Uncapped Vacuum Tee? EGR?

[NJBronk]

Noticed this when changing distributor cap…. What is this vacuum tee for? EGR? I have long tube headers / assume EGR system was removed.

The nipples seem to be open - I’m assuming they should be capped?

 

[Broncobowsher]

Irrelevent.
That is a thermal switch. The 2 ports connect when a specific temperature happens. Ideally unscrew it and put a plug in the hole.
Caps will make it look cleaner, but won't change the function.

Just realized that is in an intake runner. That might be a more weird valve than I was thinking. Remove and plug is best. If there is any vacuum on the ports it needs a removed or caps. A quick loop of vacuum hose between the two would be the really quick fix until you (never) get around to removing it.

 

[NJBronk]

Irrelevent.
That is a thermal switch. The 2 ports connect when a specific temperature happens. Ideally unscrew it and put a plug in the hole.
Caps will make it look cleaner, but won't change the function.

Just realized that is in an intake runner. That might be a more weird valve than I was thinking. Remove and plug is best. If there is any vacuum on the ports it needs a removed or caps. A quick loop of vacuum hose between the two would be the really quick fix until you (never) get around to removing it.

I’m confused - what the heck is it for??

 

[Broncobowsher]

Not sure what it is for, but can tell you it does nothing the way it sits now. At best, it is just a plug. At worst, a vacuum leak to that one port.

 

[DirtDonk]

Can you get a wider shot please? It’s a very unusual place for any kind of a vacuum port.
And sitting so close to the distributor as it does, in theory it should be a coolant passage, as was originally thought.
Even though Weiand is known for having some unusual variations on their versions of the Ford manifolds, that still It’s a strange set up.

 

[DirtDonk]

Oh, and what year is the bronco? 73 and later obviously, if it had EGR.
Just curious.

 

[NJBronk]

Can you get a wider shot please? It’s a very unusual place for any kind of a vacuum port.
And sitting so close to the distributor as it does, in theory it should be a coolant passage, as was originally thought.
Even though Weiand is known for having some unusual variations on their versions of the Ford manifolds, that still It’s a strange set up.

It’s a 1974.

Here are some other pictures. I just capped it for now, just in case there’s some vacuum there…

 

[DirtDonk]

Thanks. That helps.
As said, that’s a an intake runner so is a vacuum area. Making that thermal vacuum switch that you’re questioning about simply a plug.
If you can find a suitable sized plug you can replace it. Or just do what was suggested and either leave it, or if you determine the vacuum is leaking into it, loop a piece of hose between the two ports.

Speaking of hose, what is that larger hose next to the distributor? it looks to be in the coolant passage that I was referring to.
That’s usually where the engine coolant temperature sensor goes for the factory gauge.
Or at least it’s one possible spot.

 

[DirtDonk]

Where is the brake booster getting its vacuum from?
I just noticed that at the back of the intake, manifold, in an individual runner, there is a plug.
This location is usually for a vacuum manifold, or “vacuum tree“ to connect things like the vacuum booster and other needed accessories.

 

[Broncobowsher]

It also looks like your vacuum advance hose for the distributor is disconnected and just sitting on the intake under the coil. I don't see anything on the ported vacuum on the carb, so it probably just got knocked off and not put back on.

 

[MarsChariot]

That looks very similar to the spark delay thermal valve that is mounted in the water jacket on a stock intake manifold. If I had to guess, and it looks like a late model with the stock vacuum booster ,I would say somebody took it off the original manifold and stuck it into the nearest hole it would fit in. But being in an intake runner is of no use for its original purpose.

 

[NJBronk]

Where is the brake booster getting its vacuum from?
I just noticed that at the back of the intake, manifold, in an individual runner, there is a plug.
This location is usually for a vacuum manifold, or “vacuum tree“ to connect things like the vacuum booster and other needed accessories.

There is another tee with lots of plugs (including bolts stuck in hoses that I may replace with proper caps), and the brake booster hose comes off the top:

 

[NJBronk]

It also looks like your vacuum advance hose for the distributor is disconnected and just sitting on the intake under the coil. I don't see anything on the ported vacuum on the carb, so it probably just got knocked off and not put back on.

Yes, I noticed that for the first time when my carb flooded. The nipple on the carb is plugged. I tested the vacuum advance by sucking on the hose and it seems to work, so once I have the carb rebuilt I plan to set timing and then plug that hose back on and see what happens…

 

[DirtDonk]

There is another tee with lots of plugs (including bolts stuck in hoses that I may replace with proper caps), and the brake booster hose comes off the top:

Great. Plenty of vacuum sources then.
And I hate to say it, because the bolt and a hose method looks so janky, but it’s often better than the caps.
Old caps are pretty good, but modern replacement caps often deteriorate and fail within just a few months.
Causing lots of vacuum leaks that you sometimes have a hard time finding because you think the newer parts could not possibly be at fault.
A common problem with lots of parts these days.