rich carb
 

holley carb go fat at start and low gear in high gear is is about 12.7
need help

Re: rich carb
 

Using a power valve in primary side?

Re: rich carb
 

Dripping Bosters?

Re: rich carb
 

yes power valve no dripping

Re: rich carb
 

Vic
I’d be looking real hard at the idle circuit.
If your going off a 2-step, wot, it will be rich.
Footbraking you might play around with squirter size, most Holleys are around a 28 Stock I have run as high as a 43.
How fat is it down low ?

RJ

Re: rich carb
 

10.6 afr

Re: rich carb
 

If your O2 is in your collector, and it is within 12” from the end, you will not get a “clear” read, it will always show rich until you bring up rpms as in making a pass down the track then it will read correctly.
You can slip on an 18” extension to the end of collector and tune it for lower rpms (2 step leave or foot brake leave). Then take off extension. It’s is sucking air back up past the O2 sensor and it will show rich until you get rpms up and going down track.

Good luck
RJ

Re: rich carb
 

Actually it'll show lean.

Re: rich carb
 

Put O2 sensor in primary pipe.

Re: rich carb
 

In my experience on a carb combo it showed rich when staging with 2 step at 3000 rpms or so. Moving O2 or extending collector will correct that.

On an efi combo putting an extension on allowed us to tune it so it did not search and go lean/rich while in 2 step staging. Like the computer couldn’t make up its mind up from due to O2 not getting clean data. That was with a BS3 system but believe it to be the same with all.

Believe Vic’s combo is 780 Holley but maybe not.

RJ

Re: rich carb
 

2 step = rich reading

Re: rich carb
 

If it was me I would take out the power valve, plug it and go up 4 jet sizes in the primary. Then evaluate.

Re: rich carb
 

Cams like we run often causes low enough manifold vacuum to open the power valve at idle. The number on the power valve tells you at what point in manifold vacuum dropping as load goes up, it opens. If it says 85, the power valve opens, and adds fuel at 8.5” of manifold vacuum. A “45” will stay closed, and leaner, above 4.5” of manifold vacuum.

When I had my old IHRA Super Mod Camaro, it had the standard 750 cfm Holley we had to run in NHRA. Was a tad faster than an 850 on that 292”. Before I figured out the “High Speed Air Bleeds”, it was going lean at high RPM. I put a vacuum gauge on it to see if it was pulling vacuum “up there”, it was pulling 3” of vacuum in the lights. I went to a “25” Power Valve, and picked up a MPH. Bigger high speed air bleeds was a tad quicker.