How can I tell if my outboards are opening on a six pack?

There is going to be several factors that determine when the outboards come in. I use yellow springs which a factory springs I also use a fairly gnarly hydraulic cam but I guess to keep it fairly straightforward I would say generally at wide open throttle around 3,000 RPMs. The outboards butterflys need move freely.- the diaphragms will fail I've had to replace mine once. If you don't think you're outboards are coming in then they're definitely not. You would know.
Thanks. I replaced the diaphragms about 10 months ago after I rebuilt the carbs. What I didn't do when I had them apart was clean or replace the throttle shafts, and I'm thinking I should've.

I tried the test from Harold Demes' video, but I couldn't get too far, because I ended up with a mist of fuel spraying back out of the throat of the carb.