WOT AFR and secondary rods

[bluesmobile]

Hi there,
Thanks for your expertise Cliff!  With the help of your book and PY forums, I have some really good-running Quadrajet-powered cars! 

I do have a question on one of my combo's, I need a little reality check from you guys before I go running off in one direction...
I have a 1972 Grand Prix with a 10:1 CR P400, HR cam 230/236@0.050, runs really well up to 5500 RPM (that's where I set rev limiter for now).   The Recipe #3 Edelbrock #1904 quadrajet has secondary rods from Cliff's store, the DA rods (0.044 tip) with a G hanger.  It's fed by a Carter mechanical pump and is set up for road course duty.  I had it on track last week for a testing session, and it runs really well in all conditions: accelerating, braking, cornering (1.2 g's on the carousel according to my data acquisition).  I have the luxury of an Innovate wide-band AFR meter, and it was showing a steady 10.5 AFR when at WOT down the straights at 3500-5500 RPM.   I use pump gas, 93 octane.  I swapped back to my original Edelbrock DR rods (leaner than DA but I forgot the actual measurement) and used the same G hanger, and AFR moved leaner to a steady 11.5.
I'm contemplating buying 2 set of rods for testing: CK (0.0527) and AY (0.0567) to lean out the WOT a little more, and target 12.5 AFR.    Am I on the right track, or is there something else tunable?
I'm asking the questions since it is noted that the DA rods are "For all combinations".  Is there something else I should be looking at besides secondary metering rods to get a leaner WOT AFR?

Thanks!
Jeremy

[novadude]

If I remember right, DR rods are a .0567 medium power tip.

I don't know why, but any of the carbs I've built have all seemed to like the .0527-.0567 rods and not the richer 0.044 rods Cliff seems to recommend.  Maybe it's because I am usually messing with smaller engines (327-396 ci range).

[bluesmobile]

If I remember right, DR rods are a .0567 medium power tip.

I don't know why, but any of the carbs I've built have all seemed to like the .0527-.0567 rods and not the richer 0.044 rods Cliff seems to recommend.  Maybe it's because I am usually messing with smaller engines (327-396 ci range).

Thank you for the confirmation on using the leaner secondary rods, it helps my confidence in what I'm doing.

I just revisited the specs and the DR rods are 0.0569" power tip, you are right.   This is leaner than I remembered.

I guess I will have to go with a lower hanger to get leaner than the DR rods, as there are not many other rod options out there, except the CL rods, which go all the way to 0.0667" tip, and is probably too lean for race track duty cycles.

What AFR would you guys suggest targeting?   My engine has decent internals, forged rods and ICON pistons, #62 heads.   36 degrees total timing, 10:1 SCR, no hint of spark knock on 93 pump gas.

Jeremy

[Cliff Ruggles]

Most engines are fine with 12 to 12.5 to 1 or so at WOT.  There may be a few HP hiding in there someplace by going leaner, but the EGT's take a sharp rise and you reach a point where detonation becomes a possibility when going really lean.  It's is ALWAYS better to run a tad rich and the engine really doesn't loose all that much power, plus EGT's are lower and much less chance of putting a piston in the oil pan!.....Cliff