pro or con:

Con,..it's ugly

Perhaps others can add to the pros and cons of each of the three, or argue with my findings. It's what we do.

The best advice is to buy a book and learn about the carb. Good luck with whatever you choose.

Lastly, the well plugs on Q-Jets. This gets brought up a lot but I once did an experiment. I was trying to determine why my q-jets could 'run out of gas' after not driven for 4-5 days. I filled 6 old (I mean old) q-jet bodies with water to see if any would drip from the well plugs below, and none did after being left overnight. Of the six, only one had the epoxy fix said to prevent the leaks. I think this problem may be overstated. I've decided that today's gasoline evaporates at a much quicker rate than yesteryear's. FWIW.

Agree with Freezined above.

Q-Jets were indeed on top of many performance engines of the day. In addition to his list, how about the Q-Jet equipped 390-HP L-36 427 Corvette of 68-69. In addition to the 390 ponies, it had 460 ft/lbs of torque. Put a 750 VS Holley on top of that engine, compare on a dyno and I'd bet you wouldn't see a 1% difference either way; well within the testing error.

i think all the later Buick muscle cars had a quadrajet on them- and i don't think anyone here will claim that a GS with any "stage" motor in it was a slouch.
same with the later Pontiacs- i believe the quadrajet was the top dog carb for most of their cars after they got rid of the tri power setups.
Olds, too.
actually, it's starting to look like only Chevy used Holley carbs..

From Edelbrock/Holley sitting on hot BBC causing the fuel to boil out of your bowls - I like the holley design better. On a holley the fuel bowls "hang" above the intake manifold while on an edelbrock, they "sit" on to of the manifold. With the holley hang-over, you get a little gap which helps a lot when it comes to heat absorption from the intake manifold to the carb. With Edelbrock, you there is no gap so the heat absorption is greater. I have an Edelbrock and have been fighting fuel percolation for years now...yes, tried all the shields, gaskets, tricks, etc....it's a lost war. Getting a holley soon!

I have had 2 Edelbrocks and NEVER had fuel percolation. I ALWAYS use a phenolic spacer and NEVER had fuel percolation. NEVER had fuel leak out of the bowls while jetting. The Edelbrock is known for being the best at this because of its air horn being a piece that comes off well above the fuel level.

Interesting subject and posts, I'm a q-jet fan and have always had good luck with them, never a leak or hot start issues, maybe more complicated than the others but you can also fine tune them better with some practice.

Never had a car w/ an AFB/Edelbrock, but have had Holley equiped cars and my experience with them were not great, they were the ones that leaked, warped and had starting problems. Had a car with a nice running QJ and put on a 600 Holley thinking better MPG and driveabilty (used adapter on same manifold), and soon went back to QJ to get MPG and driveabilty back.

GM did use the QJ in perfomance apps, didn't the Buick stage 1, Pontiac GTO, HO, and RAM III & IV engines use them? I believe Ford even had the QJ on the Cobra 429 in the early 70's for a year or two, why not on the bowtie, I dunno if there could be a mixture distribution issue with a spreadbore (doubtful), but I think it's as much marketing - it's gotta Holley so it's gotta be fast.

Those are my long-winded thoughts anyway, I think nearly any well-tuned carb can do the job, it's all in what you like & works best for you

I think you have hit it on the nose. Over the many many years the performance market has been around, the name Holley has been forever linked with performance so if they said it had a Holley on it, that meant it had to be faster. You are correct. ALL the vehicles you listed had a Q-Jet on it and we all know how well the Cobra, Buick GS, GTO, Ram Air III & IV, and Stage 1 ran.

Great answers. Straight Line has listed some beautiful pros/cons, but I don't agree with one. The con about idle fuel tuning on the 75-later models. If you change the idle tubes, the down channel restrictions, enlarge the idle mixture screws, and enlarge the idle bypass air holes this gives you a very wide tuning ability. One great thing about the Q-Jet is its idle bypass air. This feature allows for the use of large cams without the need to drill the throttle plates or turn the idle speed screw in so far that you start running off the main circuit instead of the idle circuit.

Novaderrik, I never thought of it your way. It does seem that ONLY Chevy used the Holley. GREAT OBSERVATION!!!

This turned into a very good CIVIL debate on this subject. The biggest problems I ran across with the Quadrajets were the foam floats saturating, throttle shafts getting worn, and warpage from over-tightening after rebuilds. It has been years now since I have worked on them now but there was a guy that lived in Laramie, Wyoming in the 60's through the 80's (when I left that area) that would only work on Quadrajet and he could get them perfect each time. All of the Edlebrocks that I have dealt with have had stating problems. It seems as the longer they set the more cranking and pumping needed to start. When tuning them I have found that I might as well buy the set of rods, etc. right off. The Holley has always had a weak link until they came out with the back-fire proof power valve. I also don't really care for the 'gas bath' on the intake when changing jets. Thanks for posting this. I think it is mostly a matter of personal preference and what the owner has had the best experience with. If a person buys a Brand X and continually has problems to the point that they buy a Brand Y and Brand Y performs perfectly, the thought then becomes Brand X is junk and Brand Y is the best.

Holley is used on the fastest street cars on the planet.http://www.candsspecialties.com/

Also, who wants to raise the hood and look at an edelbrock or a QJET.

Actully, the fastest cars on the planet don't use carbs at all,..

Actully, the fastest cars on the planet don't use carbs at all,..

X2 and some would say the same thing about Holley's. I find my Q-Jet to be very attractive:) Sleeper.

I used to get a laugh out of guys that I had just beat when they looked at my engine and saw the q-jet on top of the engine. They just walked away shaking their head...... priceless. :D

I stand corrected. Some of the fastest cars in the world.

Actully, the fastest cars on the planet don't use carbs at all,..

They don't use pistons, either...

two words: fuel injection...