46M primary metering rods

[Matte]

Hey Ladies and Gents,
From what I've found the M series rods only go down to 48M, however this does not give me enough APT control.
Is there anywhere that makes 46M or smaller rods for the aftermarket?

Even with the 0.036" tips of the M series rod, WOT is too rich with 72 jets and too lean on part throttle.
The carb is a SMAB built to the specifications in Cliff's book.

What other options are there? Reduce the main air bleed? Increase idle jets or down channel restrictions?

Smaller rods would really be the best option if possible.

Cheers,
Matte

[Cliff Ruggles]

Tune the primary side separate from the secondary side.  Tune for jet size first, by doing some heavy part throttle driving without the secondaries.  Once you have found the ideal jet size, tune with the primary rods and APT.

WOT tuning is done last, by changing metering rods and hangers....Cliff

[Matte]

Hi Cliff, and thanks for your swift response!

I should have left a more detailed original post. I am a long time viewer of these forums and this is my second quadrajet build based on knowledge gained from your book, here and various other things I have picked up over the years.

I have been testing this particular carby extensively in much the same manner as I usually do.
I have a wideband air fuel gauge combined with initially using the choke lock off to prevent the secondary throttle butterflies opening so I can fine tune the primaries.

With this in mind, I currently have 72 jets combined with 0.036" tips of M series rods giving me afr of between 10.8:1 and 11.2:1 at WOT. It would be ideal to put in smaller jets, which I have from a previous purchase from you, however with the APT screwed right up giving me no movement from the 52M rods I am getting 15:1 afr and higher.

From your past comments in other threads, I assume the 52M rods taper down to 0.042" before stepping down to 0.036". If I use your supplied 44 rods, I can get good light throttle and cruise afrs with horribly rich WOT based on the 0.026" tip.

Ideally 46M rods would taper from 0.046" down to 0.036" while still giving me some adjustability with the APT.

I assume also that there are alternate ways to achieve this so will try adjusting the idle down channels and idle tubes to be larger hoping to add more fuel throughout the range, though it doesn't seem to be necessary from what I have found in your other quoted recipes.

Would a smaller main airbleed have a better effect? This would obviously be harder to make smaller than to make the idle channels and tubes larger, but I will do so if preferred.

I appreciate your time.
Regards,
Matte

[Cliff Ruggles]

What is the carburetor number and size of the MAB's?

There are other players at work here, fuel pressure, float setting, size of the fuel inlet seat.  What are those specifications?

It's actually pretty easy to tune the SMAB carburetors and most easily fall into range with the "M" series metering rods. 

To use K, L, or P rods you have to reduce set size a few numbers, and may need to open up the MAB's slightly.

I would also mention that the primary side NEVER sees full throttle without the secondaries, so tune it for best overall fuel economy and power up to about 2/3rds throttle position, and fine tune full throttle A/F with the secondary metering rods......Cliff