EDIT: Sounds like caddyescalade has an extremely similar experience with a quick fuel double pumper. His primary jetting has gone up and his secondary jetting has gone down as he has a rich condition under load and a lean condition at cruise. I think I'm just going to press forward and increase the jets on the primaries and decrease on the secondaries and have a 70 at all four corners.
https://www.thirdgen.org/forums/carb...-question.html

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After all these years Im trying to really learn and understand how to tune these Holley style carbs and make it work.

It's a quickfuel HR-650 carb - https://www.holley.com/products/fuel...t/parts/HR-650
It's got a 70 front and 74 rear jet out of the box with a 6.5 power valve.

I have a wideband Im looking at for all my cruise and transition tuning and the problem I'm having is that it seems to go a little too rich at WoT, and I feel like it's far too lean at cruise, it's about right at light throttle under load when the power valve opens, and it's right in the middle at idle where it's tuned to run smoothest with most vacuum. So here is the current indicated AFR's and conditions, and current calibration:

Idle: 12.8-13.2
Light Throttle, medium load (power valve): 12.0
Cruise:14.9-15.3
WOT: 11.5-12.0

Current primary jets are 69s, current secondary jets are 71's, power valve is still a 6.5 but Im thinking I might throw a 7.5 in to try it. ( the 8.5 seemed a little too eager to dump fuel and it ran pig rich constantly) Both the primary and secondaries are set where the transition slot is barely visible, more or less "square".

I've been progressively trying to richen the cruise AFR and lean out the WOT AFR, and that has gotten me to the 69-71 jet combination I currently have in there, and it's been moving the right direction with each adjustment. My last change was moving from a .070 to a .055 Idle Air bleed, and that dropped my cruise AFR around .75 points to right around high 14.8-15.2. When it was hitting 16's I could get it to do lean pops sometimes, but it's not now.

So my issue is that assuming the AFR gauge is accurate (and I have no reason to believe it's not. When it runs lean the car acts lean, when it goes rich it matches what I'm hearing/smelling and seeing out the tail pipe), it sounds to me like I need to go to bigger jets in the primary, and maybe even a smaller jet in the secondary - which gets me to a 70/70 jetting. Is there any scenario where that makes sense? Should I go to an even smaller idle air bleed since that helped? Should I just trust the process and square jet it?

I assume the power valve is working because I can drive it at light throttle to a nearby slight hill that loads it up just enough that the AFR drops from about 15:1 to 13.5-13:1 - is this conclusive that hte power valve is working, or could that just be booster signal? Note when I put the 8.5 power valve I had laying around in there, the thing seemed to just be generally too rich all the time, which doesn't fully make sense, but it seemed like it was just way too sensitive and opened too much, but I cant remember if I made any other changes at the same time or not. But I was seeing 10:1 and 11:1 sometimes under moderate loads so I got rid of it and put the 6.5 back in.

I feel like Im taking the right approach to all this, and I'm just worried about why I seem to need to make changes that are so far from the out of the box calibration.

 

What intake manifold are you running this on? and what is your vacuum at idle?
Does your carb have the normal progressive linkage to the secondary so that normal driving is only primary side only?

 

For what it's worth I have a 750dp and followed Sofa's tuning sticky (minus the part about actually changing out the jets, etc.) and with the parts it came with stock (which I think is a 6.5 PV, 70 primary and 80 secondary) and it runs great. Tuned it with a vacuum gauge.

Of course that was years ago and I've slept since then so I don't remember the specifics but what I do remember is that when I cross referenced the serial # I was able to confirm that it had whatever size parts in it that Holley put in it from the factory (carb was bought lightly used).

 

Yes it's a progressive linkage.

For whatever it's worth I think a 7.5 power valve plus leaner primary jets are the solution here. I swapped back to the 8.5 and went to 67 primary jets and it might be the best this car has ever run, seems to just be spot on in most situations. It's going rich a little too early at light load, so I think a 7.5 PV will probably be the right balance.

Idle vacuum is somewhere around 14"