305 V8 - Rusty spot on intake manifold, with ports that nothing is connected to

[escortwagon]

Hi everyone! Another question about my new to me engine, and thoughts would be appreciated. On my '85 305 V8, there's a rust spot in the middle, and it has a couple ports that look like tubes would attach, but they don't have anything connected.
I think the rusty spot is where the exhaust crossover is, is that right?
Any idea what the 2 tube ports are for? Should something be attached to them?

Thanks!

 

[Bt Doctur]

standard auto intake manifold with the heat port for a choke element.
Not used on boats

 

[alldodge]

It use to have a heat pot type choke for the carb. It was changed over to the electric choke so its no longer used

Edit: BT has better explanation

 

[Lou C]

That area gets pretty hot and was used for the heat tube for the choke on the old 2bbl Rochesters and the divorced choke spring for the 4bbl Quadrajets.
The way the hot air chokes worked was that there was vacuum in the choke housing, and it sucked fresh air through that tube which was actually inside the exhaust crossover, and the hot air, unwound the choke spring. Same thing on older Holleys and Ford Autolite carbs.

 

[escortwagon]

Thanks for the info!
So, is exhaust leaking from that then? Should I replace it with a plate without ports that blocks it off? (Assuming those rust bolts don't just break off if I try to remove it...)
The boat is on the trailer for the year and winterized, so I won't be running it until spring thaw and can't check and see if anything is coming out.

 

[Lou C]

If you can that would be a good idea. They do make block off plates. Those old style manifold heated chokes do work fine as long as you keep the choke plate & linkage clean.

 

[Drcoffee]

There is no exhaust near that rusty bit. It was a mount for a choke assembly. Just remove it and repaint the intake to stop the rust.

 

[Lou C]

Actually it is the exhaust cross over. There are exhaust gases passing through there and under the carb. Here's a 4.3 V6 version of the intake...
And a pair 4.3 pre-Vortec cyl heads....that center opening between the intake ports is an exhaust passage....some of the exhaust gases are routed through this passage to heat the choke tube or the area underneath the spring for the divorced choke. This is how all the chokes, be they hot air vacuum or divorced well type chokes worked on GM cars going WAY back to the old days. This was eliminated on Vortec engines so that's why you have to use an electric choke.
The "right" way to take care of this is to use a block off plate.