Thanks for the video back in the '70s I built a69 Camaro drag car 427 tunnel ram mechanical cam 13 to 1 compression with two 800 CFM quadrajets my friend said it would never work it worked all right it screamed I got the car on the nines on race gas have a great day thanks for inspiration I can't build cars anymore but I enjoy your videos

For an Emissions Carburetor, the Quadrajet more than holds its own. Thanks for this feature Andy!

Used to enjoy tuning Q- Jets because the results where rewarding,,the 850 cfm Q Jets especially...

I'd say that is a pretty stellar win for the OEM spreadbore Q-jet that it made close to the same power as a modern "race' carb. Q-jets definitely have their limits, but they're a pretty decent carb for what they are.

If the choke assembly is set right on the quad jet it's a beautiful cold start carburetor

Gotta love that Quadrajet plus it held its own. Not to mention you can still drive around town with the small primaries and not stop at every gas station. 👊🇺🇲

Have you asked David Vizard to modify that Q-Jet? He wrote a whole chapter in his book How To Build Horsepower Vol. 2 (1996) Carburetors and Intake Manifolds on how to mod the Q-Jet. Chapter 8. Page 82-92. DV showed how to modify a Q-jet to over 1000cfm....

Hello Andy thank you for another great video. I made an incorrect comment a wyle back to a few friends, saying that KZfaq is for entertainment not for education as I have seen so many video's that show incorect methods or the person lacks mechamnical experience. when I was about eight I found some of my Dads old Car books in his garage I dusted them off and asked I could look at them, 28+ years ago the magazines ranged from HOTCAR, Cars & Car Conversions, Popular Mechanics & heaps of others from late 60's to the early 80s. Reading these magazines as a kid I became a real fan of one writter David Vizard, as a teenager with my fist job I started purchasing his books I have nearly all of them execpt the Chevy ones lol. So when I found David Vizard on KZfaq I had to take back what I had said about youtube. The man is an absolute Legend, I learned my lesson a long time ago, what he says is 100% correct every time. After watching David Vizard on here, I found your Channel & I Love it great viewing everytime.

Let's talk about the amazing sound that, only a Q-Jet can make, if you have never felt the rush of those huge back barrels its a hell of a rush.

I’d like to see a Dyno shootout of production carbs on same engine. Qjet Vs thermoquad vs Holley etc.

If the QJet is to rich change the metering rods, also most Qjets were 750cfm (small block) ,800cfm was a big block carb. I’d bet you had a 750. With out getting it in the right air fuel mix range it wasn’t fare to the QJet. With the right fuel air mixture the QJet would have matched the new carb. Qjets are awesome carbs people that don’t like them don’t know anything about them. I did many carb tests on my personal dyno years ago, my 1967 Galaxie 500 with a 390 it ran the very best with an 800cfm QJet! It would do 150mph like clock work and was very fast on a drag race . Every other carb I tried the car was slower! Thanks for the video! Go QJet ! And by the way 429 Cobra Jet came factory with a QJet so even Ford approved of them!

I think you are the 1st to dyno this carburetor at least from my search. Should be good content for a heads up shoot out.

Qjet when tuned right will hang with any carb

If you know about Q-Jets, you know. DV got me really interested in them in one of his early books.

Those Q-jets are awesome if you know how to tune them. They make great power, sound fantastic when the secondaries open, and the small primaries give excellent fuel economy.

Can't wait to see those carbs on the MIXED UP BOSS Engine

Very cool test, the only thing I would say we can confirm from this test is the Q-Jets are good street carbs but have a lower ceiling than a 4150 square bore carb. I'd like to see VRS vs traditional 4bbl holley 😂

I know you spent a lot of time on that vintage street dominator intake but I think that engine at that RPM range probably needs a Performer RPM Q-Jet or an RPM Air Gap. The RPM Q-Jet intake would still be pretty stealth. Or there's the cast iron bowtie/marine intake which is like the Z/28 or LT1 intake but for Q-Jet. I think your porting guy Charles Servedio did some videos on that being the king of stealth SBC manifolds (I have a couple if interested).

Back in the 70's we ran our old 396/360's and 396/325's with quadrajet carbs...were good carbs but us teenagers didnt know how to tune them...we'd turn a wood screw into the secondsry linkage turning them into mechanical secondaries... we had lots of fun with these setups but when we went for cam changes we would replace the stock cast iron and quad set up with an aluminum intake and 780 holley carb and never looked back....an old 396 made lots of power with just a few mods, and seemed like most the old 66 thru 70 SS chevells came with one

The right person can make them quadra Jets work

Something is not quite right on that Q-Jet. I made 502 hp with an 850 cfm on a performer rpm dual plane on a 383. It had a little over 1 in/hg at 6,200. Fully open the air door by hand, measure between the top of the airdoor and the center rear of the secondary air door opening in the airhorn casting. For maximum flow it should be 1.27" from the backside top of the butterfly to the airhorn casting. Also with the carb off, open the throttle blades up fully and make sure the secondary butterflies are not over centering and starting to close again. 3 in/hg does not make sense even for an 800 model. Cliff Ruggles and I talked about a 406 he built that had a Q-Jet and stock GM cast iron dual plane on it making over 500 hp.

Thank you Andy. Being a budget minded builder I thank you for showing what I’ve been saying about the q-jet? It’s a great street carb when rebuilt and tuned.

That's pretty impressive in particularly considering the relatively budget friendly build. I spent a bunch more money in hopes to get the same power with my 327. That crate engine look is pretty cool especially at 500 horsepower

Nice Dyno session Andy. Great Edelbrock carburetor test and results. Very impressive out of the box test. Thanks for sharing. Have a great day.

Oh and I love the sleeper look with the Targetmaster style stock valve covers.

Awesome video Andy. Thanks for your efforts and information. Cheers 🍻

I can appreciate an aftermarket carburetor over the original GM factory carburetors, with that being said, the quadrajet has always been an extremely reliable carb, as well as a performance carburetor and a daily driver for decades and i love their consistency of performance whether that be making horsepower, or the reliability of it's performance in everyday driving, cold starts or hot starts, its been a proven reliable carburetor for all purposes!

Great video that proves you don't have to spend a truck load of money on a small block to get big Power great small block everybody needs one like that nice carburetor that Edelbrock

I could have told you this 30 years ago...if they had made the VRS back then. I worked for "The Carb shop" for many years and have built 10s of thousands of carbs, dyno'd them, tweaked them, twisted them...etc. IF you know what you're doing, there has never been a better carb than the Q-jet.

Can’t wait to see you tune it for mixed up boss people need to see the in’s and outs of this carb being tuned as it has heaps of circuits that are tuneable especially off the dyno getting it all working on the street😊

Nick's garage canada 🇨🇦 no screaming but Air Fuel ratio 👌 500 hp VRS 4150

That’s pretty good for out of the box. You have to really know what you’re doing and figure your time involved to tune the Q-jet to get the same results. All things considered,time, effort, the Edelbrock is worth the money. Very impressive throttle response too. Excellent work Andy!

Another banger video! Awesome results and great job with that ole small block 🔥🔥🔥

What do the Fuel injection guys say " I don't want to pump the Carburetor to get it started😭" 😂😂😂

Thanks. This was good confirmation. :)

Great testing guys thanks

I had a good time watching this. Good fun.

Awesome vid👌🏼, thats very strong power n Tq such low rpm’s also👍🏼🏁

That sleeper might have something for em!

That's cool, thanks for sharing!

I had a 73 Chevy G 10 van.350 engine.350 turbo.B&M 2400 stall.373 gear.I had a 650 double pumper holley.It ran ok.I put a Q jet that I rebuilt.off a 1979 Impala. with a eldebrock performer intake.It was like it was set on fire.

Man I was standing right beside him at the Lincolnton crusie in yesterday and kept thinking “man I know I’ve seen this guy somewhere lately “ 😂😂😂🤦‍♂️🤦‍♂️🤦‍♂️

,,,,,,,,,,,Man ,,I've been waiting for this...............................thanks Andy....................

Now the price is going to go up 🤦‍♂️ on the Edelbrock carb. Sheesh. Thanks Andy.

Just the radius inlet and annular discharge boosters are worth power. Excellent video!

Cool test! Kinda figured that a racing carburetor would make way more power on the dyno but I was surprised at that fuel curve. If you really want to see just how different those carbs are try both of them on the street. You might actually be ok with the top end power loss of the quadratoilet when you get a taste of light switch throttle response.

I have found, the Qjet performs well on a dual plane intake. Just as well as a holley. I ran a well tuned QJet on a single plane, switched to a holley and lost a over a sec on my ET.

From what I remember a Qjet is awesome sitting still.... In a quarter mile the bowls run dry from the shift of the gas level in the bowls. This is more of a question about the issue, not pointing a finger I have a 1970 350/300 Qjet sitting in a tub right now awaiting a rebuilt Qjet swap or rebuild. I'm sure this has been addressed over and over, but this is 2024 and most up to date qjet build to date; I'd say...... Every single day people work with the Qjet seems to be a better day for those old carbs....

Great video Andy.

This is a great video. The old Quadrajet held it's own pretty well considering it's origins. As mentioned a couple times in the video the VRS had a manifold pressure advantage, which gives it a real advantage here. The probably slightly better mixture didn't hurt either. I would buy that VRS rather than mess with an old Quadrajet, but that's just me. I can see someone really concerned about original appearance using a Q-Jet.

I like the looks of the Edelbrock, and impressive over the hot quadrajet, great video/dyno comparison Andy

I put a large Q Jet on a 351 M ford Engine Stroked to 400 cu in.30 thousands over size .That engine ran great.I also put a GM Hei distributor modified to fit ford Engines. Only way to make a FORD run😅

You are comparing Apples to Oranges here! A fair test would of been Edelbrock Performer Series carburetor. A true comparison test would be Holley 850 Dbl pumper and the Edelbrock VRS-4150 race carb. I still like everything you show us, keep up the good work.

Love the Q-jet test.

I have the 650cfm VRS on my 429 Thunderjet. Couldn't ask for a better carb! Great video brother!

VRS 750 pays off by well thought out design features 😊

I built or modified several Q-Jets in the late 70s early 80s and the 850CFM Q-Jet made 481HP ON A STOCK LS6 Crate and 490 with a 1050 dominator , We never out a hand on the Holley, Never changed a jet !!! It never gave me a problem in 2 racing seasons ,I Spent weeks modifying the Q-JETS So much potential . If you have a Cadillac 472-500 with air ,remove the A/C Compressor get the Q-JET worked and use a 1 inch spacer to raise the carb. The factory intake is recessed to fit all the crap under that hood. What happens when you open it up full throttle the rear (secondary blades cut of most of the fuel / air to the cylinders .By raising the carb WITH A 1 INCH SPACER you will pick up a noticeable amount of power .but your sacrificing the A/C and your going to fabricate some kind of air cleaner or cut the hood ,raise the center 2 inches ,(you will need a donor hood) and raise the center ,Its not difficult just time consuming and find a good donor hood. I've made several

Comparing the vrs against an older engineered driver style carburetor was not really apples to apples. For only a 20 horsepower gain with recent technology and engineering, that old quadrajet performed exceptionally well. I've worked with quadrajets many times and they are very good carburetor when you know how to set them up. You can't bash the q-jet......

I like the Q jet for several reasons. And I used to love it when the secondary's opened up in my 78 Chevy van. I always had the top cleaner lid flipped over with the tallest filter I could get to hear when it kicked in It went into race car mode LOL That has to be valve float at full revs.

500 and 500 is stout numbers for an 'economy' build 400 SBC, no doubt.....and that is MY fav thing to do...take all the parts nobody thinks will make power and MAKE POWER!!

Thanks for this Andy! The Qjet hung right with the Edelbrock to 4000. Some tuning would close the gap. I run a Qjet whenever I can.... I've even used them on small block Fords 😮 I'm trying to figure out how all these companies are copying the Holley design? I figured they would have patents or something on the design.hb

Pretty impressive, considering the small cam, I wonder if you could do the pseudo 3 barrel mod they used to do

Q-jets are actually good carbs and one of the best things is they will stay running on side hills and can start on side hills as well

Those Edelbrock's look & do the biz. That quadrajet sure surprised me

I took a Qjet off my brother's old 454 truck and stuck it on my 383 and it stopped making the "chwWWAAAA" noise. Disapointing, but still ran great.

Through the whole curve!

That bsfc is impressive for an out of the box carby

Thank you for the videos. I have to ask, did you verify the secondaries on the Qjet were adjusted to open all the way? That may have helped the air/fuel lean out a touch if it wasn't opening fully and reduced the vacuum at WOT. Also, the change in the fuel curve from the QJet is a metering rod hangar and a pair of metering rods away from being ideal for the dyno test. I find Quadrajets often make best torque from 13.3 -13.6:1 with pump fyel.

Look at that, it picked up even at the load in on the dyno.

If the Quadrajet had the same A/F ratio, how much closer would it have been to the Edelbrock carburetor? Although some people wouldn't consider it, but a Chrysler Thermo quad is a monster on a 396 BBC. I'd like to see one on a 406. BTW, good video. Keep them coming

Pretty amazing Andy! 20 HP right out of the box. Wow! I'm just about sold... I really want to see how those things behave on the street with a more radical cam like what's in my 451. Looking forward to seeing them on Casper. They're expensive but I'm about a gnats ass away from just buying one LOL.

Lookin good bro! Love the test. Would love to see it verses a Holley 4150 next!

The new Edelbrock against the denominators I don't know that might be a fight to the finish like to see that

So far I like everything I see about the new VRS 4150. Still need to see how they do on a Tunnel Ram before I buy 2 Holleys.

Wow, I'm surprised. I thought there would be very little difference between the two. I think the freshly worked over QJet (replated maybe?) looks pretty cool, but disappointed to see that it's pulling 3" of vacuum at WOT halfway through the run - that's not cool. It's really not meeting the 800 CFM claim if that's the case. I"m a manual gearbox guy so I want the mechanical secondaries anyway...

impressive!

I was making the same exact numbers with my engine and ran a huge Q-Jet from a Cadillac that I had a wonderful man that is no longer with us. I believe that it was the biggest one that was on a 472 from back in the day and he hogged it out and played with it for 3 days. But I couldn't buy a Edelbrock like that back in the 80's

Dam!!!!! From the box! I have had my carb worked on for years and still haven’t gotten it right.

That thing is undoubtedly what my 440 needs.

I had a summit racing Qjet on a mild 355 and it ran great in the midrange to upper rpm but down low it ran pig rich and the fuel economy was about 8ish mpg, the idle mixture screws made no difference on the idle, I'd say the hole in the blade truck may have helped. The cam and intake combo was the issue I imagine it had a 240/230 .480" 108lsa cam and a original Torker with a 2" spacer adapter. I tossed the cheap Eddy 600cfm on the same combo spacer too and it ran absolutely beautiful and the mpg went to 13-14 or so but I did feel a power loss up top, I left the Eddy on because the small amount of gain wasn't worth it, I was my daily and it ran so good I still have it, it's getting a fresh short block in the near future I do want something else my absolute favorite carb is the Holley 650 double pumper spread bore Qjet replacement carb, I had the vacuum version of it also and I hated it. I also picked up a nice old 300-31 contrnder intake to replace the Torker.

Thanks Andy 🍺

Awsome! Big block power out of a small block. Have to ugly up that new carburetor a little bit lol. Maybe some patina magic lol

Looks like you're running out of valve spring pressure! Up the rocker ratio to 1.7 and add some better springs. With near equal torque and horsepower, this is a well balanced street combo, but maybe more cam and variable duration lifters (Rhoades) too, if you decide to dig deeper inside. Anxious to see what comes next!

Change the rods and the Q -Jet will make more hp.

A Quadrajet will do anything a Holley 4150 can do till the Quadrajet runs out of CFM. Then Big CFM Racing 850- 1085 cfm 4150 Holley 4,-bbl reigns Supreme. In the Pontiac V8 Performance Racing world many have obtained 500-750 Hp with a Quadrajet and many report up to 20 mpg cruising at 70-90 mph in Firebirds Trans Ams. Muncie 4-speed and a Quadrajet dialed in is lots of Street cruising Fun. Usually able to drive all weekend on 1 tank full of Gasoline. Best Holleys huge CFM I am a Fan of. I Csn report Gas Mileage is absolutely terrible a BLP Bo Laws 1085 cfm 4150 on a 520 Hp 455 WOT at 7000 rpms. Get maybe 1 mike per gallon only

Definitely gotta do a test against the popular carbs like Holley and quickfuel.

I would be interested to see how the vrs carburetor drivability wise is. I have plenty of Holly's that work great at wide open not so much at Cruise.

This test means what? A carb that's set up optimally will make more power irregardless of make or model. On the street, the spreadbore will actually work better in most cases. How often are you at WOT for more than a few seconds when driving? That's where the spreadbore Qjet shines, in that half throttle transition area that your gonna be in 90% percent of the time.

Been looking forward to seeing more on the vrs. I think the quadrajet could come closer to matching with some jetting and adjustments but no comparison to the new Edelbrock.

My only issues with the Q Jet were fuel boiling in the float bowl when heat soaked and running it out of fuel on the back end of a hard run. Put a 4150 on it and never looked back. But I do miss the Q sound. It has a home on an upcoming 350 build.

Thanks Andy for testing that Edelbrock, I haven’t seen much about it at all! So, I have to ask, any plans to jet the jet better?

I saw a 340 dyno yesterday on youtube . And it seem the 2 to 4 barrel transition was wrongly adjusted . I saw a huge lean spot during transition . From 2 barrel to 4 barrel . Also that 340 performed best when dyno vacuum detected stayed at zero the longest .

The VRS nosed over several hundred rpm lower and at a steeper angle..so peak it made more but if you have to shift sooner? We need to see this at track ,) Looks like the VRS needs a tweak to air bleeds for a touch more fuel up top and maybe 1 degree above 5900rpm...no reason the carb with less restriction should have rolled over that quick..unless the heads are out of air, but then again this is a small cam..... Lots to ponder thanks, you never mentioned what makes VRS a VRS? Even when I watched the tour video.... Thanks for the content

Quadrajet still dominates for practicability ease of build ability hands down number one and surpasses dependability like nobody's business race on Sunday drive it to work on Monday

I told you 😜. Right out of the box. I’ve got to get a second one so I can put a pair on my Galaxie

That VRS is awesome and I've wanted one ever since they were released. They spend millions in development and it shows. I'm ready for the price to come down and then I might pull the trigger. I'm curious how the VRS would fair against a same CFM AED carburetor.

The quadrajet is probably a 750 cfm. Get that carb to Cliff Ruggles. He wrote the book how to modify Quadrajets. Hat's off the the VSR for attaining a perfect fuel curve out of the box.

GM did their homework on the Q-jet. Look up Dominator carb on a dual plane intake. It’s surprising!

Would have liked to see results with some slightly leaner secondary rods in the Q-jet . Just goes to show you a $50 core , and a $25 rebuild kit can give results similar to modern aftermarket carbs costing hundreds of dollars.

Q-jet: Not pretty. VRS: Pretty. Andy: Not pretty. Me: Very pretty 🤣. (Happy Birthday Andy 😉)