[kentmurphy]

Cross posting. Post is on FirebirdNation but there is zero activity over there.

So I'm doing my first carb adjustment and I need some help. When adjusting the idle mixture screws, I can't seem to get the vacuum pressure to change. It hovers between 10 and 12 hg. See below.

https://1drv.ms/v/s!AkkAtTM66idB6HN8APtdsvBAqkSb

I used these procedures

https://www.youtube.com/watch?v=UPGLUsW5ZeE
https://www.youtube.com/watch?v=dJg8GTlnIH0

Here's a little about my engine.

Pontiac 400 block
468 stroker kit.
Comp Cam - 20210708_003529588_iOS.heic
Edelbrock Heads
Torker 2 intake
Quick Fuel SS-750 carb - 20210708_004121953_iOS.heic

Questions

What might cause the vacuum not to change when adjusting the idle mixture screws?
When adjusting the idle mixture screws can I just adjust one and then eventually the rest ... or is it best to adjust all when seeking the highest vacuum reading?

Thanks in advance!

[kentmurphy]

I think I'm getting the hang of this. I adjusted each idle mixture screw one turn clockwise which raised the rpm to about 1050 and the vacuum to about 14. I then adjusted the idle down and this is what I ended up with.

https://1drv.ms/v/s!AkkAtTM66idB6HRlh1KGZt1hGclY

I think I need to do a little more adjusting of the idle mixture screws to find the spot where the vacuum rises and then falls off.

Open to any advice and thoughts.

Thanks in advance!