Rebuilt Carb, now have hesitation off idle

[IH8Z28S]

I have a 17059272 carb that was originally on a 301 and now a mild 400.  I spoke with Cliff and he sent me the kit with everything he recommended.  If I hit the pedal hard I have a big hesitation off idle, but once it gets past that it runs great with no hesitation when the secondaries open.  I set the idle mixture screws 3 1/2 turns out, do I need to go further?  I used a vacuum gauge and am getting about 18 in-lbs.  I did notice that the new main jet was solid and my old one had slots cur out of the sides, does this matter?

[quadrajam]

The solid fuel inlet seat is preferred over the slotted seat due to fuel drain back issues
but not your problem. Might be accelerator pump problem ...Run the engine for a few seconds
and shut it off. That will make sure the bowl is full. Then while shining a light down the bores
look for a strong stream of acc. pump fuel on both sides. You may have to prop the choke
blade open to get a good view. It should spray immediatly as the throttle blades start to move and continue through the entire stroke. If not get back with us.
 
 If the acc. pump link is in the outer of the 2 holes move it to the inner hole & try.

QJ
   

[Kenth]

The "windowless" fuel inlet seat was introduced 1975 in the M4 units for better fuel control inside the bowl.
It has NOTHING to do with "fuel drainback issues".

The advantage with the slotted inlet seat is better flow into the bowl.

FWIW

[IH8Z28S]

I messed around with my idle mixture screws and turned them out with little change in the vacuum, so I ended up about 3 1/2 turns out, seems to have solved my issues.  Cliffs kit and parts really woke it up, I'm extremely happy with the change!

[quadrajam]

Excelent!

Qj

[Cliff Ruggles]

The solid fuel inlet seat doesn't allow the carb bowl to drain back nearly as low as the "windowed" variety after shut-down and it helps with fuel control inside the bowl as Kenth mentioned.  Every little bit helps these days as the evaporation rate is high with this new fuel......