Center cylinders lean question.

I am have a lean condition on the center 4 cylinders with a C460 manifold and C460 heads. the carb is a Gen 3 Holley 1425 CFM with 2.375" throttle bores. I am just wondering if other have had a similar issues and possible solutions for this. A different carb or manifold work? Any help would be great.
Thanks in advance for all of the information.

Michael Remines

I don't have an answer for you but was wondering if you have a carb spacer and if so which one?

Also, any port work on the intake?

Thanks, Sheldon G

Yes the manifold has a good bit of porting done to it. Yes I am running a 1" open spacer not tapered just straight.

Michael Remines

Are they lean, according to what the plugs look like?....or are you using individual cylinder 02 sensors?

I have the heads off and there is a big difference in the the center 4 as to the coners. You see it in camber and the cylinders.
Michael Remines

I’ve seen cylinder to cylinder issues on mine, if you have room try a stacking a few spacers

Turn the carb sideways; especially if it uses a cable linkage.

It may not have anything to do with a fuel distribution issue but I helped a guy on a bbc with a new gen3 Holley. Nothing we did would put enough fuel in the engine. Belt drive pump checked ok, air bleeds swapped with no affect. Finally sent to BLP for an extreme makeover to find out the metering block passages were too small. I recall them having that same problem years ago on another dominator carb. BLP metering blocks and it was a whole new animal!

I spoke with my carburetor guy. We talked back and forth a few time and I sent him manifold plenum area pics. He feels there is something going on in the carburetor. i think i will look at this for now and see where it leads. I will let every one know what we find from here once engine is back together.
Thanks for the information and suggestions,
Michael Remines