Holley vs. Q-Jet
Thread Starter
Burning Brakes
Joined: Aug 2001
Posts: 1,160
Likes: 3
From: Greensboro NC
Holley vs. Q-Jet
I never I thought I'd say this but I miss my Q-Jet. I just installed the setup below and found that Holley carbs are real nice and smooth but flat. I miss those nice big mechanical secondaries kicking in at exactly the same time no matter what. Almost as good as nos. :) So next week I will be selling the Holley and getting a new edelbrock Q-jet. Someone please talk me out of it!!! Tell me my Holley just needs something I dont know how to do!!!
Le Mans Master
Joined: Jan 2000
Posts: 8,721
Likes: 108
From: Canada
Re: Holley vs. Q-Jet (micks69)
Which Holley do you have and is it a vac or mech sec. Mechanical will give you that kick that vac. won't. My mechanic hates Holley's and thinks that the Edelbrock are the best things since well you know. I have only had holley's on my vette engines, LT-1 had a 650 dp, mech and my present 383 stroker has a 750 dp mech. It took a little playing around with the primary jet to get the best performance out of the 750. I would love to try the Speed Demon if anyone just happened to be in the Santa mood to lend one to me. The Holley's are more finicky? than the q-jets, as they need to be setup for summer driving then adjusted for the cooler weather in the fall.
Race Director
Joined: Dec 1999
Posts: 19,610
Likes: 778
From: Forked River NJ
Re: Holley vs. Q-Jet (page62)
You will have to change manifolds or get an adapter. The Holley just needs to be tuned better. I think the Q Jet is a little more flexible tha nthe Holley but the Holley should be able to run strong. They need some tuning. Most people either love them or hate them. Mine is working great right now and it needs some tuning.
Safety Car
Joined: Aug 2000
Posts: 3,711
Likes: 43
From: San Antonio TX
Re: Holley vs. Q-Jet (micks69)
You need to do some basic tuning on the Holley, particularly in the secondary opening rate. I had to go to the lightest white spring in my Holley spreadbore to get the right response. To tell the truth, the Holley doesn't perform any better or any worse than a Q-Jet. Unless you like spending the money, it would be far cheaper to do some simple tuning. In about 10 minutes, you'll have the carburetor you want.
Melting Slicks
Joined: Apr 2000
Posts: 3,286
Likes: 8
From: San Jose California
Re: Holley vs. Q-Jet (micks69)
Your Holley with the center pivot bowls will be a much better carb if you like to take corners fast. As for straight line, the Holley should be good for a few hp more than the QJet. If not, you still don't have it setup right. Did you bolt it on right out of the box? Did you order the one for your actual application, or is it a generic model setup for who knows what?
If the secondaries open too fast the carb will bog. If they are not opening fast enough, change to a lighter spring as has been suggested. There are quite a few to choose from. The right one is available, you just have to figure out which one it is. Are you sure that the throttle is in fact opening all the way. Many have been burned by this this last year including me.
Jets will make some difference, but not as much as many people think. It was probably pretty close as delivered. Get the throttle, secondary springs set up first, then tweak with the jets, if needed.
Chuck
If the secondaries open too fast the carb will bog. If they are not opening fast enough, change to a lighter spring as has been suggested. There are quite a few to choose from. The right one is available, you just have to figure out which one it is. Are you sure that the throttle is in fact opening all the way. Many have been burned by this this last year including me.
Jets will make some difference, but not as much as many people think. It was probably pretty close as delivered. Get the throttle, secondary springs set up first, then tweak with the jets, if needed.
Chuck
Thread Starter
Burning Brakes
Joined: Aug 2001
Posts: 1,160
Likes: 3
From: Greensboro NC
Re: Holley vs. Q-Jet (Chuck Harmon)
Ok, I was really trying to nice when I said the Holley was a good carb.
I don't like it all!!!
I've put the yellow spring in and didnt make any difference (there is only 1 step lighter, white). Also it doesnt idle well at all. In fact the idle goes up and down beetween 1100 and 700 rpm's and no I don't have any vac leaks. It doesn't start well when warm. The choke is worthless (electric and yes I do have power to it) The carb's only redeeming factor is it looks very nice.
I understand that to achieve maximum or optimum performance a new product may require some adjustment. But the thing should run fairly well out of the box. This one runs kind of. My 33 year old Q-jet ran much better. I will go and buy a new carb on monday but it won't be another Holley!
I don't like it all!!!
I've put the yellow spring in and didnt make any difference (there is only 1 step lighter, white). Also it doesnt idle well at all. In fact the idle goes up and down beetween 1100 and 700 rpm's and no I don't have any vac leaks. It doesn't start well when warm. The choke is worthless (electric and yes I do have power to it) The carb's only redeeming factor is it looks very nice.
I understand that to achieve maximum or optimum performance a new product may require some adjustment. But the thing should run fairly well out of the box. This one runs kind of. My 33 year old Q-jet ran much better. I will go and buy a new carb on monday but it won't be another Holley!
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Le Mans Master
Joined: Mar 2002
Posts: 7,456
Likes: 2
From: Coming home from Luckenbach Texas
Re: Holley vs. Q-Jet (micks69)
Just to clarify: Edelbrock makes stock replacement QJets (spreadbore), and they make Edelbrock Performer (square-bore) carbs. If you're old enough, you'll remember the Performer when it was called a Carter AFB...
PS: I don't know why people rag on QJets. They're a versatile carb that works very well out of the box, and work fantastic when someone like Lars fiddles with 'em!
PS: I don't know why people rag on QJets. They're a versatile carb that works very well out of the box, and work fantastic when someone like Lars fiddles with 'em!
Melting Slicks
Joined: Apr 2000
Posts: 3,286
Likes: 8
From: San Jose California
Re: Holley vs. Q-Jet (micks69)
Ok, I was really trying to nice when I said the Holley was a good carb.
I don't like it all!!!
I've put the yellow spring in and didnt make any difference (there is only 1 step lighter, white). Also it doesnt idle well at all. In fact the idle goes up and down beetween 1100 and 700 rpm's and no I don't have any vac leaks.
I don't like it all!!!
I've put the yellow spring in and didnt make any difference (there is only 1 step lighter, white). Also it doesnt idle well at all. In fact the idle goes up and down beetween 1100 and 700 rpm's and no I don't have any vac leaks.
Chuck
Thread Starter
Burning Brakes
Joined: Aug 2001
Posts: 1,160
Likes: 3
From: Greensboro NC
Re: Holley vs. Q-Jet (page62)
Page62
I think I may try the new performer series (old carter I wish I wasn't old enough ;) )
Chuck,
My setup was working great before (I just had to keep fixing till ..... you know the rest)
Which would you guys put on? (I like the a nice surge when the secondaries kick in)
I think I may try the new performer series (old carter I wish I wasn't old enough ;) )
Chuck,
My setup was working great before (I just had to keep fixing till ..... you know the rest)
Which would you guys put on? (I like the a nice surge when the secondaries kick in)
Le Mans Master
Joined: Oct 2002
Posts: 5,714
Likes: 6
From: Silver City NM
St. Jude Donor '05-'07
Re: Holley vs. Q-Jet (micks69)
I can't wait to dump my Quadrajunk for a Holley. Note that Chevy used HOLLEY on their PERFORMANCE motors, and the Quadrajunk on their tamer engines. Anyone see Quadrajunk being used by folks at the tracks...other than restricted "stock/superstock" classes? Nope.
The main problem people have with Holleys is buying the right one for their car. They usually buy one way too big and then gripe because their secondaries don't kick open or it backfires when they floor it. Hot rodders seem to have a natural tendency to "overestimate" the actual power being put out by their engines. Also, duoble pumper Holleys will slam all four barrels open at once, but they are really more suitable for a stick shift than an auto.
Dep...aka Old Geezer
[Modified by Ex-Deputy, 10:36 PM 10/12/2002]
The main problem people have with Holleys is buying the right one for their car. They usually buy one way too big and then gripe because their secondaries don't kick open or it backfires when they floor it. Hot rodders seem to have a natural tendency to "overestimate" the actual power being put out by their engines. Also, duoble pumper Holleys will slam all four barrels open at once, but they are really more suitable for a stick shift than an auto.
Dep...aka Old Geezer
[Modified by Ex-Deputy, 10:36 PM 10/12/2002]
Thread Starter
Burning Brakes
Joined: Aug 2001
Posts: 1,160
Likes: 3
From: Greensboro NC
Re: Holley vs. Q-Jet (Ex-Deputy)
I can't wait to dump my Quadrajunk for a Holley. Note that Chevy used HOLLEY on their PERFORMANCE motors, and the Quadrajunk on their tamer engines. Anyone see Quadrajunk being used by folks at the tracks...other than restricted "stock/superstock" classes? Nope.
The main problem people have with Holleys is buying the right one for their car. They usually buy one way too big and then gripe because their secondaries don't kick open or it backfires when they floor it. Hot rodders seem to have a natural tendency to "overestimate" the actual power being put out by their engines. Also, duoble pumper Holleys will slam all four barrels open at once, but they are really more suitable for a stick shift than an auto.
Dep...aka Old Geezer
[Modified by Ex-Deputy, 10:36 PM 10/12/2002]
The main problem people have with Holleys is buying the right one for their car. They usually buy one way too big and then gripe because their secondaries don't kick open or it backfires when they floor it. Hot rodders seem to have a natural tendency to "overestimate" the actual power being put out by their engines. Also, duoble pumper Holleys will slam all four barrels open at once, but they are really more suitable for a stick shift than an auto.
Dep...aka Old Geezer
[Modified by Ex-Deputy, 10:36 PM 10/12/2002]
Le Mans Master
Joined: Oct 2002
Posts: 5,714
Likes: 6
From: Silver City NM
St. Jude Donor '05-'07
Re: Holley vs. Q-Jet (micks69)
micks69: Is your car stick or auto? A stick can SOMETIMES get away with being overcarbureted by bringing the revs way up and then dumping the clutch.
The 350/350 is NOT the same as a 350/370. If I remember right the 350/370 is solid lifters with a hotter cam.
A much better carb for you would be a 600-650 cfm Holley.
The 750 you bought would be real nice on my 454 after I get a hi-rise and aluminum heads. I wouldn't even try it on mine now and I have the valve size and cam to use that kind of carb.
P.S. Where did you expect all that air you suck into the engine to go with those factory exhaust manifolds on there???? ;)
[Modified by Ex-Deputy, 11:05 PM 10/12/2002]
The 350/350 is NOT the same as a 350/370. If I remember right the 350/370 is solid lifters with a hotter cam.
A much better carb for you would be a 600-650 cfm Holley.
The 750 you bought would be real nice on my 454 after I get a hi-rise and aluminum heads. I wouldn't even try it on mine now and I have the valve size and cam to use that kind of carb.
P.S. Where did you expect all that air you suck into the engine to go with those factory exhaust manifolds on there???? ;)
[Modified by Ex-Deputy, 11:05 PM 10/12/2002]
Team Owner
Joined: May 2001
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From: Exiled to Richmond, VA - Finally sold my house in Murfreesboro, TN ?? Corner of "Bumf*&k and 'You've got a purdy mouth'."
CI 6-7-8 Veteran
CI-VIII Burnout Champ
St. Jude Donor '06-'10, '13
Re: Holley vs. Q-Jet (Ex-Deputy)
I have always like Edelbrock and QJets over Holleys. Holleys you can change more, and are sometimes easier to adjust, but you always have to adjust them.
The Edelbrocks and QJets by design are a more "load sensing" carburetor. The rear upper doors on the secondaries only open by being pulled open by the engine. And those set the metering rate. You only have to adjust mixture for WOT on the rears and once that is set, you just adjust the tension on the spring for when they open and how fast they open.
I gave up on all that crap and am going to try fuel injection next month. I am tired of trying to chase mixture all the time. Let the O2 sensor and computer deal with it for me.
The Edelbrocks and QJets by design are a more "load sensing" carburetor. The rear upper doors on the secondaries only open by being pulled open by the engine. And those set the metering rate. You only have to adjust mixture for WOT on the rears and once that is set, you just adjust the tension on the spring for when they open and how fast they open.
I gave up on all that crap and am going to try fuel injection next month. I am tired of trying to chase mixture all the time. Let the O2 sensor and computer deal with it for me.
Le Mans Master
Joined: Oct 2002
Posts: 5,714
Likes: 6
From: Silver City NM
St. Jude Donor '05-'07
Re: Holley vs. Q-Jet (BSeery)
micks69: a Holley and Quadrajunk are VERY different carbs. Note the size of the primaries in a Holley as compared to the GM carb. They are TEENY TINY to promote economy when running on the front two barrels. The also flow considerably less air than Holleys. If you purposely searched for a worse combination for street use than the one you put on your 350/350 engine, I don't think you could find one worse than the one you got.
That is NOT to say that those aren't excellent parts. They just aren't for your engine combination. That is a VERY high rise manifold. I know because I used to have that manifold on a 71 Nova. That manifold doesn't start working well until you hit ABOVE 4000 rpm. It's a top end manifold. And in combination with that large carb on a hydraulic lifter engine with only moderate sized valves (if you have an automatic things get even worse),
it simply WON'T perform like a Z-28 302 or LT-1 engine. I had a double-pumper 750 on my Nova, but had a stick shift. So I could bring the rpm up and ease out the clutch or bring the rpm WAY up and pop the clutch.
Dep
That is NOT to say that those aren't excellent parts. They just aren't for your engine combination. That is a VERY high rise manifold. I know because I used to have that manifold on a 71 Nova. That manifold doesn't start working well until you hit ABOVE 4000 rpm. It's a top end manifold. And in combination with that large carb on a hydraulic lifter engine with only moderate sized valves (if you have an automatic things get even worse),
it simply WON'T perform like a Z-28 302 or LT-1 engine. I had a double-pumper 750 on my Nova, but had a stick shift. So I could bring the rpm up and ease out the clutch or bring the rpm WAY up and pop the clutch.
Dep
Melting Slicks
Joined: Jun 2001
Posts: 2,340
Likes: 2
From: Moro IL
Re: Holley vs. Q-Jet (micks69)
I'm with most of the veterans here. If you were pretty happy with the quadrajet, stick with it. People who knock quads are people who can't tune one, or try to make them do things beyond their design. A quadrajet adjusted correctly works wonderfully for a street car and even some mild strip duty. I had Lars set mine up and it's been great, both responsive and powerfull. Plus they are capable of flowing 750cfm, plenty for most engines, if you look at the engines that GM normally put holleys on, they were normally rated at 750cfm or more (LT-1 was a 780 holley, I believe), so it wasn't that GM didn't have faith in the quads as a performance carb, they just weren't right for the application. Normally if you have a holley and a quadrajet both setup pretty close to where you want them the holley will make a little more power but the quad will tend to get the better mileage and tend to be less fickle. My recommendation would be to find a good carb shop to rebuild your stock quad.
:cheers:
Pat Kunz
:cheers:
Pat Kunz
Le Mans Master
Joined: Sep 2000
Posts: 5,635
Likes: 4
From: Orlando Floriduh
Re: Holley vs. Q-Jet (micks69)
Q-jets are great but... They MUST be set up exactly correct for your application. So if you have the original carb and you car is stock.. you have a good set-up.. Once they go through a commercial rebuilder they become the famous Quadra junk everyone hears about. There are hundreds of variations so you never get a carb that is sexactly correct. When you get a new one from Edelbrock it is usually is set up pretty good for the average user.
[Modified by silvervetteman, 5:48 AM 10/14/2002]
[Modified by silvervetteman, 5:48 AM 10/14/2002]
Safety Car
Joined: Feb 2002
Posts: 3,556
Likes: 0
From: Seattle WA
Re: Holley vs. Q-Jet (silvervetteman)
I like these ones. :jester
sorry couldnt resist. on a diffrent note, when my engine was 1st built it had a freshly rebuild q-jet. kinda lacked in response so i decided i would switch and started researching carbs. well im glad i never switched it and just had someone tune it. i had the vaccum re-worked and the carb adjusted. instant response, and an overall great carb. i havent had experience with, Edelbrock, Holley, Demon, or any others, but my Q-Jet works great. maybe one day i switch, but it will be out of boredom.
Thread Starter
Burning Brakes
Joined: Aug 2001
Posts: 1,160
Likes: 3
From: Greensboro NC
Re: Holley vs. Q-Jet ('79ProwlerOrange)
Here is what I ended up with after calling Holley. A 0-4777C mech secondary 650 cfm with the 45-224 electric choke kit. I described the car to the guy on the phone and asked him what he would put on it. We'll see tommorrow!