secondarys not opening

[Heath]

Hi Cliff,

[Heath]

Hi Cliff,

I finished up rebuilding my carb with the kit I just got from you. I bolted it on today, sbc with weiand 142 blower and a 4 speed.  My problem is that my secondarys do not open sometimes. It is quite obvious when they do and dont. when they open the car pulls like mad to redline and get about 5-6 # of boost, when they don't open I have it floored but don't get any boost but stay at about 6" vacuum
There is no choke and no lockout link.
I tried it with the pulloff vacuum line disconnected, I thought maybe the vacuum was holding them closed. same results but with bog when they do open.
If I step into it steady they will open, but if I smash it they will not.
I dont think it is an airdoor problem as I tried reducing the tension until it just barely stayed shut with the same results.
I also have the pulloff rod set so that it is just loose at idle, tried it looser but no fix there either.
it does not feel like the secondary butterflys are sticking, could it be in the linkage?
the best i can describe it would be, smooth in the throttle and they open. let off and back into it hard and they dont
I have decided it is miller time for today but if anyone can help it would be appreciated.

[Cliff Ruggles]

Do a static test with someone in the drivers seat to make sure the throttle is getting the carburetor fully open each time the accellerator is fully depressed.

Watch the secondary throttle shaft to make sure it opens each time and is not sticking.  It is probably sticking once in a while at the bottom shaft, not the airflap shaft. 

Check the airflaps anyhow, to make sure they do not contact the edges of the airhorn anyplace and cause it to stick.

Lastly, lubricate the spring and pin with grease, and both shafts with light oil, then try it again and see if this helps?.....Cliff

[Heath]

i will look at it more later this week and let you know what I find

[Heath]

problem solved, I did not find any binding or sticking.
for whatever reason the secondary throttle plates sometimes didn't open , or should I say reopen after a fast unload and reload. what i did was to remove the outer spring on the secondary shaft and drill through the spring holder and throttle shaft. I then tapped this for a 6-32 screw, inserted the screw and left the spring off. they now open all the time as the nice officer politely let me know. Yeah I took the car out and pulled a classic idiot move, sitting at the red light I did not look behind me before I took off. Three gears worth off rubber later and stopping at the next light I heard the blipping siren, I adjusted my mirror to look behind me and lo and behold.... Well he was a nice guy, he expained that it was the end of his shift and that I would be the last car he would ever pull over becuase he will be starting as a detective on monday morning. I congratulated him .He ran me through the system, gave me a verbal warning, and complimented my on my "obviously powerful car that I was having fun with"
Anyways, thank you Cliff

[Cliff Ruggles]

Good news!!  I was certain that modification would correct the problem......Cliff