For your Mopar Project! Carter AFB Carburetor

smitty_p said:
I still have some triple-taper metering rods that were used on Q-Jets for some Oldsmobiles.
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All Q-jet metering rods are multi-taper...primary and secondary. Rochester used different plastic cams and metering rod hangers to alter the secondary mixture and over 40 different metering rod profiles. The release time of the choke pullout is a critical - and misunderstood aspect - of tuning secondary response, as is the basic tension on the air valve return spring.

Once you figured out that Rochester put idle feed restrictions in the carb body for emissions, enlarging them allowed you to tune the carb for very high horsepower applications.

Having said that, we could still run circles around the Q-jet with Carter's Thermo-Quad.
 
JohnnyGoo said:
Same here Smittys.I got pretty good at rebuilding Quadrajets .Hollys bahhh childs play comparded to the Quadrajet.
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Q-Jet (to me) was the easiest of all to set up and had much more fuel efficiency when driven on the street.

Holly made their carbs ultra-rich to cover a wide range of applications and they took LOT of work to get them "right."
 
Robert Herndon said:
All Q-jet metering rods are multi-taper...primary and secondary. Rochester used different plastic cams and metering rod hangers to alter the secondary mixture and over 40 different metering rod profiles. The release time of the choke pullout is a critical - and misunderstood aspect - of tuning secondary response, as is the basic tension on the air valve return spring.

Once you figured out that Rochester put idle feed restrictions in the carb body for emissions, enlarging them allowed you to tune the carb for very high horsepower applications.

Having said that, we could still run circles around the Q-jet with Carter's Thermo-Quad.
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I have no doubt. At the time, back in the 90s, I was on an Oldsmobile list serve (kind of a pre-cursor to forums). That’s how I got into Q-jets (though I thought for production vehicles only Oldsmobile used triple-taper primary rods, whereas other GM cars used dual taper - but that’s just what I picked up from the list serve. I am certainly no expert on the matter! I defer to you.)

It was fun tinkering with them, though I never raced or tried for high performance applications. I was just goofing around for street use. I also had a Holley (the 1850, I think) which I’d use on my Cutlass sometimes.

I got this Carter carb because I was curious about them. But, I never installed it. It’s like getting a set of pickups that you never put into your guitar!
 
Robert Herndon said:
Q-Jet (to me) was the easiest of all to set up and had much more fuel efficiency when driven on the street.
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That’s for sure! Those tiny, triple-Venturi primaries just sipped gas.

But, a few times on an open road I’d get those massive secondaries open and could literally hear the howl!

Then, you could practically watch the gas gauge go down!
 
smitty_p said:
That’s for sure! Those tiny, triple-Venturi primaries just sipped gas.

But, a few times on an open road I’d get those massive secondaries open and could literally hear the howl!

Then, you could practically watch the gas gauge go down!
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I had an extensively reworked Q-Jet on my 1975 Firebird Formula.

When its "right" you never feel the secondaries open...

Do a You Tube search for "1975 Firebird Route 66 Road Test."
 
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