I replaced my stock Carter AFB with an Edelbrock 600 cfm performer series carb (on my stock 326). There were two heating tubes that came out of the manifold and into the Carter. These were metal tubes that were compressed on the ends where they slipped into the holes in the manifold. They were held in place only by the fact that they were stiff and fixed in place by their attachment to the carb (the holes are not threaded).

In the picture ( LINK TO PICTURE ), you can see the holes just below the choke linkage. I've added a big yellow arrow for reference

How do I plug these? Thanks!

I've been told that these holes are really just two ends to the same "tunnel" and aren't actually open to the inside of the manifold and, therefore, do not need to be plugged. Does anyone know if that is the case?

That's what I thought.
Jim

Compressed air will tell for sure. But wear eye protection.

Good idea Yellowbird, thanks!

I've got same carb, and no plugs. Every port has a line connected, so let me take a look and post a pic.

Oh, apologies Augy. Do not have same intake as yours. Just looked at your pic.

The Carter used a hot air choke; with a filtered air source at the carb running through a tube to one of the tubes in the manifold. The unit in the manifold is a "U-tube". Then the original had another tube running from the second tube in the manifold to the heat choke on the carburetor.

The manifold unit OFTEN burns out from the raw exhaust that surrounds it, and unplugged, would be an exhaust leak.

PS - the original Carter will perform MUCH better!

Jon.