linkz761

Ok, so i just got my car running fairly well with a new set of spark plugs. Now im trying to tune my edelbrock 1406 carb. My brother said he got my car out on the road and got a little crazy with it, and he said he couldnt get the secondaries to open for anything. Im pretty sure it has mechanical secondaires, and before i put the carb on, i notices they wouldnt open when i gave it "full throttle." I figured that was normal because there was no vaccume or anyhting. Anyone got a suggestion as to why they wont open, and how i might fix it?

Apeiron

The secondaries won't open while the choke is closed.

linkz761

Ok, assuming while they were driving, the choke wasnt closed, since it was 95 degrees outside. Any other ideas as to why they wouldnt open on a hot day?

Apeiron

Why would you think they're not opening?

five7kid

iTrader: (14)

The throttle blades are opened mechanically, but air flow is controlled by an air valve above them. The purpose of the air valve is to allow the secondaries to come in smoothly. If you can feel them opening, something is wrong.

linkz761

"The throttle blades are opened mechanically, but air flow is controlled by an air valve above them. The purpose of the air valve is to allow the secondaries to come in smoothly. If you can feel them opening, something is wrong."

Is this something unique to the edelbrock carbs? When i had my cc-quadrajet running well, you could hear a large difference in engine noise when you opened up the 4 barrels.

Apeiron

You might hear the noise of the extra air rushing in, but five7's point is that you shouldnt' feel any changes when the secondaries open. The increase in power should be smooth and unnoticeable. If you can feel a hesitation or surge in acceleration, then they're opening too early or too late.

linkz761

Ok thanks for the replies. Im just going off what my brother said, so i thought id ask. Still gotta drive it myself and see how it does. CAnt do that till after finals! Summer school sucks, I wouldnt suggest it to anyone.

Apeiron

I should also add that since the Edelbrock Performer is a primitive 50 year old design, if the secondary air valve is opening early or late there's not a lot you can do about it without making modifications to the carb.

327_TPI_77_Maro

iTrader: (8)

Fixed bob weights aside, the primitive carter AFB is still a half decent and downright reliable carb.

Apeiron

Yes, half decent and decent by half. There's nothing particularly outstanding about its features or its flaws.

Sonix

iTrader: (1)

Fixed bob weight? In other words, you don't even have an air valve spring tension to adjust like on a q-jet?
... That would make it... inferior wouldn't it?

Apeiron

The AVS has an adjustable spring on the secondary air valve, but the AFB uses a fixed weight. In the old days when people still cared about the AFB, they'd modify the weights or they'd collect dozens of different air valves from the junkyard for swapping, sort of similar to the way they collect Qjet metering rods.