What is this part?

[Festiva Time]

The hex part is the carb manifold's secondary (or is the primary?) throat lining.

[drddan]

Yes, it is on the secondary.
My concern is the heater plate originally is directly against the bottom of the carb. If I try to use it now, it will be 1" away from the bottom of the carb, under the 1" thick adaptor plate, and the gas will then have to make its way thru/past this hex piece, which now seems like a huge obstruction sticking out into the fuel path, interrupting the flow. The hex is a smaller I.D.than the opening on the carb.
Or am I being unneedlessly concerned about the fuel path/flow?
I am mating these adaptors so that all is smooth thru the adaptors with no "hard" edges. The opening shapes between the Weber and the Festiva differ, so I am "blending" the openings of them to make one smooth chamber inside, rounding the edges of the Festiva "hourglass" shape on the Festiva side of the 2 pc adaptor plate.
Someone have advice or input about the use of the heater plate with the adaptor?

[jmye1524]

There are a few peeps on here that have Weber carb's. Did any of you re-use the heater plate on your Weber. If not, were there any problems without it.

I've had no such problem..

.

[drddan]

^^^ Thanks! I see your in Indiana. We get about the same weather conditions here in Missouri, so I dont expect any problems without it. Don't want to use it really.
I'm curious, what kind of adaptor are you using?