HIF-4 Carbs Running Lean

I've finally gotten my B running so I'm down to fine tuning everything. My carbs are running lean. I have the adjustment screws completely rich and it's just a little too lean still. When I have the choke pulled slightly out it runs perfectly. Is this something that I can fix with an adjustment or replacement part or is this more indicative of a vacuum leak? I did have the wrong needles in and I just went back to the proper needles for the carbs. I've also got the distributor set to about 15deg if that helps at all.

For starters, I would examine the jets after dashpots are removed and confirm that they
are indeed all the way down and moving w/adjusting screw. They could be hanging up.
RS

Check your float level. Too low a level will result in a lean mixture you can't adjust away.

The jets do move up and down, they're also new, just replaced last year. I'll check the float levels again, there is a good chance they're set but not quite where they should be. I know when the carbs are flipped over the lowest point should be 1/8" below the bottom of the carbs. What's the best was to measure that? I've kinda been guessing with a straight edge.

Double check your manual (what are you using?) on that float level. There is a part of the float that should be
a smidgen ( .04" ) below float face.
Maybe your poppet valves (over-run valves in carb disc, if original) are stuck open. Do you still have those on the butterfly?
RS

Yeah, I still have the original valves. I've checked them and they worked fine. I went ahead and soldered them just to make sure and I think they're sealed pretty well. I plan on getting new ones without the poppet valves sooner or later.

Also check around the carbs and various hoses to see if you have a vacuum leak. That can give you a lean condition.

To set float levels on my hif s i used a 1/4 extension with the proper thickness elect "tie wrap" in the middle of 6 in ext.
as a float gauge

Float level adjustment as described in the book won't work because they stopped using the adjustable "brass tang" and never edited the book.

Jimmie Hilton has/had floats for newer carbs that have brass tangs. Special order from England, as I recall.

How to adjust the floats that do not have tangs: you can't. you can only shim the needle seat.

I use thin nylon washers (about 30 thou thick, as thin as I can find) and place them under the seat as it screws into the float bowl lid. One is all I use. And I accept what it gives me and don't bother thinking about what the level measurement is or ought to be. Because it is not attainable with available parts unless you have a supply of very thin washers.

Here's also my thought on what the level should be...since the book's instructions are clearly incorrect.

With the bell and piston out of the carb, and your eyebones looking down at the hole in the jet you will see fuel down there. The fuiel level in the jet is the same as the level in the bowl as the two items are connected at the bottom by a hose. When fuel level is too high in the bowl, it is too high in the jet as well.

Take a piece of small plastic tubing and place one end on top of the jet so that when you blow into the tubing softly you are blowing into the top of the jet. give it a gentle puff and quickly remove the tubing at watch the fuel level in the jet. The puff will have pushed it down somewhat, but it will surge back up as it seeks to restore it's former level. If this surge brings it high enough that it floods over the top of the jet then the level in the bowl it too high. It should just come to the top of the jet, maybe a tiny bit of flooding, maybe not quite flooding. If this is what you see, the level is about right. if it floods, the level is too high. If it does not get close to the top of the jet, the level is too low. Fiddle with the washers to adjust further as needed.