Quadrajet Problem Solving > Quadrajet Parts and Numbers

Quadrajet Selection

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oldschoolss:
Hello Guys,

I have a 1962 327 that I want to put a quadrajet on along with vortec heads. I have a couple quadrajets laying on the shelf, I think two are off 75 or 76 BOP applications. Both have the heat riser choke but they also have a terminal coming off them... Anyways I took the one that's a 800 cfm unit to a friend to help me rebuild it. He told me not to use it as all the 75 and later carbs as they are not good as they are very picky and have lots of drivability issues.

Is this true? I was thinking of rebuilding the 750 CFM unit for my 327. I can pull the actual number tonight, I'm pretty sure it was a 75 model.

Thanks,

Scott

Cliff Ruggles:
Scott, the later carburetors made in and after 1976 with the later style APT feature are actually superior to all previous designs in every area.

They are just a tad lean as they were produced under tighter emission standards than the older models.  If you plan on using one of them outside of it's original application (obviously), get one of our books and use the rebuilding chapter for complete/correct rebuilding, and the high performance chapter to recalibrate it exactly for the application.

We sell complete/correct rebuild/tuning kits for the later units.

BTW, I use a 1977 Pontiac carburetor (part number 17057274) on my 455 engine that powers my 1973 Ventura.  The car runs low 11's in full street trim on DOT tires.  We dyno and track tested the carburetor against a Demon 850, Holley HP 950 and a Holley 850 DP carburetor.  The Quadrajet made more power on the dyno and outran the other brands on back to back testing at the dragstrip.  Although the magazines did not cover all the test results, some of the information made it into High Performance Pontiac and Popular Hot Rodding's Engine Masters edition a few years ago.

The Quadrajet we used was not ported or altered in any way by grinding or sanding, bead blasting, etc.  It was an as cast unit with upgraded tuning parts, completely blueprinted/recalibrated with performance modifications as outlined in our book......Cliff

jxu109:
Too bad there isn't more data in the magazines on Qjets vs Aftermarket carbs, but I suppose that would really upset the advertisers of the magazines.

Cliff Ruggles:
It's all about politics.  We have found over the years that you are allowed to compete with aftermarket parts, but not allowed to outrun them. 

Consider this.  Magazines catering to the high performance industry are filled from front to rear with advertisements, telling us how much better all the shiney parts are when installed on our older vehicles.  They pay for considerable advertisement space.  Any articles found in those magazines are not going to typically show that stock parts outrun the "high performance" parts.

Speaking specifially about the quadrajet, they are excellent for high performance use.   Two things have been working against them for years.  Very early units were HORRIBLE, leaking bottom plugs, POS fuel inlet valve assemblies, poor float hinge pin location, etc.

They quickly gave the Quadrajet it's "Quadrajunk" reputation, even though the factory corrected these issues by 1969.  At that time, fuel was cheap, so EVERYONE dumped the factory carburetors and bought a Holley 600 vacuum secondary carb, often a $75 Edelbrock intake to go with it.  Neither one of those parts made any more power than the stock ones, but you could at least put the Holley sticker in your window, have everyones eyes burning who got anywhere near the rear of your car, and do "donuts" in the  High School parking lot!

Even though a few of us figured out that the Quadrajets were excellent, the early 70's brought on very tight emission standards, and the carburetors we had access to were HORRIBLE, being so lean at idle/off idle they wouldn't work well on any "high performance" engine.

The bad reputation continued, and is still around these days, handed down over the generations, tyically from folks who's cars are held together with super glue and rubber bands, and no faster than a Dodge Neon with a plug wire or two pulled off!

Just making some humor here, but there is some truth between the lines.  When we race our car at local tracks, folks always come over to see what's lurking under the hood to make such a quiet daily driver so fast.  When they see the quadrajet, the look you get.....PRICELESS!

These days we don't hear nearly as much of the "quadrajunk" comments, especially when we are in final rounds at big races, running faster with our stock parts than folks with all the latest "bling"!.......Cliff

jxu109:
I've had plenty of people tell me that I can make make my qjet run pretty well (as if I didn't already know that), but if I want the best performance, I'll need to switch to a Holley or Edelbrock.

Sometimes I start an argument, other times I laugh and move on.   ;D

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