Vacuum Ports on 5.0 back of engine?

[Kain81]

Hello - new to the forum. Bought an 1983 T-Top Hatch last week and found a few vacuum ports missing hoses.
Can anyone help me figure out where these go? A photo would be greatly appreciated.

Thanks in advance for the help!

-Waylon

[qikgts]

Welcome!

I'd guess one was for ported vacuum (dizzy) and the other, maybe for an upshift light but I'm not 100% 83's had one. Either way, considering the intake is aftermarket and other stuff is likely changed from stock, I wouldn't worry about them too much.

How about posting up some details and pics of the car? Again, welcome to the site!

[Kain81]

Welcome!

I'd guess one was for ported vacuum (dizzy) and the other, maybe for an upshift light but I'm not 100% 83's had one. Either way, considering the intake is aftermarket and other stuff is likely changed from stock, I wouldn't worry about them too much.

How about posting up some details and pics of the car? Again, welcome to the site!

Thanks - i capped them just to be safe.

I guess i can do an introduction post in the general forum.I'll do that now.

_Waylon

[WilliamCapri]

Welcome to the site!

Those are vacuum control valves tagged VCV in the vacuum diagrams. They are screwed into a water passage that runs between the heads so they don’t really cause a problem for the engine’s vacuum. A vacuum source would be plumbed to a port and when the engine warms up the valve would shift and allow vacuum to pull on the other ports. Plugging them doesn’t make a difference. Vacuum diagrams can be found here, just use the search and don’t forget to type in the key at the bottom of the search page.

[JACook]

One of those was used to provide manifold vacuum to the distributor during warmup, then switch to ported vacuum
once the coolant temperature reached ~160F. This raised the idle speed during the period where the fast idle cam
was disengaged, but the engine wasn't yet warmed up. On cars with an Upshift light, this valve would include an
electrical switch on top, to inhibit the light when the engine is cold. (The Upshift light itself was controlled by a
vacuum switch on tha back of the driver side strut tower, along with RPM input.)

The other thermal vacuum valve was used to inhibit EGR until the engine reached normal operating temperature.
EGR vacuum was also used to operate the exhaust heat riser valve, air pump diverter, and vapor canister purge
valves.

[homer302]

No need to cap them. If no vacuum is going in, none can go out. They are just useless intake plugs at this point. Maybe not so attractive but not harmful either.