Carb tuning

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tresi
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Carb tuning

Post by tresi » Mon Feb 12, 2018 12:37 am

I have many book on Holley carbs but none speak of the air bleeds other than the fact that they are there. What would be some good books that will make me at least somewhat functional at tuning air bleeds?

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Re: Carb tuning

Post by Tuner » Mon Feb 12, 2018 12:48 am


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Re: Carb tuning

Post by turbo2256b » Mon Feb 12, 2018 1:13 pm

funny how the orig HP holley book had more tuning info than the newer editions

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Re: Carb tuning

Post by pamotorman » Mon Feb 12, 2018 1:19 pm

turbo2256b wrote:
Mon Feb 12, 2018 1:13 pm
funny how the orig HP holley book had more tuning info than the newer editions
they have to be careful the feds don't come after them for helping violate the emission standards.

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Re: Carb tuning

Post by MadBill » Mon Feb 12, 2018 5:51 pm

tresi wrote:
Mon Feb 12, 2018 12:37 am
I have many book on Holley carbs but none speak of the air bleeds other than the fact that they are there. What would be some good books that will make me at least somewhat functional at tuning air bleeds?
David Vizard's Holley book has way more to say and charts to show about bleeds (and emulsion tube holes, stagger jetting, etc., etc.) than any of my others.
Felix, qui potuit rerum cognscere causas.

Happy is he who can discover the cause of things.

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Re: Carb tuning

Post by tresi » Mon Feb 12, 2018 11:25 pm

Thanks.
Than you others? Could it be that I have some of your work?

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Re: Carb tuning

Post by MadBill » Tue Feb 13, 2018 12:00 am

tresi wrote:
Mon Feb 12, 2018 11:25 pm
Thanks.
Than you others? Could it be that I have some of your work?
No, I meant than any of the half dozen other Holley books I have purchased over the years.
Felix, qui potuit rerum cognscere causas.

Happy is he who can discover the cause of things.

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Re: Carb tuning

Post by MTENGINES » Tue Feb 13, 2018 1:03 am

tresi wrote:
Mon Feb 12, 2018 12:37 am
I have many book on Holley carbs but none speak of the air bleeds other than the fact that they are there. What would be some good books that will make me at least somewhat functional at tuning air bleeds?
Probably because as society gets dumber, lawsuits go up. So to cover the publisher's butts, they redact any useful information. Because tuning airbleeds and emulsion circuits can ruin an engine. Not saying power valve, main jet timing can't. But it really is best to have someone with a good understanding make those changes.

If you have a basic underswnding of carbs and know how to rebuild one. Just do yourself a favor and trace each circuit, learn how they work and you can come up with the correct assumptions to fine tune them. Otherwise do a search here or on Google. Ask questions. We can help you.

Here is a quickie.
Smaller air bleed makes that circuit respond sooner/richer , larger later/less. S-S, L-L.. you are adjusting how hard the siphon is working by bleeding some off. Or having less bleed off.

Ask any questions you may have and write down in a notebook our responses. Just make sure you make 1 change at a time and log it. Other wise I may suggest pissing in the wind as a hobby.

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Re: Carb tuning

Post by MTENGINES » Tue Feb 13, 2018 1:05 am

As far as books. I would suggest the DV how to super tune and or modify Holley carbs. It's a good reference.

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Re: Carb tuning

Post by tresi » Tue Feb 13, 2018 2:15 am

MTENGINES wrote:
Tue Feb 13, 2018 1:03 am
tresi wrote:
Mon Feb 12, 2018 12:37 am
I have many book on Holley carbs but none speak of the air bleeds other than the fact that they are there. What would be some good books that will make me at least somewhat functional at tuning air bleeds?
Probably because as society gets dumber, lawsuits go up. So to cover the publisher's butts, they redact any useful information. Because tuning airbleeds and emulsion circuits can ruin an engine. Not saying power valve, main jet timing can't. But it really is best to have someone with a good understanding make those changes.

If you have a basic underswnding of carbs and know how to rebuild one. Just do yourself a favor and trace each circuit, learn how they work and you can come up with the correct assumptions to fine tune them. Otherwise do a search here or on Google. Ask questions. We can help you.

Here is a quickie.
Smaller air bleed makes that circuit respond sooner/richer , larger later/less. S-S, L-L.. you are adjusting how hard the siphon is working by bleeding some off. Or having less bleed off.

Ask any questions you may have and write down in a notebook our responses. Just make sure you make 1 change at a time and log it. Other wise I may suggest pissing in the wind as a hobby.
Is .001 one step? Is .005 a lot or a little? I don't have a question about a certain situation. It's just some that I should have an understanding of and I know a little knlowedge can be worse than none.

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Re: Carb tuning

Post by Tuner » Tue Feb 13, 2018 4:59 am

MTENGINES wrote:
Tue Feb 13, 2018 1:03 am
tresi wrote:
Mon Feb 12, 2018 12:37 am
I have many book on Holley carbs but none speak of the air bleeds other than the fact that they are there. What would be some good books that will make me at least somewhat functional at tuning air bleeds?
Probably because as society gets dumber, lawsuits go up. So to cover the publisher's butts, they redact any useful information. Because tuning airbleeds and emulsion circuits can ruin an engine. Not saying power valve, main jet timing can't. But it really is best to have someone with a good understanding make those changes.

If you have a basic underswnding of carbs and know how to rebuild one. Just do yourself a favor and trace each circuit, learn how they work and you can come up with the correct assumptions to fine tune them. Otherwise do a search here or on Google. Ask questions. We can help you.

Here is a quickie.
Smaller air bleed makes that circuit respond sooner/richer , larger later/less. S-S, L-L.. you are adjusting how hard the siphon is working by bleeding some off. Or having less bleed off.

Ask any questions you may have and write down in a notebook our responses. Just make sure you make 1 change at a time and log it. Other wise I may suggest pissing in the wind as a hobby.

Smaller air bleed makes that circuit respond sooner/richer , larger later/less. S-S, L-L.. you are adjusting how hard the siphon is working by bleeding some off. Or having less bleed off.
This just isn't so with Holley type metering. In fact, it is exactly backwards, the opposite is true. I wish you guys would quit repeating this misinformation. You need to read this https://www.tapatalk.com/groups/racingf ... .html#p118

More bleed air from a larger main air bleed (or high speed bleed, whatever you want to call it) pushes more fuel up the main well through the circuit and out the discharge nozzle. A bigger high speed bleed or larger or more E-bleeds makes it richer at the beginning of flow. Depending on other factors, such as size of main well and nozzle relative to venturi and jet size, a larger high speed bleed may or may not lean the WOT high RPM range.

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Re: Carb tuning

Post by MTENGINES » Tue Feb 13, 2018 8:35 am

haha, i had a lot of beer last night.

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Re: Carb tuning

Post by levisnteeshirt » Thu Feb 15, 2018 10:44 pm

I blocked the kill bleeds the other day , common knowledge says this would help response ,, it didn't., , I have found through my own experimenting , it seems there is a window , where they will work as you would imagine , then once you go past the window , it either has no effect or goes the opposite direction ,, ,, if you make a change and it shows no difference, you could be out of the window , best to find where your out ,,, to find gains you have to be making changes that make the predictable result or something is out of balance, ,, then there is high idle vacuum and low ,, I would take what anyone says with a grain and see what works for u

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Re: Carb tuning

Post by tresi » Fri Feb 16, 2018 1:11 am

Thanks, I've read through what you post and ordered some more reading material. i usually have to read things several times to extract all the info. I'm might be facing some surgeries so I'm lining up some reading material for the recovery period.

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Re: Carb tuning

Post by Geoff2 » Fri Feb 16, 2018 4:03 am

What MT said that was correct was that a smaller air bleed starts the the circuit sooner & a larger AB starts the circuit later....& that goes for all carbs, not just Holleys.
And it is drawing a very loooong bow to say that the A/F mixture, once it starts to flow, will always be richer with larger air bleeds; much will depend on the emulsion tube hole positions & their size.

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