jaketerk

I have a Holley 4165 on my 1972 Vette, 350. The car doesn't idle well at all, so I'm taking it in to get the carb tuned up. The mechanic asked if I had the original Quadrajet because he said that it is a far superior carb. Is this correct, or is the Holley the way to go? I can either get the Holley jetted, tuned, and adjusted, or have the quadrajet completey rebuilt. Please help! Thanks

77Dream

I think the mechanic just wants the original q-jet because its easier to tune/adjust or he just doesn't know how to properly tune a Holley.

Schmucker

A qjet is a better carb, but run what you want to run.

Gordonm

A better carb for what. Performance wise the Holley will outdo the Holley. For everyday driving the Qjet provides good economy with its small primaries. I'll take a Holley any day for performance over a Qjet. If it was a daily driver I'd stick with a Qjet.

comp

he should be able to tune the Holley, is your car stock other than the carb.swap???

cw823

Thus the popular nickname "quadrajunk"....right?

marshrat99

I'll weigh in here also. Properly tuned, the Qjet is a great carb but so is the Holley. I really thinks that it is a personal preference thing. Don't let folk convince you that a Qjet is junk simply because they've never taken the time to understand them.

redwingvette

Is the Holley you have a spreadbore on the original manifold? Both carbs set up correctly work well for a street driver. Lars does wonders with a Q-jet.

BatManFire

I'm running a Holley 650 DP on my Vette. If I had it to do all over again I might go with the Qjet.

I got good gas mileage and it ran pretty good before it crapped out. IIRC I think the Corvette is a smaller carb and I heard some Pontiac's and Olds had a 850 cfm unit that gave really good performance and descent gas mileage if you could keep your foot out of it.

The Qiet has small primary's and LARGE secondaries. The Holley I have like most Holley's have all 4 bores the same size.

stingr69

I run both and I like them for different reasons. The q-jet is a very good carb IMHO. The Holley is a little less sophisticated but that is not a bad thing if you are tuning a special combination or figuring out a problem. The Holley requires less experience to tune. Not everyone can tune a Q-jet without experience or references to go by. I have a file that I took off the web that outlines a step-by-step way to tune a Holley and it is very easy. The Holley has WAY more available parts so service is less of a chore.

Holley supports the aftermarket and the racers where Rochester is where? You can go fast with a Rochester but you are on your own for the most part (if you do not have Lars on your speed dial. )

For a driver, Rochester is not a bad way to go. If I were building something more radical, I would grab a Holley off the shelf and my tuning parts box and have at it. Neanderthal design but it does work.

Just one man's opinion.

-Mark.

Ken74Conv

If quadrajets are such great carbs, why don't racers use them.
I've never seen a quadrajet used in nascar.
I've never seen a quadrajet used on local dirt tracks.
You don't see serious racers using them.
You almost never see one on a street rod.
GM was the prime user. They are good because GM says so,
I DON'T THINK SO!!

Barry's70LT1

Most high performance cars sold by GM in the late '60s and early '70s came from the factory with Holley's installed.

Quadrajet = Good
Holley = Better

Kid Vette

The Holley 4165 is a direct replacement for a Quadrajet. As such it is primarily an emissions carb and needs to be tuned for performance. I'm running one with a fairly radical cam and it seems to be working out OK. However, I plan to do some further tuning with a wide band A/F meter.

I'm sure QJs are also fine when tuned properly. I'm certainly not a carb expert, but I think Holleys are probably easier to tune to work with a modified engine. However we all know what Lars has been able acheive with a QJ.

70L46Conv4Sp

The 4165 is a spreadbore and I replaced my original Qjet with it in 1973 after giving up on getting the stumble out of the Rochester. I have rebuilt the Holley several times over the last three decades and it runs great. I believe I could probably do justice to the Qjet now with thirty more years of experience, patience and maturity behind me but I guess I'll just leave it in the Holley box that it's been in all these years. Maybe one of these days I'll pull it out and rebuild it and put it back on with the original air cleaner. I agree with the guys who say the Holley is a superior carb in most respects (especially hi perf). I believe that someone like Lars can really bring out the best in the Qjet and make it a great daily driver type carburetor. However, for the moment, I'm going to stick with what works for me.

kermit1654

I think we all agree, it is obvious that the argument must be made that the decontextualized Holley and the sociolinguistic Quadrajet ultimately obscures the relationship between carb and intake and changes the rearticulation of the corvette's power capacitance and inter-subjective motionalatitude measurements of torque.

Translation of the above: I think it means the Qjet is better?

MEGALADON

Well said

Boofers

QJet wins for fuel economy, emmisions and driveability.
Holley wins for wide open power and ease of adjusting.

QJETs come from the factory set up for fuel economy, emmisions and driveability. Since QJETs can be difficult to tune they get a bad name when guys try to use factory set QJets for thier beefed up engines. Holleys on the other hand are much easier to adjust.

NHRA Stock and Super Stock cars produce a ton of power using QJETs. Here's the thing - you have to make some substantial mods to the carb in order to setup the QJet for that level of performance, like drilling out fuel passageways for example.

They say that QJets have a lot more time and resources invested in thier development than Holleys...

HDIronman

Quote:

Originally Posted by Ken74Conv

If quadrajets are such great carbs, why don't racers use them.
I've never seen a quadrajet used in nascar.
I've never seen a quadrajet used on local dirt tracks.
You don't see serious racers using them.
You almost never see one on a street rod.
GM was the prime user. They are good because GM says so,
I DON'T THINK SO!!

True, you don't see them much on all out perfrmance cars. However, I have a friend with a 67 Camaro bracket car, with a q-jet on a sm blk. His best 1/4 time this year so far is 10.11. I also run a Lar's q-jet ut I drive my car alot.

74 vert

I'm in the planning stages, but I think I'm going to go with a Barry Grant with mechanical secondary when ever I get around to getting a 406 stroker.

thevetterisbetter

What he said.
Holleys are easier to tune on the spot. I like my QJet, took a while to finger it out, but once I did, no problems, really.