Air Bleeds

[River Rat 005]

I've got a 1050 HP. Thinking of playing with the air bleeds to get better throttle response. Question is, will the weather affect these jets the same as it does on the main jets, or will they be set until I change my combination?

[Sleeper CP]

I believe air bleeds are for ultra fine tuning. They are more sensetive than jets and will be more affected by temp.
Two of the carb guys I use have said " your need to run air bleeds so you can fine tune that thing" Excuse me when I go out in the morning it's 80 and at 2pm its 110. Exactly how many times do you want me to adjust my carb in one day. I haven't worried about just for that reason.
If you are at the track it might make a difference, but for the river I wouldn't worry about it.
Sleeper CP

[TIMINATOR]

True story. Air bleeds primarily affect upper rpm jetting, a smaller bleed will progressively RICHEN the mixture as the rpm climbs. Typically of little value to the TYPICAL LAKE boater. Except with a blower. TIMINATOR

[BDMar]

It depends whether you have a two or three circuit dominator. The three circuit (0-8896-1) has an idle, intermediate, and high speed air bleeds. They each control the area listed, not top end only. The intermediate is usualy the only one you'll mess with. Going a little larger will help get rid of that low-midrange richness.
If you have the two circuit (0-8082-1) and this is a pleasure boat, you will be able to get it very close with just jets.
Throttle response is mostly controlled with the accelerator pump cam and nozzel size.

[cyclone]

think of the air bleed as a controlled air leak. small changes in orifice diameter will yield larger changes in a/f than a jet change. its real easy to screw up your carb by changing the air bleeds without some way of monitoring a/f while the engine is runnign under load.
best left this tuning area to a carb expert.

[Gearhead]

Cyclone and BDmar are correct.
Be very careful when working with a high speed air bleed. This is the most sensitive circuit in the carb. The high speed AB should be changed in .001 increments. The carb/engine is very sensitive to hsab changes and this is where you can get into trouble the quickest. Difficult to tune without a/f instruments, clocks, dyno and pyrometers.
The intermediate can be used for just that. Intermediate fuel changes. This circuit comes in just off idle and can be tuned to assist acceleration. Again, it is hard to tune the intermediate ab without clocks, dyno or a/f info.
The idle air bleed is the easiest to work with. On the idle air bleed. First set your mixture screws for a decent idle and good throttle response. Then check to see how many turns your screws are out. If they are less than one turn out, go up on the idle air bleed a few thousands and check again. If they are more than 1 1/2 to 2 turns out, then go down on the idle air bleed a few thousanths. Generally you wan the engine to idle decent and have good throttle response at the 1 1/2 turn (3 flats) out. Of course pump shot and intermediate come into play on the response with a three circuit. If you cannot tune the idle with a few step changes in the air bleed, then it is time to resize the idle fuel jet or orifice. This actually comes into play with ALL the circuits as you are balancing fuel and air needs for the engine requirements.
Again it is best left to a sharp carb tuner. Always remember where you started from so you can put everything back the way you found it if you goof it up

[Sleeper CP]

Gearhead,
Thanks for the extra info. In the end do you think he should fool with them or not for his better throttle responce? I did that with squirters and accel. pump.
Sleeper CP

[Gearhead]

Hmm... Sleeper.... now you are putting it on me! If we are woking with acceleration and transition, I think I would check the idle circuit first to see if the mixture screws were in range. Then I would work within reason on the squirters and pump adjustment. The squirters generally should not need sizing more than .005 to .008 thousanths. Don't overdue it.
If it is not working well now, then work with the intermediate. Generally the intermediates come in quick and are on the fat side, but some large plenum intakes require a lot of fuel to get any lean spots out on takeoff. As per earlier discussion the air bleeds do adjust mixtures, but also affect timing in the circuit. In other words a smaller bleed will quicken a circuit as well as making it richer and converse the larger bleed will lean or slow down the timing of the circuit. It is a pretty good balancing act! For acceleration you will be primarily working with the idle, acclerator pump and intermediate on a three circuit carb and the idle and accelerator pump on a two circuit.
Mainly the main circuit is for your wot, the area that you spend the most time and a slight adjustment may be needed depending on application.
Again.... rmember where you started from just in case all gets worse
I hope this helps a little. There is not a short simple answer when balancing circuits. You don't want it rich... but you sure don't want a lean stumble! Error to the rich is generally much safer and an initial quicker accleration to the point of blubbering and blowing black smoke out the pipes.