IML: '67 Carter carb flat spot

[therichardsonfamily@xxxxxxxxxxx]

Here's a question for the carb tinkerers (hi Dave):

'67 Imperial 440, w/ Carter AFB - the model that went on HP engines w/ bigger secondaries.  Idles smoothly, idle screws adjusted.  At WOT she goes like a r__ed ape - rubber in 2nd gear with a 3:55 suregrip.

18 inches of vacuum at idle - gauge moves just like it should when I rev the engine - as per the IML website (which is really neat, BTW - everyone should look at that page!).

Timed at 12 degr. BTC - new chain & gears - Mallory dual point distributor - mechanical advance appears to work - if I suck on the vacuum advance, it also moves timing forward.  Have not found a shop with a distributor machine yet.  Plugs are new - wires & cap are not (I'll get them on soon) but seem to be OK.  Again, she's a rocket with my foot in it.

I have a flat spot from about 1/3 to 2/3 throttle.  I see no black smoke during this flat spot.  Carb has been rebuilt (by an amatuer - me), and seems ok.  Choke is open when warm - linkage adjusted correctly - accelerator pump seems to work right - bowl vent closes just beyond idle - VERY low exhaust restriction (i.e. 2 glass packs + small resonaters out the sides)

So... the question is - how do I fix the flat spot?  Smaller metering rods becuse of the open exhaust?  Or is there something else I may be missing?  Throw some old school thoughts at me to try and tweak it.

Thanks, as always, for the help,

Dan Richardson
300L Family Heirloom

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