1972 cutlass 350 rocket thinking about geting a new performance carbarator what should I get. Holley? . Elderbrock? Suggestions plese

 

Elderbrock?

Jmo but the Quick Fuel "Slayer" is the best bang for the buck.

 

I'll be the first one to jump in from the Qjet contingent. Unless your engine is heavily modified the only thing you're likely to accomplish w/ aftermarket carb is a precipitous drop in gas mileage, even w/ vac secondary style.

At that, aftermarket carb should still be dialed in for your application. Why not have the Qjet (ASSuming that is your present carb) dialed in and/or rebuilt by an expert? There really is no more versatile & precise a carb out there for most street driven cars. No linkage, choke, air cleaner, supply line potential hassles or mods.

A carb measures air & meters fuel - the Qjet does it very precisely & is still a very competent performer, it just takes some understanding of the beast. If your engine is near stock & carb isn't quite up to snuff then a basic rebuild will probably bring it around. Modified engines just require some modifications & recalibration of the carb to suit their needs. If the air/fuel mixture is correct over a broad range from idle to cruise & transitions to optimal range under heavy to wide open throttle it doesn't much matter what carb is on there, any one will work but any one will need to be optimized for best results. The Qjet that came w/ your car can supply a 500 horsepower engine w/ fairly basic modification & still provide excellent drivability.

How about posting up your car's combo & your location so folks can offer you additional opinions & advice?

 

Factory type QJet
Performance cars such as the Corvette used them. Marine engines. Trucks.

Feeding a 350 should be easy.
Your calibration start point is right there in the Chassis Service Manual and/or rebuild sheet.

 

The reason I want to replace the carb is because mine Is junk and I thought that when I went to replace it I would get one with more juice!

 

There's no doubt the Qjet is versatile.

But some of you need to expand your horizons. For example the Slayer has an adjustable vacuum secondary, changeable high speed and low speed air bleeds, main jets, power valves, power valve restriction orifices, accelerator pump orifices as well as the pump cam and pump capacity. Lots of tunability. Moreso than even a Qjet.,

 

An expertly rebuilt Q-jet is more than a match for any of the aftermarket alternatives in a near stock engine. Also, most a/m are squarebores, so you need an intake or at least need to run an adapter. I got my kit and recipe from Cliff's HP. My 350 ran so much better than I expected that I almost cancelled by 455 build.

 

It does sound pretty nice, expecially if you were changing a lot of things!

 

Archer - If you are in the market for the aftermarket carb you may want to get in direct contact w/ cutlassefi as he is definitely up on what is avilable & would suit you.

Mark - I would love to broaden my horizons. If I had the money I would sell or scrap my stinky old carbs & have you build me up a nice port injected setup!!! But, alas that is not in my financial galaxy so I just keep tunin my relativey trusty old aluminum pot metal.

You gotta admit the Qjet is a hell of a carb when tuned nice even if it is getting long in the tooth & 40 years later the will to offer newer technology may just provide a sliver of improvement but it costs a lot more than a consciencious rebuild & a bit of dialing in. That Slayer sounds nice but it still has to be carefully spec'd in hope of hitting the application close & ideally would still need dialing in for optimum performance.

 

Street Demon, 625 or 750 cfm. An all new castings, improved version of the Thermoquad. Many tuning parts and polymer or aluminum main body available.

 

Specifically what is meant by "the carb is junk"?

I see a nice new Demon starts at $400
plus fiddling

For that kind of coin you can get a very nice rebuilt correctish carb or maybe one of the NEW NOS 1967 numbers will serve your needs. Good for another 30 yrs. Minimal changes required for fuel line, throttle hookup, choke, etc.

 

A bigger carb is not going increase your power, think very carefully on what you plan on doing to your engine. I've seen it happen too many times, people change the carb expecting a large seat of the pants increase in power, only to have the engine run like kaka and drink a lot of fuel. Engines should only be fed the amount of fuel it needs.

 

+1. Junk?
You mean sitting at the bottom of a barrel of salt water? Jackstand slipped and you dropped a car on it?
Or just not running quite the way you would prefer?

I'd drop $30-40 on a rebuild kit and a float (let the argument begin between getting rebuild kits from NAPA or from specialty places like Cliff's and Sparky's...), rebuild it, then decide whether you still think it's "junk."

Patience, Grasshopper.

- Eric

 

I say stick with the Q-jet , either rebuild the one you have or find a rebuilt replacement and make sure it's calibrated for your tune of motor . The other big thing is make sure you have no vacuum leaks it'll make tuning any carb a miserable experience.

 

I have to jump on the Holley band wagon, they are super simple to dial in, I have used them on everything for 30 years. I believe they build a direct replacement for your QJet or you can change the manifold and use a bunch of different models.

 

I rebuilt a stock 72 350 q-jet for my 70 455 for about $60 with a kit from Cliff Ruggles, a compressor, and a little patience. When it wasn't running quite right after the rebuild (it was pinging a little under WOT) I gave Cliff a call. He told me what to do to re-jet it a little richer on the secondaries and now it runs great. It's a lot less money than a new carb and I went from 8-9 mpg with a Holley to 11-13 with the Q-jet.

BTW Eric, I paid twenty bucks more but got good advice so it was well worth the extra $20.

 

I was tired of my Q-Jet bogging on my '72 Rocket 350. Couldn't get a decent rebuild anywhere, wasn't brave enough to try it. Went to the Holley 4160, 600 universal, had lots of problems (even caught fire!).

Bought an Edelbrock 1406, Q-Jet replacement, 600, electric choke. Took it out of the box, bolted it on and never looked back. Very happy with it.

 

The only problem with going with an Edelbrock is he will have to replace the factory manifold or go with an adapter.

 

Aren't you glad you asked, Archer?

- Eric

 

Oh yes, sorry....
Took the Edelbrock carb out of the box, bolted it onto the 1" spacer on top of the manifold and never looked back.

 

I have used and rebuilt a lot of carburetors over the years. Q-Jet, 2-Jet, Holley, Carter/Edelbrock, Thermoquad, Motorcraft, Predator, and they all work. The absolute worst rebuild I ever had to do was on a Holley governored carb with vacuum controlled primaries and secondaries. What a bucket full of parts that was! No matter which one you use it needs to be tuned to the motor. Properly tuned, the Q-Jet is probably the best compromise between power and economy because of the small primary and huge secondary butterflies but it is also probably the hardest carb to tune properly. I have heard them referred to as the closest thing to fuel injection in a carburetor. I dunno about that, but most other carbs compensate for tuning by adding fuel. They aren't as sexy as a chromed or polished aftermarket unit but Q-Jets do the job, and well. A stock engine and a rebuilt factory calibrated Q-Jet is a hard combination to beat.

Just my $.02 worth.

Hoist.gifHoist.gifHoist.gif

 

"Junk" meaning what? Carbs typically do not wear out, so unless someone has screwed it up by breaking things, it's hard for it to be "junk". Yes, the throttle shaft bushings can wear and cause a vacuum leak. This is easily fixed with new bushings. Unless there is serious corrosion inside the carb, it isn't "junk", just in need of a rebuild.

You'll be hard pressed to do better than a Qjet for an all-around street carb on a mildly modified motor. The Qjet is arguably the most sophisticated 4bbl ever produced - which is also the main reason why people crap on it. Most don't have the skills or patience to get one set up properly and end up doing more damage than good. Yes, there are aftermarket carbs that are better for performance motors assuming your priority is max HP at the expense of all else. Only you know what your priorities and intended usage are.

 

And ...

Don't forget to stay tuned for next weeks episode of :

Vacuum advance - ported or manifold ?.

 

I thought I spelled bad...being that your 15 years old you may want to concentrate on getting passed high school with some decent grades

 

Sorry, but this is TOO easy...

I think you mean "...being that YOU'RE 15 years old..."

 

Plus, it's getting "past" high school, not "passed."


I like that. Two grammatical errors in a message critical of someone for making grammatical errors. It's a good laugh for the day.

I'm the first to admit that I sometimes pick on people for making grammatical errors that anyone who has passed (note, this time, "passed" is the correct usage!) second grade shouldn't make, but I at least make sure that my comment's grammar is impeccable before submitting it.

 

Ha ha.

Now, see, Archer: If you don't pay attention in school, then in another half a century, you'll still be spelling funny like Ol' Granpa Pogo, there.

- Eric

 

yep...see what I mean!!!

 

And for sweeps we will ask the question...vacuum or manual secondaries.

 

I got a edelbrock 1406 600 Cfm used for $80 and I put it on today and did not reget a thing it works perfect it has WAY MORE THROTTLE RESPONCE NOW the only problem is the throttle linkage bracket I will have to make one or get a aftermarket one. 5 times better than the stock one!

 

So your QJ probably needed a rebuild and had a dried out accelerator pump diaphragm.

That would have been half the price, but considering you would have had to buy carb cleaner and a few other goodies probably, an $80 E-brock is not a bad choice, at a price that is darned close.

Keep the QJ, as you may want or need to rebuild it later.

I had one car that came to me with an E-brock on it, and it never caused me any problems. The consensus on here seems to be the same: It'll probably work well for you.

- Eric

 

English is not my strong point btw. you don't learn how to weld or how to use a plasma cuter in English class that's why I like shop class!

 

Plus the e brock is like a bolt on 5-10 hp compared to the stock q jet

 

Not if you spent the $40 for a rebuild kit

 

Who told you that?

- Eric

 

No one told me anything I know that the e brock, holley,are preformance carbs designed to increase hoarse power and be more efficient and I concluded that it would help some in preformance of my motor

 

The 1406 is the economy version you will need to build it to 1405 specs. I ran a 1405 well into the low 13's in my previous small block. The q jet is a great carb but the only upside to the e brocks and holleys is simplicity. The q jet across the board well tuned should out perform the 1406 . The q jets ability to meter fuel all across the board and I may add very efficiently is what makes it complex. The e brock is no bolt on 5 to 10 hp. I don't think any carb makes that claim . The engine will make power when it gets the proper fuel the engine demands under the driving conditons.

 

You have much to learn.

Stick around here, and you will.

We have a number of experienced engine builders here (I am an experienced engine fixer, who is fairly good with the theory, but have not built numerous engines like Mark or Brian or others), who will be happy to explain to you the many mysteries of engine performance.

From my basic level, though, let me say that a carburetor is a complex analog device which works from simple aerodynamic principles. Because of the laws of physics and the limits of manufacturing tolerances and design specifications, it is very difficult to build a carburetor that will do every part of its job well. Idling, cruising, acceleration, wide-open-throttle performance, hot and cold operation, and consistency at differing altitudes all need to be combined, and doing so requires compromises to all of them. Different carburetor designs choose different compromises, and consequently have different strengths and weaknesses. The QuadraJet and Edelbrock (actually Carter AFB) designs both do a pretty good job of this, but the QuadraJet is a more sophisticated design, which GM put a LOT of time and money into, and can give a bit more than the Edelbrock can, provided it is in good condition, and configured properly for the job it needs to do.

Both the QuadraJet and the Edelbrock are capable of providing more than enough properly atomized air/fuel mixture to your engine for it to perform at its best.
Neither one contains more horsepower than the other.

You have chosen to buy an Edelbrock in good condition at a good price, that works well.
That is good.
But remember that the QuadraJet can do as well, if not better, if properly configured and in good condition.

You should read the Rochester QuadraJet Manual in order to see not only how the QuadraJet works, but also how other carburetors work. It's worth the time.

- Eric

 

Sorry, but this is again a case of the uncalibrated "butt dyno". You spend money on any "upgrade", so you "know" you will feel a performance improvement. Back-to-back drag strip tests of properly rebuilt carbs of both types will likely tell differently. For example, you've now traded a 750 CFM Q-jet for a 600 CFM E-brock. By the way, the E-brock is simply a re-branded Carter AFB carb, the design of which predates that of the Q-jet.

Your money, your call. Just keep in mind that replacing the former non-functioning Q-jet with a properly rebuilt and adjusted 2bbl carb would probably have netted the same drivability improvement.

By the way, simply buying the latest "hot rod" parts and throwing them at a motor is NOT the best (or most cost effective) way to build HP. You need to assemble a set of parts matched to the engine and car, and tuned for your intended use. On the other hand, many automotive aftermarket companies have made a lot of money convincing people that buying the next trick part is exactly what they need.

 

Car craft did a carb test in which they proved a smal carb will make an engine feel "stronger" on the street . So putting on a smaller carb may lead to it feeling better but up on the top end you will give some up.