Pulled the carb apart today. the 4 emulsion holes are the same for both pri. and sec. sides. #1 (top hole) is .029",#2 hole is plugged, #3 hole = .026", and #4 ( bottom hole) is .091". All holes are below the recommended float level. Since they are all below the fuel level in the bowls, I don't think making the top hole smaller is going in the right direction to cure my off idle lean condition I'm looking at opening up the second ( plugged hole) to some size ??? Your thoughts? Remember, this is a blow through carb.

This is just a guess and is not based on any experience, but why not try opening up the second hole since it is below the fuel level and see how the engine likes it. You can always plug it back if the engine doesn't respond well.

And you may consider experimenting with the top hole as well once you get a sense of how the second hole affects things. As long as you do one thing at a time and keep track of what you do, you can always put it back the way it was.

Think that's what I'm gonna try.

I'm also thinking that back pressure is diluting the combustion chamber causing it to go lean,,,,,,,,,,,

If there were enough back pressure just off idle to significantly impact the fuel mixture, what would be happening at WOT?

IF it had that much back pressure it would do 1 of
2 things at higher rpm.. 1.. it would blow the exhaust
off the car(at any one of the joints).. or 2.. it wouldnt
make the rpm... its making some rpm (I dont know how many
rpm he is turning) so at idle/just off idle he shouldnt
see any issues at those rpms... he HAS to put a gauge on
it to see what his back pressure TRULY IS and work from
there.. when I was testing all sorts of exhaust I did see
a system blow the pipe off during a test.. needless to say
we didnt use that system.... the nice little inward roll on
the exhaust tip(on the chrome tips) was a 3hp loss with just
that inward roll on the tip(thats back pressure due to flow
loss).. most people would never think that would be a issue
EDIT
to check the idea of the mixture going lean.. one way
to test that.. pull the exhaust off(open it) and run
it with a A/F meter... On my Rampage I went with elec
dumps just so I didnt pull the exhaust but yet reduce
the back pressure

My question was really meant to be rhetorical.

And I also went with electric cut-outs because getting a relatively quiet exhaust to flow my 500" engine kept getting more and more complicated and more and more expensive. And frankly, the only way to truly know what combo was going to work, was to install it and test at the track back to back. But that would require buying a lot of pipes and mufflers besides being a bunch of work.

The Doug's cut-outs are sure-fire at the track and are a lot of fun at shows and cruises. Plus, I get to listen to the radio and/or talk to my passenger while driving down the road.

I would suggest swapping the top and second emulsion holes, plug the top, .029 in the 2nd. And are you sure about the .091 bottom? I would try plugging it, way too large.

Ok, First, the run I posted is with open headers ( no back pressure on the exhaust side). On the carb side, the dump valve ( anti-surge valve ) remains open (Dumps air to atmosphere )until the manifold goes in to pressure - so my lean condition ( about 1200 to 2000 rpm )occurs while the manifold is still under vacuum. Even doing a burnout ( see posted run ) the engine is still under vacuum. The minute I floor it, vacuum drops to 0, dump valve closes, and manifold goes in to pressure - and lean condition goes away. Yes, I am sure about the emulsion sizes I previously posted. So, I went ahead and drilled out the 2nd emulsion hole ( previously plugged ) to .026". Four holes ( top to bottom ) are now .029, .026, .026, and .091. Just ran the car that way. Virtually no change. Lean spot is still there. A/F reading at idle might have gone a little richer ( 12.0:1 to 11.5:1 ). Still open for other suggestions. FYI, shifting at 7K. Will probably go back to how it was and try something else.

Talked with Patrick over at ProSystems yesterday. They are my original carb builder. He wants me to pull out the primary side PV and plug it (sec side is plugged) and jet up to the sec side jet size. I will give this a try next.