is it ok to mix and match metering rods

[MRSOFTE]

Running a 7043213 on a bone stock original 1973 Z-28. 74/48 and Cliffs black spring combination. Engine at idle only shows 12.5 inches with an A/F of 14.7 or so. I threw all that in, in case its relevant. Oh, I'm at 4600 ft elevation.

At cruise 35 MPH the A/F is approx 14.7-15.6 at 60MPH 15.5-16.3. Finally, my question, are these A/F's ok? If not can rods be mixed to achieve a different overall A/F?

[77cruiser]

How does it run?

[70GS455]

Running a 7043213 on a bone stock original 1973 Z-28. 74/48 and Cliffs black spring combination. Engine at idle only shows 12.5 inches with an A/F of 14.7 or so. I threw all that in, in case its relevant. Oh, I'm at 4600 ft elevation.

At cruise 35 MPH the A/F is approx 14.7-15.6 at 60MPH 15.5-16.3. Finally, my question, are these A/F's ok? If not can rods be mixed to achieve a different overall A/F?

Yes, those are fine. What are AFRs at WOT?

[77cruiser]

Is the idle stinky with it that lean? Mine gets stinky at idle when it lean.

[MRSOFTE]

14.7 into low 15 zzzzz at idle no real stink. Now with 44 rods, oh my gosh burning the eyes at idle. But at that same time I had cliffs blue power spring in. So this engine as I said only pulls 12.5 Hg. So maybe the blue spring wasn't my best idea.
WOT is ok at 12's.
Black spring and 46's and I believe I saw cruise at 12's maybe low 13.  So jumped right to 48's.

Starts and runs real nice but just maybe I feel a surge on occasion? I do see my AFR gauge slip into high 16 and maybe low 17 once in a while. I also know that not all cylinders will see the same thing.

This is why I ask is it permissible to keep one 48 in and go 46 with the other. Is that a silly idea? Ha!

[lightning boy]

You can try a richer rod no problem. Bit be careful chasing afr numbers. If you see and improvement good deal. If not go back to the old ones. If it is lean at part throttle it will buck and surge. Give the motor what it wants, don't trust the afr.

[MRSOFTE]

Was just out driving with no surging at cruise as far as I can tell. Nothing jumps out at me no pinging leaning into it, feels good, and I bumped up the timing 5 more degrees to 32 total all in by 2500.  That made the throttle a little crispier.

I will put in one 46 rod today just to richen the cruise a tad.

[77cruiser]

I'd go up more on the timing.

[Kenth]

Factory jetting for 7043213 is #74 jets and 44B primary rods. DA secondary rods and 7036019 8 - 4 in/hg power piston spring.

Burning the eyes at idle indicates a too lean idle circuit, has very little if anything to do with the power piston spring.
With todays fuels the only thing i would do in your carb is opening the idle/low speed jets (tubes) to about .039"-.040" for a proper combustible mixture.

Remember the engine is running on the idle/lowspeed circuit up to about 35-40 mph before the main circuit/jetting complements the mixture, and at that (engine) speed the factory jetting is adequat.

And, with a properly set up/modified carburetor there is seldom, if ever, a need for a modified ignition curve.

HTH