Just like all the others that were here when I became a member and have left.

Its good that the OP is enjoying his car. It is unusual his old Qjet bogged, as Qjets are not supposed to bog when set up correctly. Mine doesn't, it responds crisply when I blip the throttle. By their design, Qjets are highly responsive to low airflow conditions which makes up the majority of street driving. This is where Holleys are at their worst as they have far less sensitivity with low airflow and use large dual accel pumps as a band aid. Accel pumps compensate for a carb's inability to respond to quick changes in airflow, bigger the accel pump the poorer the carb can respond to airflow changes. Therefore, a carb with a smaller accel pump is a better street carb than one with big accel pumps to cover up its flaws for street use. Holley double pumpers, which are good race track carbs, are very poor at sensing engine requirements and require two large accel pumps to hide their poor airflow response.

Another way to think of it is that a Qjet and most oem carbs supplies fuel as the engine requires it, while a double pumper forces fuel down the engine if it needs it or not. Which is not great for MPGs or engine life. But both carbs can be made to work, which the OP seems to have done.

I'd bet money my 950 HP flows better than any thing anyone thats posted in this thread had.
But then, my 406 will be putting out around 550hp as a daily driver. It must be a race car.

Everything in bold is incorrect. I really wish people wouldn't post things they have no clue about. I'm sure you're intentions are good but posting misinformation is not helpful at all.

The ONLY difference in a mechanical carb (DP) and vacuum carb is how the opening of the secondaries are controlled. Fuel metering is handled in the same manner. Now, different boosters do generate different fuel "curves" and atomize the fuel better but that works the same for both type carbs. I can promise you a mechanical secondary carb with annular discharge boosters when tuned properly on a health engine will give near fuel injection response right off idle.

The size and number of accelerator pumps isn't any indications of efficiency or how much fuel is "dumped" - it's all about the "tune" with the pump cams and squirters on the Holleys. There's no more chance of washing down the engine and killing engine life with a mechanical secondary carb as it is with a vacuum carb if it's set up properly. All the horror stories generated around mechanical secondary carbs stem solely from folks that probably had no business working on the car to begin with.

Rochester, Holley, Carter, etc Carbs

What is the difference between Rochester, Carter, Holley, and Edelbrock, Barry Grant, et alii.

The first three brands have been available on factory production cars. Edelbrock and Barry Grant, among others, are aftermarket only, but are based on, and thus functionally similar to certain carbs from Rochester, Carter, and Holley.

Holley carbs were found on some production cars through the ages, but certainly not to the extent of the proliferation of Rochester or Carter carbs. please let us not forget the eminently forgettable Holley/Weber progressive (yes, progressive, as in one primary and one secondary) 2bbl carb found on such notable cars as the Vega, Pinto, and a slew of offshore 4 bangers... There were a whole bunch of these "OEM Holley" carbs produced. In truth, Holley carbs became much more popular after they became available only as aftermarket carburetors.

In point of fact, the real rival to Rochester over the years was really Carter. The Thermoquad was Carter's answer to the Q-jet. It is also a spreadbore and has the added advantage (or disadvantage) of having a phenolic fuel bowl. This was intended to prevent heat transfer to the fuel with the higher underhood temps of emissions-controlled engines, but the plastic had a tendency to warp and split.

Sadly, Carters are quite obscure nowadays due to the proliferation of Q-Jets and Hollies. They are still available, but fetch a premium, as do new Hollies or Edelbrock carbs.

Edelbrock has two basic carb models, one based on the Carter AFB (square bore) [right guys???], and the other based on a Carter spreadbore that was much more similar to the Q-jet. The difference between these late-model Carters and Quadrajets was that the Carter had two Power Pistons, one for each primary venturii. This made the Carter eminently tunable: imagine boring only cylinders 1,3,5, and 7 0.030" over (one bank of cyls with bigger displacement), and leaving the other 4 alone, but still being able to tune the carb perfectly for both banks!

Barry Grant carbs are based on the typical Holley squarebore design, but are much more tuneable than Holleys are (and you pay for the advantage!). This because you can change the size of the venturiis by adding or removing sleeves to/from the venturii.

There are other carb brands available, one of which is Predator. The Predator (and the Kendig before it) use 2D venturies - basically a square passageway which narrows in one dimension only. Obviously this makes the variation in the venturi much easier to implement, as you only need to move a linear surface, not a circular one.

Which One????

This is a subjective question. The Holley guys will scream Holley. The Q-jets will cringe and support their local carb.

Whichever route you go, be prepared to expend time and energy learning how it works. There is nothing worse than tweaking a mechanism about which little is known.

My Holley doesn't bog. It can be susceptible to bogging if either the accelerator pump linkage has too much play or if too light a spring is installed in the secondary diaphragm housing (in the case of vacuum secondary carbs).

I don't know for sure what it was "designed" for, but I do know the still very popular 4150 series was introduced in 1957 for production vehicles, and that it and the 4160 model were used on production vehicles for some time after that. Also, I have had my Holley on my car in anything but WOT conditions. Take start-and-stop Washington D.C. traffic, for instance. Gotta love the downtown area around 15th and Constitution when the tourists are in full force! I even have good idle with it.

Now, one thing about Holley that separates it from Q-Jet is that Holley is a company that makes many different carburetors. The Q-jet is, itself, a carburetor. So, to blanketly say a Holley is optimized for WOT would be much more accurate if you're referencing the huge Dominator. However, that would not necessarily be true of a 390 cfm or 450 cfm Holley 4160 with vacuum secondaries. These would provide good economy and part throttle driveability even on small V8's. With enough tuning, I've gotten my 600 cfm squarebore to be acceptably efficient.

For a pure drag car, I dunno. I don't know from experience, but I've read some accounts that claim the Q-jet can be made to provide stellar performance even in drag racing. See, I can say nice things about Q-Jets, too :-)

I will sorta agree, that for any car that sees street driving in real traffic, the added sophisitcation of the Q-jet is unmatched. I will say that even though I've gotten acceptable efficiency from my Holley, it is not as forgiving of lead-footedness as the Q-Jet. However, here again, the carb under consideration is but one model: the 4160, part 1850-3. Another Holley, say a 4175 spreadbore with vac secondaries, (which has primaries almost as small as a Q-Jet) may provide much better economy. Some of the later Holleys even allow full electronic hookup to a car's ECM to maintain OEM emissions requirements.

It is true that Holley carbs are "high performance", in the sense that they are very good for drag racing, and they are almost always the carb of choice on dedicated drag-race cars. At wide open throttle, Holley's work very well, and this is what they are designed to do best. They are also modular, which makes them easy to rebuild, and relatively inexpensive.

However, if you drive your car on the street most of the time, you probably drive at full throttle for no more than a few seconds per day, if that. Under these conditions, there is relatively little airflow through the carburetor; for a carburetor to work well on the street, it has to have sensitive boosters that respond to small amounts of airflow. This is where the Holley carbs are at their worst. They have the least sensitive booster venturis of any carburetor I know of, which makes them poor low-speed performers; the usual result is poor gas mileage and increased exhaust pollutants. In the US where gas is relatively cheap this may be liveable with, in other countries where gas costs as much as US $5 per gallon, a Holley is probably not a great choice for a mainly street-driven car.

Both Carter carburetors and Quadrajets are designed from the start to be very responsive to part-throttle, low-airflow conditions. They use double or triple booster venturis, vacuum-responsive metering rods, and air-valve secondaries, all of which make the carb adapt better to the engine under the varied loads and speeds of street driving. Carter carbs are elegantly simple designs and easy to understand, Quadrajets are quite complex and it takes a little more effort and knowledge to tune one of them correctly, but once you get it done you will get better gas mileage, less exhaust pollution, better part throttle response, and just as good full-throttle performance. In my opinion, for a mainly street-driven car a Carter or Qjet is considerably better suited than a Holley. Between the Carter and Qjet it comes down to personal choice - each has advantages, especially if price is a factor and the Qjet is already on your car! The Qjet is a spreadbore carb (small primaries, big secondaries) which helps it perform well at both part-throttle and full-throttle.

For my money the best street carb of all is one that is no longer available - - the last and best Carter design, the ThermoQuad, which replaced the Carter AVS, which in turn replaced the Carter AFB that Edelbrock and Carter still make to this day. Like the Qjet, the ThermoQuad was a spreadbore design, and unlike the Qjet, it is a very simple and yet very effective design.

Unfortunately, mainly because of nostalgia and the association with 60's muscle cars, people buy older, less efficient carburetor designs in preference to newer ones. Holley found that out with their new-design 4010 and 4011 carbs which no one would buy in enough quantity to be profitable, and the only Carter that attained cult status is the ancient AFB design that Carter had already improved upon even before the muscle car era ended - it was already obsolete in the 1960's!

Some cynic once said something like "a carburetor is an incredibly ingenious and complex device designed to provide exactly the wrong air/fuel ratio under all conditions of load and speed". That's definitely not true, but sadly there's an element of truth in it, which is why every new car uses EFI.

Here's a little idea of mine to think about. A carburetor is supposed to sense airflow and meter fuel in response, which is how it "adjusts" to varying loads and engine rpms. An ideal carburetor would be so sensitive to air-velocity that it not need an accelerator pump at all (all the accelerator pump does is compensate for the carbs inability to respond to quick changes in airflow). It turns out there is at least one type of carburetor that *is* so responsive to air-flow that it does not, in fact, need an accel. pump - that is the Weber carb and its derivatives (Japanese copies , etc).

Carrying this line of reasoning a little further, a carb that gets by with a smaller accelerator pump (a smaller squirt of gasoline is adequate to cover up the carbs deficiencies) is a better street carb than one that requires a bigger accel. pump shot to cover up its flaws, i.e is more responsive to airflow and more likely to give you good mileage and good throttle response. A little investigation shows that ThermoQuads, Qjets, AFB's, AVS's, etc, all have smaller accel pump volume than Holleys. Worst of all are double-pumper, mechanical secondary Holleys, which, while great race carbs, don't really do a very good job of sensing the engines requirements at all - they need not one but two massive accelerator pumps to cover up their poor response to airflow.

While I don't doubt that someone who know what they are doing can make any of the above carbs work on their car, I think it is clear that by design the ThermoQuad, Qjet, AVS, etc, are better suited to an engine that works over a wide range of rpm and loading, i.e., any engine that runs mainly on the street.

Of course other factors such as availability, cost, and reliability go into any carb decision too. But if someone laid all these carbs out in front of me, all brand new, shiny, and functioning correctly, and asked me to pick one for my daily-driver car, the Holley - any Holley - is the last one I would pick. I would pick the ThermoQuad first, the Qjet next, the AVS after that, then the AFB, then vacuum secondary Holley's, and finally mechanical secondary Holley's.

Anyone preparing to vent their displeasure with my choices, remember, this is just my opinion! There's room in the world for a lot of different ones!

I've tried the Q-jet and Holley Double Pumper on my 71's 455. I'm happier with the 750 vacuum operated secondaries. I've slightly modified mine, but it works like a CHAMP. Either should do fine, as long as it's set up correctly for the application.

I know. You and a few others have quick, if not downright fast, cars. I'm just tired of these "stock only" guys bringing everything down.,,,,,, Seems most of these people think you can't have anything that doesn't say Edelbrock on your car and still drive it every day.

Maybe some time this year I'll get to update my build post. Cars been sitting in our storage lot for 2 years now.

BadSS, I do not post info I believe is bad or false. Here is a page about the various different types of carbs that are commonly used in V8 hotrodding. This is where I got the info you disagree with. http://www.442.com/oldsfaq/ofcrb.htm

Tooslow, 550 hp is pretty radical power level for a street car, even by modern sports car standards, and is especially high for the outdated frame and body structure in G bodies which start to break down at around 400 hp, even in pristine rust free shape yet alone the common rust bucket. Seen ripped rear lca mounts, blown out rear windshields from body twist, etc well below 500 hp. Just 110 hp from my old V6 caused cracks in the middle pillars on my Regal, these cars are as strong and rigid as a wet noodle and require a good amount of reinforcing.

Also I am tired of hearing about misinformation about how Qjets are junk, CCC is junk, and other BS. The Qjet CCC system can easily support 400 HP, and mine drives likes its EFI. At idle, I can put it in reverse and it back up over hills with no throttle applied at 600 rpm, and the engine accelerates smoothly with no lag when I press the pedal.

Most of the Gbody Buicks, even GNs either had 4 to 6 lower body bushings not installed, my n/a Regal Limited had 4 missing lower body bushings, but I installed those 4 lower bushings which did improve the handling.

As far as the info you posted on larger vs small accel pumps - He states: “a carb that gets by with a smaller accelerator pump (a smaller squirt of gasoline is adequate to cover up the carbs deficiencies) is a better street carb than one that requires a bigger accel. pump shot to cover up its flaws, i.e is more responsive to airflow and more likely to give you good mileage and good throttle response.”

OK, so you posted information in the first person when it's actually information you read somewhere on the internet and you have NO personal experience to know whether or not it is BS or not. Good job man - by the way, that's not helpful either.

I wasn’t going to read the link or even the cut and paste from the link, but while on the throne, I did read the insert and did a search for “forced” and “forces” and didn’t find anything there to indicate the author thinks a DP forces fuel into the engine whether needed or not. So, I’m assuming you came to your own and wrong conclusion about that.

His statement is accurate. You leaving out the info in the parenthesis and the word “shot” in “pump shot” makes what you posted inaccurate. If you need a smaller pump SHOT in one carb than the other, then yes the carb requiring a lesser pump SHOT (squirt of gas) is more efficiently metering the fuel in low vacuum situations. This is the case with the annular discharge boosters available in some Holleys – they require a lesser pump SHOT when compared to the more common down-leg booster carbs of the same CFM. However, usually when you need a lot of fuel from the pump SHOT it’s because the cam chosen is too big for the intended application (mainly the stall speed of the converter), or said another way, the stall speed on the converter is too low for the cam.

It appears by your post, you believe what the author wrote. The reason the 4010 and 4011 failed was because they did not respond well to tuning much if any from the stock setting/configuration. I’m using first person here because I know from firsthand experience. The only Holley carb I’ve never been able to get running right on the street in well over 100 cases,, including a few Dominators,,,, was a 4010. If you or the author had tuned on a 4010 or 4011 you wouldn’t think it’s a superior design. Newer, sure,,, more efficient, maybe,,,,, superior, no. I’m going to fall short of calling it a crap carb because it worked fairly well if it didn’t need much tuning, but it was NOT a “performance carb” and fell WAY short of the older design in regards to performance and tune-ability and that’s what people expect from a Holley - not having to break out the drill bits if you needed more "squirt" - which is typically needed when running a healthy cam. We quite selling them in my old speed shop because EVERY person that bought one wanted to return it. I’m sure we weren’t the only shop that quit selling them for the same reason.

Man, I really don’t like ragging on people and I’m not doing it to embarrass you or trying to convince you to think any other way than you do. If I didn’t care about the board or the folks that come here, I’d just let it go. However, I consider this the best resource for the SS community and felt like if I know something is wrong, it should be made known.