Holley 4150 tuning
#1
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I have a Holley 9022 800 CFM carb on a 439 cid BBC...
When the secondaries start to open it goes RICH.....
I have 75 jets in the primaries and 86 in the secondaries...(no secondary power valve)
A/F ratio on just the primaries is 12.8:1 cruising at 3000 RPM.
A/F ratio is 12.5:1 at full throttle.4800 rpm (prop is a bit too big)
At 4000 RPM, when the secondaries are just partially open, the A/F ratio is 10.5:1... Any way I can tune this out ?
THANKS !
Doug
When the secondaries start to open it goes RICH.....
I have 75 jets in the primaries and 86 in the secondaries...(no secondary power valve)
A/F ratio on just the primaries is 12.8:1 cruising at 3000 RPM.
A/F ratio is 12.5:1 at full throttle.4800 rpm (prop is a bit too big)
At 4000 RPM, when the secondaries are just partially open, the A/F ratio is 10.5:1... Any way I can tune this out ?
THANKS !
Doug
#2
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yes.install a power valve with a lower number so it does not open as soon.
Last edited by mike tkach; 07-21-2015 at 07:44 AM.
#4
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Very possible ^^^what he said^^^^ - this can be determined by using a vacuum gauge in accordance with the wideband A/F set up.
It could also be:
Is this exactly when the secondaries are starting to open ? If you leave throttle there for a few seconds or more, does the A/F ratio come back up a little ?
Reason for asking is that since this is a DP, the secondaries have a accelerator pump also. As you know, the pump shot starts right as it's throttles are being opened.
It could also be:
Is this exactly when the secondaries are starting to open ? If you leave throttle there for a few seconds or more, does the A/F ratio come back up a little ?
Reason for asking is that since this is a DP, the secondaries have a accelerator pump also. As you know, the pump shot starts right as it's throttles are being opened.
#5
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#7
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Very possible ^^^what he said^^^^ - this can be determined by using a vacuum gauge in accordance with the wideband A/F set up.
Is this exactly when the secondaries are starting to open ? If you leave throttle there for a few seconds or more, does the A/F ratio come back up a little ?
.
Is this exactly when the secondaries are starting to open ? If you leave throttle there for a few seconds or more, does the A/F ratio come back up a little ?
.
#8
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Don't estimate. Put a gopro over it or mark your hand throttle level where sec are just starting to crack open.
#9
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I was estimating the amount of secondary opening at 4000 rpm....
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#10
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Sounds like you need to go with a smaller secondary air bleed and jet. If I am recalling correctly air bleeds tend to add a greater percentage of air with increased cfm. So the Air bleed is giving you a rich to leaner condition as air flow increase through the carb. You need to size the air bleed so AR is constant then jet accordingly.