Help with Q-Jet

[Cubman]

I have a '78 K10 with a 400 small block and th-350 auto.  I got a bunch of water in my gas and ended up having to rebuild the carburetor to get the truck running.  The carb is a 4-barrel Rochester with the divorced choke (#17057213).  The choke operates flawlessly, and the truck runs great until you really get on the gas.  When the secondaries begin to open (I think), the motor will bog instead of making more power.  Afterwards, the truck will not run as smoothly until the next time it is started.  This problem did not exist before I rebuilt the carb.  I made a video to give several examples of this happening.
http://www.youtube.com/watch?v=Jfwk0f9JKLs

I used all the new parts in the carburetor rebuild kit, the float is brass and was not leaking, I epoxied over the well plugs on the bottom of the float bowl, tested the choke pulloff vacuum canister, there are no evident vacuum leaks (all new rubber vacuum lines), and the fuel pump and distributor are new.  Compression is good across all the cylinders.
I am running out of patience with this carb and would appreciate any advice.  If you need more specific details please ask.

[ccz145a]

Tighten the spring windup on the secondaries. There will be a little set screw to loosen then turn the spring windup little by little until you feel it takes effort to open the secondaries. I wont take much, try 1/8 to 1/4 turn increments and not more than 1 full turn total. This will delay your secondaries until the vacuum of the engine opens them. Check that this little spring is not broken.

[Cubman]

This is on the rear passenger side of the airhorn, right?  The truck sits at my house 80 miles away while I'm at school. I will try tightening the spring this weekend.

[ccz145a]

right

[Cubman]

Alright, I got a chance to look at the carb this afternoon.  I see the slotted set screw, but what is the spring windup?

Edit: Found this in a google search, it gives a detailed procedure:
http://forums.corvetteforum.com/c3-tech-performance/494996-rochester-quadrajet-question-which-size-metering-rods.html
I will try this tomorrow and report back.

[Cubman]

No luck with the secondary windup spring.  I tried 7/8 turn, and 1 1/4 turn.  Changing the spring tension increased the rpms when the truck began to bog, but it would still happen when the secondaries opened.  Any other ideas?

[HAULIN IT]

Cubman, If the spring windup changed the point in which the bog happened, you should vacuum test the choke/secondary pull-off & the hose going to it again...this controls how fast (in a matter of seconds) the airdoor goes from closed to fully open. If it opens too fast, you get the famous "Quadra bog"...a lean condition. Your description originally didn't sound to me to be this (the part about it running bad until you shut it off & then start it latter), but this latest post does sound like the pull off. Did it still act up each time after you opened the secondaries while changing the tension on the door? Lorne

[Cubman]

HAULIN IT, the truck has the same problem whether or not the linkage from the choke pull-off is connected.  I will test this next time I am home.

[HAULIN IT]

HAULIN IT, the truck has the same problem whether or not the linkage from the choke pull-off is connected.

EXACTLY! This is what makes me feel the pull-off/hose to it...is bad.
 Forget the "Choke" part of it's function for a moment. I'd like to call it a vacuum chamber in hopes it helps you understand what it supposed to be going on with it. It's job is to HOLD the secondary air door shut until a low/no vacuum signal lets the door open because the chamber can't hold it shut any longer. How fast the door opens can/is controlled by how fast the vacuum "escapes" the chamber along with the spring wind up. I have modified some to release the door completely in a few seconds (along with modifying the secondary fuel enrichment). Originally there were many different part numbers & some had different times based on the vehicle they were installed on. Now you pretty much get what the A/M gives you & work from there (10-15 seconds). When the chamber/hose is defective, the holding function is gone & the door just flops open (you would get the same result if you take the linkage off) when the air rushes across it once the secondary throttle blades are opened...This creates a sudden lean condition that can't be "covered up" by the secondary fuel enrichment. Check it out! Hope this helps you, Lorne