afb vs avs

[65TerrorCuda]

I'm sure it's been asked before, but for your money, today, what carb would you buy between the afb and avs? Is the avs worth the extra $$? Are carter/edelbrocks more resistant to boiling fuel versus a holley?

Neither is an okay answer too

[dodger1]

I would personally pick the AVS, mainly because of the easier adjustment to the secondary opening rate. Similar to my Thermoquad, in fact! Can't comment on the fuel boiling issue, though, TQ's don't do that!!

[George G. Leverette]

They are completely different carbs designed for different applications. The engine is a system that demands a specific air fuel mixture to operate at its maximum efficiency. The casrb should be selected to meet the demand.

[pcrmike]

What George is trying to say is that the street engines, like MPG, torque, and driveability. The fact is the AFB is a rock-solid performer in this area. The other fact is that the AVS is virtually the same carb with an added feature, largely helpful for drag or acceleration runs from a dead stop, called an adjustable secondary air door. For performance on the daily driving, the AFB is tough to beat, and the AVS is about as good. Feed the correct CFM for the application, and you should be fine. Remamber, AVS is better for strip or hot street. :-)PCRMike

[65TerrorCuda]

Thanks for clearing that up Mike, your explanation was exactly what I was looking for.

[DartGT66]

Actually, the factory AVS carbs had different style fuel rods than AFB's, and provided amore sofisticated fuel curve if tuned right. The Edelbrock AVS is exactly the same carb as a federal mogul or edelbrock AFB, the only difference is in the air trap door. The AFB uses a counterweighted door; when the force of the vacuum above the secondary throttles becomes greater than the force of the counterweight pushing the door close, it opens. In the AVS, the air door is controlled by a pre tensioned sprimg, and it's adjustable by changing the pre tension. In my opinion, the Edelbrock AVS is way better than the AFB. It's just the same as the AFB, but you can alter the opening of the secondariese easier. Either making them open quicker, which with more fuel from the accelerator pump gives better performance, or slower, which can give better fuel economy. As far as I see, there is no drawbacks with the AVS.

[pcrmike]

Ditto that, Dart. I forgot about the factory Carter AVS being a little different. :-)PCRMike

[Dart]

The AVS is easier to tune. AVS stands for Air Valve Secondary. To get the AFB working correctly you will need to drill or modify the counterweight in the secondaries. On the AVS you just need to adjust the tension for the secondaries on the spring that controls the air valve.