When making a jet change to fatten up,when do you change an air bleed VS fuel jet.I'm at 99 square and still lean.Does the high speed air bleed change the entire fuel curve??
The car is finally responding to small changes and I think I'm close to being dialed in

Dominator? What model #?

send the carb to Dwayne or Dons carb with your combination they'll know what to do with the air fuel ratio.

I am by no means a carb tuner, but I will almost always change the bleeds first. One, they are easier, and two I generally like to keep jets in a certain range.

You have the SV1's on there, correct? Well, then throw away everything you know, and give the engine what it wants. And throw away the PS targeted range he prints on his carb sheet as well. Mine is pretty close now, and I am way different than what is on the sheet. I think my air bleeds are off by almost 15 sizes from what it came to me with. Best idling carb and best stable AFR at cruise I have had. My transition is still rich though. I will have to sort port 5 out some more.

Yes, changing the air bleeds ( lo and Hi ) will move the entire fuel curve up and down. If you are trying to address an off idle lean condition, smaller hi speed air bleeds can address it, but you may have to drop jet sizes to keep from being too rich at WOT. Hard to get it all correct throughout the entire engine operating range without a A/F gauge. I have a A/F gauge and still have a hard time keeping the A/F in the range that my set up likes.

Do not overlook fuel pressure and float heights as well. You may be surprised what another pound or so of fuel pressure will change.

Thanks for replies. Yes I have 2 Sv1's and opened the idle air for a cleaner idle and the jets are up to 99's.I have never gotten this far in carb tuning and just ran what it ran.After installing a Racepak and seeing what going on,I have made changes and saw improvments on the next pass.
Last time I was this high in jet numbers was because the carbs were way too small.I can get bigger jets,but thinking smaller high bleed could lower the main jet requirement concidering my jet box only goes to 99.
Thanks to Ralph with SUPER CAR RACES,I've been able to make up to 4 passes in one day to see results right there & then.

I still need lotsa testing,,,,,,,,,,,,,,,,

Yes, both can make a big difference in moving the curve around, and blower motors ( I run a blow through carb - Prosystems carb also ) can make the sorting out process more difficult. Doesn't look like you are running power valves, so you can at least take that out of the equation.

Last passes of the season were all new best for me.I'm within a few degees of the timing sweet spot and with a little more fuel I should be right there. Still need to see when I turn up the boost,if I will need more fuel or,,,,,once they are dialed in they will just feed the elephant.

I might also add that I'm thrilled with the performance of my 3900 lb brick

Holley offers jets up to #110.
I'd keep jetting before swapping air bleeds.

My experience has been that the air bleed is used more when you're looking to change the shape of the fuel curve( or when the jetting is grossly off, which often means its really the wrong carb).
But, they are easy to change and also easily reversible.

Jet until you get fat then back up jet where you feel you get the best performance,then change air bleeds to fine tune what ever circuit need attention.

Can I dial in AFR's on a chassis dyno or is that best left for the track?

You can get it close but nothing simulates actual track testing except for track testing. I would tune it on the street and get it as clean as you can from idle through transition then to wfo then head to the track.

OP, if you get and use a O2 wide ban system use the spark plugs and time sheets for the best MPH in the 1/4, use the wide ban to identify where it is lean or fat Most of the stock type carbs I've used and tuned on a dyno or at the track that had wide bans on them show the carbs. going fatter above 5000 RPM Right where the high speed air bleeds can help Do one change at a time on the fuel bleeds and air bleeds, the idle air bleeds can and will affect the entire RPM range as far as AFR are concerned, not just at idle RPM

This only works if you're in the ballpark w/bleeds to begin with. My 1050 hp came w/71 idle and 37 hi speed bleeds so the idles were close but 37's are WAY too big for hi speeds and thats why I too needed 99 jets to get it better but not right. Now I'm at 70 idle and 28 highs w/82 and 92 jets w/a nice fuel CURVE not just jet it till wfo is good cos anyone can do that........

Critique this if you will. drop box

Critique what?

That is the weird part about the SV1's...They do not always follow conventional thinking with respect to jetting numbers. Mine ended up with #45 hsb's in it and the jetting is around #88... and still jetting down and its way outside the tuning window he gave me and any other carb of that size. Not to mention its on my 605 instead of the 512 it was bought for...I needed street time and AFR to figure it out.

As I said before, keep going, step by step and give the engine what it wants, and forget about what the jet numbers look like. Watch the AFR...

Have you tinkered with ports 1 & 5 much? Just curious. Your the only other person I know that has one of these....Mine is still rich at transition, everywhere else is very close...I think that is port 5 if I recall.

And what did you do to the throttle linkage that made it work? Last I recall, the suction of the blower pulling the throttles closed was an issue.

Have you ever considered just running one SV1 on the blower? I was looking at the G3 Hemi blower options and I would go one carb if I did one...

Click on "drop box".

Cant get in

Hmmm? http://www.dropbox.com/home?preview=FILE0027.MOV

Takes you to a join or login page.

Strange?? When I click on it it takes me right to the video? Maybe because I am already logged in the "drop box"?

Sign in page here too

Was concerned about the lean readings at first but looked good afterwards although I'm not sure what your afr's should be boosted..........

Motor likes between 11 and 12:1. My problem is that it has a tendency to go lean just before the end. Motor is not happy at 13:1 and leaner. I can actually feel it lay down a little just before the line. If I jet up, it is too rich every else. Also have a major lean spot between 1200 and about 2000 rpm ( lean readings you saw ). I'm sneaking up on that area with smaller hi speed air bleeds ( hoping not to make it too rich everywhere else). I usually launch at around 2200rpm. 3500 stall convertor. Wish I knew what I was doing.

[quote=fast68plymouth]Holley offers jets up to #110.
I'd keep jetting before swapping air bleeds.

My experience has been that the air bleed is used more when you're looking to change the shape of the fuel curve( or when the jetting is grossly off, which often means its really the wrong carb).

It's in the high 12's spiking into the 13s wot. So,,,which is better,smaller HSB or larger jet??

The SV1 has a High speed & idle air only. I'm tryin to get a grip on when to make a jet change VS air bleed change.

Pro systems told me to go from .028 to .025 with the HSAB which would be about 3 main jet numbers.

Guess I'll always be a tuner fish,,,,,,,,,,

Starts at the hit of the key,idle was fat so I leaned the idle air bleed and now it's good till I go WOT then it's on the lean side.Plugs come out white with no salt & pepper,heat range looks good. Shutting off at the stripe and looking at plugs also. I figure after dialing it in,I can start skipping the plug read.I always have 5 or 6 plugs on the floor behind my seat,take 4 plugs out to read and throw 4 crappers in for the ride back.

I will check that out,I do have the float level on the low side.

Interesting and good info . The build sheet from pro-systems on my carb (950AN main body) gave me a range on high air and idle air ( high was 33-24 lean-rich and idle was 93-70 ). Think that run was with high = 24 and idle = 70 - both on the max rich side per their build sheet. No range given for the main jetting, so I assume they just want me to fine adjust with the air bleeds . I know we have vastly different set ups, but curious how your build sheet for your carbs reads and if 3 HSAB size change equates to 3 main jet size changes in all cases. Don't mean to hi-jack your post. Trying to learn also.

The thing to understand most manufactures will give you a range to work with and Holley tell leave it where it is OTB.The truth be told this is good advice but Holley and most manufactures don't know your combo and the condition of your engine and your as run or as raced track,weather and all the other conditions that cause changes like altitude and air density.This makes your jetting and adjustments unique to your conditions and your combo.I find many that disagree with my methods but it usually works for me,if I become to confused with carburation calibration I can alway swallow my pride and ask AJ Casini.

It's been a long learning curve for me as I can't get to the track as often as I would like.Installed new wires,distributor & coil to finally figure out the Holley Pro Strip Annialator was bad after 15 years of service.After I installed a 6al-2 at Bill Atwoods rec,the car ran better than it EVER did with the blower motor.

Somebody on this post mentioned changing emulsion tube jetting ( top jet to smaller size )to fix my off idle lean spot. Can't find that thread?

I had posted suggested bringing the top emulsion hole down in size. But I deleted it thinking that the post had turned more to tuning the SV-1.

Any emulsion holes ABOVE the fuel level in the bowls will affect the transition from the idle circuit to the mains. Assuming that the mains are not coming in too late, then I would try putting in a .010" to .015" wire in the top emulsion holes and see how it likes it.

You could also try sizing down the next lower emulsion hole if the engine likes the top hole restricted.

I know that Thumperdart doesn't like the wire test. But it is quick, easy, and effective. And they can't go anywhere so they are a safe test.

Another thing to check is the feed hole for the transition slot. Make sure it is large enough. But I see more issues with too large of a the top emulsion hole than I do with undersized transition slot feed holes.

Thank you Dave. Gonna give that a shot.

Keep us posted.

Pulled the carb apart today. the 4 emulsion holes are the same for both pri. and sec. sides. #1 (top hole) is .029",#2 hole is plugged, #3 hole = .026", and #4 ( bottom hole) is .091". All holes are below the recommended float level. Since they are all below the fuel level in the bowls, I don't think making the top hole smaller is going in the right direction to cure my off idle lean condition I'm looking at opening up the second ( plugged hole) to some size ??? Your thoughts? Remember, this is a blow through carb.

This is just a guess and is not based on any experience, but why not try opening up the second hole since it is below the fuel level and see how the engine likes it. You can always plug it back if the engine doesn't respond well.

And you may consider experimenting with the top hole as well once you get a sense of how the second hole affects things. As long as you do one thing at a time and keep track of what you do, you can always put it back the way it was.

Think that's what I'm gonna try.

I'm also thinking that back pressure is diluting the combustion chamber causing it to go lean,,,,,,,,,,,

If there were enough back pressure just off idle to significantly impact the fuel mixture, what would be happening at WOT?

IF it had that much back pressure it would do 1 of
2 things at higher rpm.. 1.. it would blow the exhaust
off the car(at any one of the joints).. or 2.. it wouldnt
make the rpm... its making some rpm (I dont know how many
rpm he is turning) so at idle/just off idle he shouldnt
see any issues at those rpms... he HAS to put a gauge on
it to see what his back pressure TRULY IS and work from
there.. when I was testing all sorts of exhaust I did see
a system blow the pipe off during a test.. needless to say
we didnt use that system.... the nice little inward roll on
the exhaust tip(on the chrome tips) was a 3hp loss with just
that inward roll on the tip(thats back pressure due to flow
loss).. most people would never think that would be a issue
EDIT
to check the idea of the mixture going lean.. one way
to test that.. pull the exhaust off(open it) and run
it with a A/F meter... On my Rampage I went with elec
dumps just so I didnt pull the exhaust but yet reduce
the back pressure

My question was really meant to be rhetorical.

And I also went with electric cut-outs because getting a relatively quiet exhaust to flow my 500" engine kept getting more and more complicated and more and more expensive. And frankly, the only way to truly know what combo was going to work, was to install it and test at the track back to back. But that would require buying a lot of pipes and mufflers besides being a bunch of work.

The Doug's cut-outs are sure-fire at the track and are a lot of fun at shows and cruises. Plus, I get to listen to the radio and/or talk to my passenger while driving down the road.

I would suggest swapping the top and second emulsion holes, plug the top, .029 in the 2nd. And are you sure about the .091 bottom? I would try plugging it, way too large.

Ok, First, the run I posted is with open headers ( no back pressure on the exhaust side). On the carb side, the dump valve ( anti-surge valve ) remains open (Dumps air to atmosphere )until the manifold goes in to pressure - so my lean condition ( about 1200 to 2000 rpm )occurs while the manifold is still under vacuum. Even doing a burnout ( see posted run ) the engine is still under vacuum. The minute I floor it, vacuum drops to 0, dump valve closes, and manifold goes in to pressure - and lean condition goes away. Yes, I am sure about the emulsion sizes I previously posted. So, I went ahead and drilled out the 2nd emulsion hole ( previously plugged ) to .026". Four holes ( top to bottom ) are now .029, .026, .026, and .091. Just ran the car that way. Virtually no change. Lean spot is still there. A/F reading at idle might have gone a little richer ( 12.0:1 to 11.5:1 ). Still open for other suggestions. FYI, shifting at 7K. Will probably go back to how it was and try something else.

Talked with Patrick over at ProSystems yesterday. They are my original carb builder. He wants me to pull out the primary side PV and plug it (sec side is plugged) and jet up to the sec side jet size. I will give this a try next.