Which is the better carburetor? It had been said the Holley sat atop the high performance engines such as the L88, LT-1,etc. Then you have the quadrajet, which has been highly praised to the much maligned with knick names such as quadra bog/junk, etc. It has been proven that a properly tuned q-jet can perform just as well as a Holley. So will the advocates for both carbs state their opinions.

 

Nothing wrong with either one. I think the Q jet for a stock to mild performance driver prides better driveability. For higher HP and drag racing Ithink the Holley wins. The key is tuning. The Holley is easy to tune. The Q jet is tougher and there are not as many parts for it. A lot depends on what kind of driving you are doing.

 

I am sure there are people who can make the QJ a winner. I just have never had that experience. Swapped my QJ for a holley spreadbore and am completely satisfied. Good luck

 

I've had both and the Holley has less parts in the rebuild kit, is easier to take apart and put back together and there are plenty of places to get parts such as jets, power valves, etc.

You do need a pretty good depth of knowledge to get a Q-jet to perform at it's peak. They are more precise than Holleys which are great for drag racing but less so for cornering and twisties.

For everyday living and maintenance the Holley is the easiest one to live with IMHO.

cc

 

Agreed..
You'll not be working on a Qjet at the track like you can a Holley..
Qjets have way too many little pieces that are all important.

 

If you don't know Carbs like the back of your hand you would be better off with a Holly. Less parts parts are very easy to find

 

Okay, and now for the rest of the story. By the late 60's, Holley had established a well deserved reputation among hot rodders for building a great carb. Gas cost about $.10 a gallon and people were just beginning to notice that cars polluted.

GM developed the Quadrajet as a higher tech, more efficient devise. Over the years, as it was developed, it made all other production carbs obsolete.

GM used Holleys on the highest HP Corvette models, not because it would out perform the Quadrajet, but as a marketing tool. Holley was the name associated with "fast" at that time.

The Holley fuel metering system is simple. It meters a certain amount of fuel/ air, and dumps in some extra at WOT. Crude compared to a Quadrajet. But when gas was dirt cheap, it did not mater if half of your fuel was going out the tailpipe unburnt.

The Quadrajet uses a relatively complex system to accurately meter fuel to exact specs throughout the RPM range under various loads. Yes, you need to have a bit more knowledge to tune it, but it meters fuel very precisely and will still give as much performance at WOT as any other carburetor (or fuel injection for that mater).

Today, Holley is not the same company it was "back in the day". Their products suffer from poor quality control and customer service is lacking.

In the end, no other carb compares to the Quadrajet, it is the state of the carburetor art. Once you take the time to learn how they work (and it's not that hard), you will never want anything else.

God bless, Sensei

 

True what about the computer controlled holly's though?

 

Holley carbs are easier to work on and easier to rebuild for the average guy. A so-so mechanic can make a Holley run. It takes a very good mechanic to make a q-jet work. I say the q-jet is a better carb; but you have to find an expert to build it. If you don't have an expert to help, buy a Holley. I say throw them both away and convert to Fuel Injection-I did.

 

there is TBI to you know throttle body injection sorta like a carb

 

I vote Q-jet for long dependable trouble free service. I have a 12 year old rebuilt on my 79 Z-28 and except for carb cleaner every now and then I have not touched it. Passed emission testing several years in a row until they did away with testing here. I had one Holley in a mustang that ran really good one time for about a week. I have a Q-jet on my 454 that a1sensei rebuilt for me and the engines not in the car yet but it runs great on the stand so far. I gave up on the two holleys I had and tried first.

 

GM came out with the Q-jet in 66. The small front barrels were used
so that the carb would work well on everything from cars with 2 speed
powerglides in heavy impalas with no more then 3.08 rear gearing to pickup trucks. Even the holley on the 64 327/365 HP vettes did not have the 750 cfm size of the Q-jet. bigger holley vacuum carbs started showing up, the square bore carb is better for performance work GM did not use the Q-jet on any of the solid lifter high HP engines.

 

They can both be good and they can both be bad. I use both. The newer Holleys are trouble free. Bolt therm on, adjust the idle and you're usually good for a stock or near stock motor. The Street Avengers are superior carbs and offer super throttle response from off idle right through top end. I have two and love them both. For a good q-jet replacement carb use the Holley 4175 / 80550C - it is a bolt on replacement. Everything hooks right up and it works good right out the box. Small primary and large secondary similar to the q-jet - it is a very good choice for a factoy manifold. Fuel mileage will be less, but performance will not. The q-jet is a great all around carb if you know how to make it work. If you just want to bolt on go - the Holleys work great.

 

My Engine builder scofed when I told him I was going to run a q-jet on my 383...
Instead of getting it re-built I did get a holley...
He asked me when the last time I saw an amzing dyno run on youtube be headed witha quadrajet....
I said never....
but I agree taht they are prob more streetable. but holley's 4150 /60 desigh has been around for 30 plus years and has gained recognition as an excelent carb.

 

the q jet manufactured by rochester and carter are identical to gm specs and have twin part numbers..the q jet was developed to be the ultimate 4 barrel carb and it still is today......for street applications it is the best in the hands of a q jet expert. the holley is simply a knock off spread bore to retro fit for a q jet because of the many mis understod adjustments of the q jet.....holley was smart here because all the bad mouthing done back then and even now is false critizing the q jet....all out racing the q jet will do fine in the right hands, holley is much easier to tune for most folks and they work as well.....fuel injection and emission standards were the demise of the q jet mainly because it still relied on a choke plate and was prone to fuel perc. as with most carbs....the holleys are easier to tune and the spread bore base makes an adapter plate obsolete for a conversion.......

 

I told my machinist that a q-jet COULD be built for performance and perform as well as a holley if re-built by a person with the right knowledge of the q-jet...
He told me to send the holley to a person that is equally as vell versed in the world of holley and you'll have a Holley that can race and be a daily driver. It's a pointless argument but interesting never the less.
timg

 

I wish I hadn't gotten rid of my q-jet. While I was at tech school, I gave my q-jet to one of the instructors....... I should have known something was up when his face lit up as I was handing it to him. Didn't know better then.

 

yah i hope the engine i get has an Q-jet on it

 

I have one spare if needed....

 

oh is it completely redone on or one that needs resto and stuff