Last year I finally started to fine tune.Started jetting up with plug readings using the azz dyno and time slips.Only getting 4 runs in a day made it a loooooong process.I ended the season with the biggest jets I have which are 99's and its square and still a little lean.My carb guy said to start reducing the air bleed size.
What I would like to know,what is the difference between increasing the jet size VS reducing the air bleed. I can see where I might be able to make small changes due to the DA with air bleeds only.Is that ok,,or should I be making those changes with jeta??

I use the ratio of 1 bleed size = 2 jet sizes..
its close but not perfect.. so if you want to
drop 10 jet sizes you drop 5 bleed sizes

Depends on how efficient the carbs are but we have usually seen closer to one bleed being more in line with moving the jet 3-4 sizes. But your results may vary. My opinion would be don't get to carried away with dropping the hi speed bleed, and we are talking just replacing the high speed bleed here. They also sell larger jets than 99, and not all jets are created equal. You could buy 100, 102, 104, 106, 108 and 110's. But honestly buying a Holley jet and not pinning it who knows

Not uncommon to have jets that are way bigger than needed if the hi speed bleeds are too big and I too was at 99`s w/ .037 hi speed bleeds so I went w/.028 hi`s and brought the jetting down to 84-92 (ft. p/v) and now it rocks. What size are the hi`s now...........Another note; can`t pin holley jets w/any accuracy due to the taper unlike others like maxi jets and maybe BLP which are numbered to size not flow...........

Guess I should ad changing two that pin the same will do little to change the curve. Yes some do have different taper that Holley claims this changes the amount of fuel it flows but it will do little to change the amount of fuel there. Funny how no one else does this, so makes one question how much this taper changes anything. I hear the no use pinning thing all the time, I have pinned every Holley jet from 62-110 and can tell you the only time I have seen the same pin size is in SOME sequentially numbered jets, Most likely why many suggest never bothering to change just one sizes at a time, always go up 2.

I think after a 70 holley jet the hole gets bigger BUT the taper and depth changes therefore the FLOW changes. No bs just facts and holley is all I use and the small changes react as they should...........one holley jet equals roughly a 4% change in flow and if it wasn`t for the holley engineers 50 years ago, none of these other holley "copies" would exist.........

Air bleeds (or correctors) are more about the fuel curve than whether the mixture is rich or not. I wouldn't mess with the bleeds unless you have a pretty good idea that your fuel curve shape needs to be adjusted.

We prefer jets where the numbers actually MEAN something Cannat say I have seen the same results on the dyno going up one size on many holley jets. But all I have to rely on is my experience on the dyno reading AFR numbers and jets. I am not a carb guru for sure.

BTW it if was not for Henry Ford we would not be where we are either. Things progress you either keep up or fall behind. To each their own. Guess we should just keep using those old sand cast metering blocks and porous main body and boosters too

I`ll keep that in mind Andy after the many I`ve fixed w/(don`t touch the bleeds)are awesome just ask around and yes the bleeds are the curve and when the jets are out in left field the CURVE is jacked due sometimes to hi speed bleeds. Again Andy, you spend time in a dyno room(not real world)and I test/tune on the mean streets and most on here are faster and cleaner after I touch the "don`t touch" hi speed bleeds. Al, I usually see results from a two jet or more change and I love the billet pieces and modern touches for sure it`s just the WACKED tunes as YOU`VE admitted that needs help........Forgot; I have two local 8-second street/strip cars that have stock blocks n bowls on em SO they do work just not as light and pretty.......

As the RPM and the boost goes up,so do the AFR's.I'm stll pulling plugs,so easy with a hemi.It's getting into the high 13's with NO speckling.I'm starting to thing that back pressure might be diluting the combustion chamber
At this point I can see the results on the next pass,unfortuatly I have to wait 'till spring to continue being a tuna fish.My next 2 obsticles will be heat & the full exhaust.

The air bleeds, high speed and idle affect the mixing of air and fuel in the carb. I look at the percentage of difference in hole sizes when changing the bleeds, a .027 bleed compared to a .029 bleed is substantial difference in the percentage of the hole sizes. Bigger bleed hole equals more air with less fuel, less hole size equals less air amd more fuel into that circuit The idle circuit bleeds affects the air fuel ratio from idle to W.O.T no mattr wah the RPM I remember a statement in National Dragster that the Pro Stock teams didn't change jets in thier carbs. once they had them dialed in from Denver in the summer to Pomona in the winter, they would and did change the bleeds for each track and weather conditions on a regular basis
Tune off the spark plug and time slip for that day, unless you buy and use a wide ban Once you get the car as good as you can from jetting then try tuning the bleeds IHTHs

AGAIN, What size hi speeds bleeds are in it(em)now...........

Dom,they have .038 in the high bleeds,jets 99 square.Best pass so far had 30* timing.Want to try 28* and see if it picks up.I will change the HSB's and start from there in the spring.
I did install a Racepak logger dash so I can see what's going on.Want to find the limit on pump gas with a few more passes,then overdrive it then see where it will go.At almost 4k LBS,it's a handfull

Are you by chance using E-vacs with them ahead of
the O2 bung.. if so.. change that.. you will get a
bogus A/F reading... also if the bung is near the
exit of the collector.. that will give you a lean
number also

I have never liked how Holley jets are not the same size as the number once you get above a certain size which is around the 80 or so size. I always measure the Holley jets with my drill sizes. Sometime you can go up a number or two and not even change the jet size if you forget that they dont always match the number on them. Ron

Try some 28`s for starters and watch what happens w/the jetting........

So at this point it doesn't matter which way to fatten,be it bleeds or jets??

What do you have for a jetting set... if yours goes
up to 99s now then yes it would matter.. unless you
want to start buying more jets.. I have 2 sets(boxes)
that range from 35(I think) to 99.. I have 2 sets for
when I was running dual 4bbl and when I got my dom
from QF after having them set it up for E-85 I asked
if they could set it up for the jets I have.. they did
so that way I wouldnt have to go buy more.. just something
to think about

That's what I was unsure of.If one changed the AFR differently than the other my jet selection ends at 99.I want to fatten the bleed and take some jet out.Then see how it effects my AFR's.I also put an air temp sensor in the intake to see what the temp is when I hit the heat ceiling.I also wonder how back pressure effects the AFR's.

Evac is capped.O2 should be back far enough in the exhsust pipe.
Collector is 4 inch going into 4inch exhaust reduced to 3.5 In front of the muff When I remove the exhaust,I will need extensions and put an o/2 bung in them.
I Thoght bleeds & jet changes effected the AFR differently