Rochester Quadrajet's

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Rochester Quadrajet Speadbore

Myth #18

The 1970 Buick GS 455 'Stage 1" utilized the 'rare' 800 CFM Spreadbore.

False.

The 1970 Buick GS 455 'Stage 1' utilized the standard 750 CFM Spreadbore
{Part #7040246}

But, the Carburetor was re-calibrated with;
* Main Jets .............. .068"
* Primary Rods ......... .042"
* Secondary Rod ....... 'AU' {.0530"}
* Mixture .................. Moderately Rich
* Rod Length ............ Long
* Fuel Inlet ............... .135"
 
How about, a Thermoquad thread? Q -jets are sweet carbs, this will not get much response here.....
 

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Rochester Quadrajet Spreadbore

Not to be laughed at.

The 1968 Chevrolet 396/350 and 396/325 HP Engines with 'Oval Port' Cylinder Heads
and 10.25 Compression feasted on the competition in the NHRA, especially in the 'Super/Stock' Division.

The #7028217 worked best with the 396 'Mid-Performance' Engines.

* Main Jets .............. .071"
* Primary Rods ........ .045" {Manual}
* Primary Rods ........ .047" {Automatic}
* Secondary Rods ..... 'AK'
* Mixture ................. Rich
 
RustyRatRod said:
Never seen a quadrajet on a Ford of any kind. They had the Holley and several different Motorcraft (Autolite) four barrels. The 429 and 460 used the same carburetor as the Clevelands early on which was a couple different versions of the Autolite 4300. Then, at some point, they switch to the Thermoquad on the 460. That's all I've ever seen......but that certainly doesn't mean they didn't use the quadrajet.
Click to expand...

Here is one on ebay Item number 301503923206 I also have an old friend with a 71 Mercury Cyclone With a 429 CJ engine years ago he pulled his and put a Holley on it. This is the only Ford product I know that used a Quadrajet

Brian
 
Like the one year only electric choke TQ on a Ford?
 
Rochester Quadrajet '750 CFM' Spreadore

Ford

Found both on the 1970 and 1971 ~ 429/370 HP 'Cobra Jet'
* #7040288 {Automatic}
* #7040287 {Manual}
 
It was strange that Ford used the Quadrajet, because their base plate pattern is completely different from the Autolite 4300 spread bore. Not even close. They were already using the 4300 and could have utilized that pattern easily, like they did on the 4V Cleveland. The 4300 can be just as effective as the Qudrajet or Thermoquad so I have to wonder why they went with the Quadrajet. Maybe something emissions that the others could not give?
 
Highly valuable Quadrajets. I have to wonder how many people have one laying in a junk carb box unaware what there worth. The intake manifold is different also.

Brian
 
bcschief said:
Highly valuable Quadrajets. I have to wonder how many people have one laying in a junk carb box unaware what there worth. The intake manifold is different also.

Brian
Click to expand...

That was kinda my point. Ford had to cast a whole nuther intake. They went TO the 4300 later on the 460 cause I HAD ONE. So that means at some point, they changed from the Q jet to the 4300.

Why we're even into this on a MOPAR site I have no idea. lol
 
RustyRatRod said:
That was kinda my point. Ford had to cast a whole nuther intake. They went TO the 4300 later on the 460 cause I HAD ONE. So that means at some point, they changed from the Q jet to the 4300.

Why we're even into this on a MOPAR site I have no idea. lol
Click to expand...

'Change of Pace'

I believe the Quadrajet 750 CFM was utilized on the 1970 and 1971 429 'Cobra Jet' for exactly what you stated.

* 1970 and 1971 {Mid-Size Ford and Mercury cars}
* 1971 {Pony Cars}

To meet the EPA emission levels at low RPM's.

For use with the 429/370 HP 'Cobra Jet' with the massive Intake Ports on the {DOVE-E} and {DIVE-AA} Cylinder Heads, and the 'Hydraulic' Camshaft.

The Cast Iron/High-Rise Dual-Plane Intake was also utilized for this combination.
 
It's funny though......the 4V Cleveland had even bigger intake ports than the 429 CJ, yet it still retained the 4300. I guess the extra cubes somehow forced the hand with the bigger engines to the QJet.
 
Nick,

The 1968 Corvette with the 327/350 HP Engine came thru with a Rochester Quadrajet Spreadbore.

Advertised with a 750 CFM Rating.

* Carburetor ......... #7028219
* Main Jets ........... .071"
* Primary Rods ...... .046"
* Secondary Rods ... 'AN'
* Mixture ............... Moderately Lean
 
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