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

yes.install a power valve with a lower number so it does not open as soon.

would you want a lower number?

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.

yes,i just woke up so not thinking yet.i will fix my post.

You need a Java Shot, not a Pump Shot. LOL.

It stays constant at 10.5:1 while cruising.. I would estimate that the secandaries are open about 1/4 of the way at this point...

Don't estimate. Put a gopro over it or mark your hand throttle level where sec are just starting to crack open.

I had the hatch off and was watching it.. 3000 RPM is definitely when the secondaries just start to open...

I was estimating the amount of secondary opening at 4000 rpm.... :)

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.