Secondaries rich momentarily

[jxu109]

68 c10 super T-10 3:73 posi,
350 Performer RPM intake and heads, Comp 270H cam
I have a late model 800 CFM Q-jet using recipe #3.
76 Jets 54M rods - Primary side is probably about as good as I can get it.  I've been messing with it for at least 6 months, and I don't think anything needs to be changed there. At half throttle or so in second and third gear, My AFR is in the mid 12's, and I'm seeing cruise AFR's in the high 15's/low 16's...

Choke pull off is about 2 seconds, secondary spring is at 1/2 turn, using CH rods with a short tip.

When the secondaries open, MY AFR goes into the mid-10's, and as it revs higher, the AFR will creep up to about 13.4 --

Is this about as good as I can expect?  I don't really feel a bog or anything, so maybe it's good as-is.  I'll be at the track in 2 weeks, so I'll be able to do a full throttle 1st-4th gear run to see how the secondaries hold up over a long stretch.

The only thing I can think of doing is making the secondary POE outlets a bit smaller, but I'm not convinced it well do much for performance if anything...


Thanks-

[Cliff Ruggles]

Even though it may not be a problem, several things can cause this. 

Flaps opening too slow, and for just an instant this pulls more fuel from the main nozzles as they come on line.

Metering rods too high, lower them slightly and see if there is an improvment.

Too much pump shot from the accellerator pump.  You only need enough to avoid a lean condition, too much will show a rich condition momentarily.

The reason I said it may not be a problem, is that if you don't put in quite a bit of fuel as the huger secondaries come on line, it may stumble/hesitate or "bog". 

I quick test is to move the pump link to the outer hole on the lever.  This will reduce fuel during transition.......Cliff

[jxu109]

I already have my acc. pump on the outside.  I'm wondering if the wrong pump isn't in there.  I've been meaning to change it out, but I'll also try changing spring wind up to 1/4 turn...

I'll call tomorrow about the ACC pump.