I got my Air Fuel gauge hooked up and at idle it is right at 13.3. I built the car up to 2500 rpm like I do when I launch and it goes to 10.2. Is this normal or does that mean my front jets are to big? In the past I could tell if the jets were to big if when I built the car up it wasn't steady and smooth. I don't notice that at the moment. I'll be at the track tomorrow so I'll see what it does at WOT. 850 carb on a 446 ci. 82 front and 84 rear jets no power valves.

maybe the high speed air bleed is too small.

I haven't hooked up my A/F sensor yet so no tuning experience with it yet, but basically jet for mph and tune accelerator pump squirters and pump cams for 60'. (I got it to help figure out my new Thermoquad combo, but I ran a Holley for a long time.)

A good baseline for a mostly stock cab is the original jetting with 6-10 bigger jets where you removed the power valve. That depends on the PVCR - the holes under the power valve.

You need to lean down both the idle fuel mixture and the transition fuel transfer slot fuel feed size to get it leaner at that lower RPM at part throttle
Do that first before touching the main jets or H.S. bleeds
The H.S. bleeds should only be used to tune the WOT AFR
Idle air bleeds will affect the AFR from idle to WOT also
Good luck, knowledge is power

You might just look down the throat of the carb under those conditions and see if you've got a bunch of fuel coming outta the boosters. If so, tuning on the idle/transition circuitry might not make any difference at all.

I'll have to check that out.

I have a reading of 12.4 at WOT

power valve in the primary? if so it may be opening too soon, you really need to map the afr to find out what it does down track, sounds like your idle isn't terrible but it fattens up with rpm,the csrb I just took off my car did the same thing and found the high speed bleed's were WAYYYY off, and I am running 88 rear and 78 front jetting with a 5.5 PV and it would tank all the way down into the upper9. to lower 10.afr range ,, seriously pig fat but the idle was 13.9 to 14.0.

Want my advice. DONT get hung up on numbers on a gauge. Pay attention to what the car is telling you about what it wants. Then look at the gauge to get a good baseline. There is NO perfect AFR that fits all cars and situations.

I agree, dont worry about what the idle #'s are, every engine is different.

I agree also,,,,to a point, I think afr meters are like dyno's just a tool to get you close and set a baseline, then you can tweek from there, then you can tell what the car want's or don't want,, if you loose your way then you can go back to your baseline setting as long as you write all your info down, I did this to the carb I just built and have every thing in a notebook, now it's time to go out and see what the meter has to say and make my baseline from there,
then start tweeking from that point.

p.s.with the afr meter I found what I thought was a good running carb ended up being a slow pathetic pig and realized that somewhere along the way I had lost sight of what the car wanted.

What size t-slots.........

One further point that often seem to go ignored in a lot of posts. Different fuels have different "target" AFR's. Pump gas(which is a blend and rarely the same season to season, ad any percentage of ethanol and its changed again) is one number, E85(another blend, 9.8-1) another, I use VP fuel and you will find that C10(14.56-1) C12(15.0-1), C25(15.07), Q16(13.6-1), C14+(15.08-1), C45(13.12) etc ALL have a different stioch number based on the fuels characteristics. Just one more reason that there is not and "ideal", one size fits all number. Not to mention things like burn rate, cooling affect, and energy value of a given fuel. Just something that seems to get left out in these conversations.

Each combo will also want different requirements to achieve best ET. Chasing an "ideal" number often is not going to be the quickest ET or best MPH. Also bear on mind when using a single O2 in a collector you are taking an average for the bank which could be biased by one or two cylinders running better or worse than others, air leaks etc. My point is don't go chasing a number thinking ok now my car is as good as its going to get. Pay attention to the old schools things as well, reading plugs, checking timing the things we have always done to tune for the BEST MPH, that will tell you when you are making the best power. Not when a gauge reads 13.7-1. Once you achieve that best MPH then look at the gauge and make note of what you are after. MPH is the ultimate determination of power not a number of a gauge. Hopefully you can have the ability to log as that will help greatly. I see so many people chasing what they believe is an ideal number on a gauge when one, they are not sure what that number should be or two paying attention to the time slip and the car.

Plenty of people here like Dom to help you get the carb tuned to work best for what you want it to do. Just don't forget all the other variables when at the track trying to achieve a goal all for the sake of a number on a gauge. I am sure Dom can lead you in the right direction for what you are after.

One last tidbit for comparisons sake. I work on 3 cars and have two of my own. NONE of them run best at their given fuels STOICH number, none of them. The heads up car runs best MPH and ET at about 1.5 points RICHER than Stoich. The dragster is best at .7 and my car work best at .9 richer. Our fuel curves are pretty flat from .5 to the end of the run on an average, generally within .1-.15 and those numbers listed Just FYI. Oh yeah on 3 of those cars we are reading 8 O2's, one on each cylinder.

Not sure I'll have to check it out when I get off work. It a 850 Proform that hasn't been touch, so should be whatever they are from stock.

Where is your idle spark setting?

That's one thing or sure the total timing people miss the boat. If it's locked out, not an issue.

I was going to post idle timing and that the IFR is probably a bit too big.

A lot of great advice in this thread. Al's is really well written.
I agree with Cab's, and pretty much all the others too.
The question I have for Dusterkid is: How interested are you in tuning? Do you just want to do jets and have fun racing; or is getting into the tuning a little bit more, or a lot more part of your agenda and enjoyment?
Since you are already taking passes at the track, IMO the immediate use of the AFR gage is whether main jet changes cause the expected change in AFR, and whether the AFR stays steady from shift into top gear to end of the track. Under WOT it should flatline. Under other conditions, it can and should be different AFRs. Wideband & AFR
Focus on one aspect and change just one thing at a time.

The t-slots can vary but need to be measured w bits but not just on the metering block face but underneath where the base mounts as they can and will be sized down in that location. Totally agree w/Al in that each fuel has it's burn rates and afr needs and see more power these days leaner like in the 13's and even low 14's than what was considered max power like the 12.5 range. I talked to a VP rep about the 101 unleaded I run and he said just because a fuel is oxygenated doesn't mean it needs richer afr's and my car screams in the 12.8-13.2 zone on the street and plugs look like new but not sure that translates into better et's yet...............Test and test again.............

Timing is locked at 35

Looking to tune it well enough that the car can repeat the number all day long so it makes my life easier when it comes to dialing.

While there's a lot to be said about down-track, WOT tuning and consistency I think the idle/tip-in/acc. pump tuning is very important to consistency. That doesn't necessarily mean that it needs to be perfect or even ideal. There have been occasions when I've been enlisted to do some wideband 02 tuning and the result was traction problems from the newfound power. It's frustrating when things are going in the right direction, ET's dropping and the driver/owner says "no more" just because the car/track can't handle it. Also, no amount of carb tuning can compensate for inconsistent staging or not bringing the exact same car to the starting line each time.

Finally measured the t slots. They are 1/8" in the metering block and are .028" wide at the base

There are no emulsion bleeds installed at all. All 4 of the emulsion bleeds are open.

The t-slot can't be .028 and the emulsions are down in the bottom of
of the existing holes you see..........