Secondary's going lean

[74zz430]

I'm running a 7044206 carb with a Mallory 140 pump with regulator set to 5psi. Cliff rebuilt/ tweeked this carb several years ago and it runs great except I cannot keep my A/F ratio from going lean. In high gear at WOT starting at 3500 rpms the mixture will be in the low 13s but as the rpms increase the mixture leans to low 14s by 6000 rpms. If running just on the primarys everything stays stable. I have switched to the richest setup I can use on the secondary's. B hanger and CC rods, I believe Cliff used a 130 needle seat. I have even slightly reduced the secondary air valve angle since Cliff made that adjustable, I had read that allowing it to open to far causes air disruption in the secondarys. Any suggestions?

[omaha]

Your not too  far off. How does it run while this is happening? Any detonation? The simplest thing would be to bump the pressure up to say, 5.5. If this has no effect then maybe the A/F gauge might not be accurate for WOT tuning. Us old timer's used the drag strip or plug reading after a pass. Adjusting the secondary side is not too hard though as it is accessible  from the outside of the carb. Tricks include bending the hanger arms or redrilling the holes in the hangers for the rods. Modifying the rods (chuck them up in a drill and carve them down a bit with a small file and sandpaper). Course you gotta make sure that the supply side is up to snuff. Large lines, needle and seat, float/float level. I like the idea of a return line with the regulator. yes, the secondary plates should only go so far. 90 degrees. or slightly less.

[Cliff Ruggles]

Most likely fuel bowl going low.  Increase the pressure to at least 6psi.  That carb will easily take 6.5 to 7, and see if it improves....Cliff

[74zz430]

Here's what I've done, purchased a .135 needle seat and after disassemble found that Cliff had already installed a .140. Bent the secondary linkage so rear throttle plates only open to about 80 to 85 degrees in line with secondary air baffle, no change. Increased fuel pressure to 6.5 pounds, no change. Decreased secondary valve maximum opening so it only opens to about 80 degrees, this did make a notable improvement my AF it is staying around 13.7 now. But would still like to go a little richer at full throttle.
When Cliff rebuilt this carb, one of the secondary fuel discharge nozzles was bent so he cut both off a little shorter and at an angle. Could this in way way be affecting my AF at wot.

[Cliff Ruggles]

A slight angle cut improves flow from the nozzles and is fine as long as they extend over the divider....Cliff

[74zz430]

The only other thing that I could think of would be a restriction in the secondary transfer passages where the fuel goes down and out of the float bowl and then back up into secondary feed passages. It appears to access these passages I will need to remove the secondary well plugs. Does anyone know the correct diameter for these passages?

[Cliff Ruggles]

There is plenty of room in that area, but it never hurts to pull the plugs and make sure there isn't any varnish, debris of any other obstruction in that area....Cliff