1969 C10 Holley Carb help please

[csfdfirefighter]

Hey guys several years back My grandfather gave me his1969 C10 that he had originally purchased off the lot. Over the years I’ve slowly been trying to educate myself about the truck and give it the care it deserves. Most recently it wouldn’t start and I was able to troubleshoot it to the fuel pump not delivering fuel to the carb. The truck starts great now but my newest issue is that upon acceleration it wants to hesitate a bit before taking off. After reading as much as I can fine and watching videos it seems like it may be the accelerator pump nozzle needs to be sized down. Once I started digging in I noticed that there was only one Accelerator pump nozzle which is different than everything I see in the pictures. The other one appears to be missing. I’m not sure what this means or if this is acceptable. I’ll include pictures but any help would be great thanks so much guys/gals.
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[geezer#99]

Not a Holley expert but the accelerator pump nozzles are in the primary side. I think the nozzles are removable to change sizes.
Your circle is on the secondary side.

Have you checked your float levels?
Have you checked the pump lever setting?

[geezer#99]

Some info here.

https://www.holley.com/blog/post/hig..._instructions/

[csfdfirefighter]

Originally Posted by geezer#99

Not a Holley expert but the accelerator pump nozzles are in the primary side. I think the nozzles are removable to change sizes.
Your circle is on the secondary side.

Have you checked your float levels?
Have you checked the pump lever setting?

I checked the float level some time ago. I found these instructions for doing the pump lever but the instructions describe “First, make sure that the fast idle cam lever is disengaged so that the operating lever opens all the way.” I’m not familiar with what the fast idle lever is.

Any pictures I see of a similar carb on the internet shows another accelerator pump nozzle on the secondary side.



https://www.holley.com/blog/post/how_to_cure_carburetor_stumble/
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[geezer#99]

High idle screw is on the choke side.
They want you to be sure the primary throttle is full closed so the clearance can be checked accurately.
Vac secondary carbs don’t usually have a secondary pump.

[Ben IV]

Originally Posted by csfdfirefighter

I checked the float level some time ago. I found these instructions for doing the pump lever but the instructions describe “First, make sure that the fast idle cam lever is disengaged so that the operating lever opens all the way.” I’m not familiar with what the fast idle lever is.

Any pictures I see of a similar carb on the internet shows another accelerator pump nozzle on the secondary side.



https://www.holley.com/blog/post/how...retor_stumble/
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Fast idle lever is part of the choke. Brings the idle up when the choke is closed.

Your carburetor is a 670 street avenger. Great carburetor I've had the same one on 2 different trucks. It is a vacuum secondary carb so only a discharge nozzle and accelerator pump on the primary side. The pictures you see with 2 are mechanical secondary carbs "double pumpers"

Holly has some great videos on tuning their carbs. You may be able to fix your hesitation by changing the pump cam. They sell an assortment and there is a chart showing which cams do what. I swapped the factory orange cam for a blue cam and it helped in my application. Your results may vary.