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Discussion Starter · #1 ·
I’m hoping somebody has run into this issue before and can help out. A year ago I bought my brother-in-laws 62 impala SS. It has a mid 70’s 350 with a mild cam (very mild I put that in this winter) , Edelbrock EPS intake manifold and a 1406 carb. He explained when I bought it that when the secondary’s open the car basically dies. Get off the gas and vrrrooom off it goes. He attributed it to a bent gas tank pick up that he bent during an attempt to repair the gas gauge. Sounded reasonable, I’ve seen his work before; he’s not the best at repairs and is more concerned about fixing it fast as opposed to correctly.
So I figured no big deal,I’ll take care of this over the winter and finish driving it to cruise nights for the rest of the season. The tank is old so I’ll replace the pickup, gas tank, fuel pump and lines. All the items were readily available, inexpensive and fairly easy to replace. Besides all of it was 46 years old, the tank had quite a bit of sediment in it anyway.

So over the winter I replaced the Tank, fuel lines, Edelbrock pump(around 5psi), fuel filter, spark plugs, spark plug wires ,cap , rotor ,air filter and heads (don’t ask lol). Even after that it still dies when the secondary’s open! So I read up that it could be the small needle valves in the carb, Edelbrock makes a larger valve for this purpose. I ordered the larger valves, installed them and same problem!..

This occurs when the car is hot/cold cool or hot days, doesn’t matter. Nothing seems to affect how it runs. On the primaries it runs fine. I’m about to order a new (rebuilt) Quadrajet to replace it.

Is this carb just a piece of cr*p or am I missing something? Oh I replaced the gas cap too!
It is definitely a fuel starvation issue. As long as it’s on the primaries it runs fine, open it up and within 2 seconds bam just like it ran out of gas. Let up ,off it goes(when the bowl fills back up).

STUMPED!
Any help would be greatly appreciated!

Bob
 

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u ever check the float bowl levels? that or git a jet kit for it also check which accelerator pump setting u have on it did u tune the idle screws?
 

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Maybe check the fuel pump pressure, either with a gauge or just disconnect the fuel line and see how far it spurts (NASA approved method).

Do you have one of those clear fuel filters in line before the carb that you can see the gas? I put a Holley on a friends Seville and the inline gas filter would clog with rust from his bad tank, he had to clean the filter every few days.

Sounds like either not enough gas is getting to the carb or something in the carb like bad float level is low, the float isn't going up and down correctly, the float doesn't float...

I'm a Quadrajet fan, especially the pre emissions ones. Love the way you can swap the secondary needles in a minute and if you don't open up the secondaries it gets better gas mileage than the Rochester 2 barrel.
 

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Discussion Starter · #4 · (Edited)
Yup checked everything!

If you read the first post , i have replaced everything from the gas tank (inclusive) to the fuel pump and all lines in between!
Car runs fine all day if I dont open it up! as soon as i do , bwaaaaaaa,,,popp....bogssss then let off and in a few seconds back to normal.
I have checked floats 3 times including drop. Installed larger float valves from Edelbrock. Nothing seems to be amiss with the carb.
I have adjusted the accelorator pump (has no bearing on issue) , adjuster primary idle settings. Replaced secondary jets and rods/springs from edelbrock tuning kit. But I'm waiting for my adapter to slap my quadrajet on and see what happens.
Bob
 
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