This is a compilation of posts /white paper mostly by ACR, with some comments by me. While by no means full race mods, this is something most can do with some patience and the difference in performance may surprise you. The first pic is what he started with the second with one side partially cleaned. (This will give you an idea what can be done) My comments in bold.
After reading & re-reading Damon’s “White Paper” articles on carb mods I decided to give this a try. I thought it might be useful to share my experiences & photos with this Board. This will be an ongoing project, I will post new info & pictures as I go. Be sure you read Damon’s “White Papers” before trying any of these mods. esp the “Carb Modifications Part 1.” Also ANY ONE who has done this please correct or add to the info I’ve posted.

Standard Disclaimer applyies, I did this & it seems to have come out just fine, but I haven’t re-assembled or run my carb/engine. So if you do this it’s at your own risk.

Tools needed;
1.Asst. screw drivers,Torx head, etc. tools to remove air horn.
2.Files, abrasives, &/or Dremel tool to remove flashing & modify air horn. I prefer to use files first.
3. Specific files I use are 4″ Nicholson six file set w/handles, use chalk on the teeth before cutting. Make sure one of your flat files has a safe edge, (no teeth). I also used artificial or acrylic fingernail files/boards to smooth the file cuts, they work great & come in 100-800 grit. Get these at any Beauty Supply store.
The first photo below is what I saw when I removed the air horn, not a pretty sight. The venturi clusters & carb body were corroded & needed mild clean up with 240 grit, then 320 finger nail board.Most would trash this carb I suspect

This photo shows the amount of corrosion, or poor casting that I cleaned up with a mildy worn 180 grit board, followed by 240 & 320. I had to be careful to keep the original lines & angles.Be very careful not to modify the venturi shape

The next photos show the primary booster venturi with casting flash removed & 240/320 treatment top & bottom. I used Scotch Brite on the bottoms & insides that were hard to reach.Notice the casting bumps and ridge around the secondaries (circled) that were filed/blended)

Modifying the air horn. Remove the air horn & choke assmb. & locate the areas down inside the air horn where flashing needs to be removed, (flashing is the casting residue left down inside the air horn, like the stuff left on plastic model airplanes, etc).
This is fairly easy to do but requires some skill & patience.
Primaries- Remove the ridge of flashing located about 3/8″ down from the threaded rod hole in the center of the carb. The flashing looks like a small weld bead & goes around the inside diameter of the carb, file/sand it down flush. Also in there are two tabs for the choke plate, I removed them since I wasn’t using a choke but think you should leave them alone if you are using a choke or aren’t sure. Just remember the choke plate & rods are a big obstruction to air flow.
Secondaries- Remove flashing at the bottom inside edges of the air horn, & the flat area in the back side of the secondaries. If you run your finger over the air entry you can feel the roughness. Check your work, after all flashing is removed use 100 & 180 grit emery to smooth cuts. If you’re not removing the choke, radius all inside edges of the air horn except the center divider. That ends the first step in “Carb Mods 101″.
The next step, if wanted, is to remove the choke horn. You need to think about this & plan the best way for you to get this done depending on the tools & skills you have. For me, this was more demanding & difficult at first, but after I got started it went fairly well. These pics show stock, and beginning of the smoothing/ grinding. If you are keeping the choke horn , drill and tap the outide of the holes for 5/16-18 setscrews and loctite them in the holes




This picture shows the straight & angle work to promote smoother air flow into the primaries. Looking at the top of the picture, on each side of the (missing) pump jet location, you’ll see “before” (on the right side) & “after” on the left, angle blending of the carb body. The black line on the right side is from a felt pen. The other area done is the back side of the primaries,on each side the big hole for the threaded rod. That shows both sides cleaned up straight down to the venturis,compare these pics with the previous posts. You can really tell a difference in the slickness of the air entry areas when you run your finger or nails over the smoothed surfaces.

If you decide to do this be aware that the top lid, or air horn, that bolts to the body has some play in it & can be bolted down a few thousands or so “off” each time. You need to make sure it’s tightened down in the same location each time you work on it. I’d also suggest using masking tape on areas you don’t want scratched. I used a variety of small hand files & a Dremel cordless 10.8 volt tool for doing the early work, followed up with various grits of wet-dry or nail files. For me, the cordless/variable speed Dremel is MUCH easier to work with than corded models.
The next picture shows the ridge at the mating area as it is stock

And what it looks like finished…..Notice the SLIGHT rounding of the airhorn edges-sharp is not good on an air entry

Many thanks to ACR for his work-hope this helps to visualize the white paper…