Hi, looking for some help on the thermoquad linkages from the primary to secondary shafts.
The car is an auto, street 440 and recently spent some time getting the primary side running really well, but the primary to secondary transition is 'lazy' even after playing with the airflap position and spring.
However looking closer at the linkages (Summit rebuilt carb) it looks as if it is a manual carb as it has the small pickup arm for the secondary pump shot - what I hadn't noticed until now is that this arm also opens the secondaries a small amount (.200ïnch) and holds it there for a while until the secondary main link fully opens the secondaries.
I have the original carb which does not have the pickup arm and it opens the secondaries in one smooth motion. Do I need to remove this arm on an auto car? and what does the small opening do for a manual car?

thanks in advance.

I only know of the linkage having to rely on choke being fully open, before it lets secondary throttle blade open on full accel.

Update, I removed the top of my carb, for a float level tweak, and think I see the issue. With the top removed the small amount of secondary opening does not occur.
So what I think is happening is that the accelerator pump spring which pulls down pulls the accel pump link rod up which opens the secondaries a little BEFORE the primary/secondary link opens them. It is only a small amount until the spring forces balance, and can only occur when the primaries are at about 70% to 90%. Not sure if this can happen when driving but would explain my inconsistent AFR at the very top end of the primaries and lazy secondaries. My primary/secondary link is correct with both throttle plates hitting the stops together.

Comments?

Pictures?

Hi Rob, I elected to bend the "manual" arm out of the way and rechecked the linkages. No issues and now drives MUCH better, the secondaries pickup is much cleaner and consistent and I don't get an over rich at the end of the primaries. If I get a chance I might bend the arm back and try and take a few pics as its a bit of a strange one.

Update,
As a reminder this post is to try and get some advice whether the 'manual' linkage is good or not on an auto car, and should I try to get this working correctly?

I have added some pictures that I hope will explain this issues.

Pic 1 shows the linkage with the manual arm bent out of the way - currently runs well like this.
Pics 2, 3 & 4 were taken with the throttle in the same position.
Pic 2 shows a rubber sleeve simulating the arm bent back ( I did not want to do this yet)you can see that it is touching and moving the secondary linkage before the primary pickup arm (arrowed) contacts the linkage. It is the accel pump linkage that has moved the arm.
Pic 3 shows the accel pump in the fully down, spring loaded, condition.
Pic 4 shows the secondary throttle plates starting to open before the primary pickup linkage is engaged. Primaries are only open about 70%. If the throttle is further opened the secondaries stay at this position until the primaries open them as normal.

Hope this explains it, and more importantly, should I worry about anything on my auto car?

Ray