Holley 4150 tuning
07-21-2015, 07:29 AM
#1
Holley 4150 tuning
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
07-21-2015, 07:42 AM
#4
Registered
iTrader: (1)
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.
07-21-2015, 07:44 AM
#6
Registered
iTrader: (1)
07-21-2015, 10:32 AM
#7
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 ?
.
07-21-2015, 11:20 AM
#8
Registered
iTrader: (1)
Don't estimate. Put a gopro over it or mark your hand throttle level where sec are just starting to crack open.
07-21-2015, 03:32 PM
#10
Registered
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.
