I've always wondered what this bolt in the TPI manifold is for...the one in the picture below that's next to the water neck and the fuel injector. It's straight up and down and doesn't thread into the cylinder head; it's just a blind hole.

 

Someone else in here might have a better idea of what it is. But the only thing I can think of is that there are three more of those holes around the engine and they are hoist points for removing the engine.

 

an unused mounting point for an AC compressor / alternator brace.

 

Yep he is right. There is a bracket that connects the back of the alternator to the manifold.

 

Yep!
There's also a brace that connects the bottom of the alternator and the stock exhaust manifold.

 

Well, on my car there is a Y shaped standoff that bolts on there, the large line from the evap cannister sits in the Y and it goes to the pass side of the throttle body.

 

yours appears unused for original purpose as was mine.
i replaced it with a standard bolt for cozmetic puposes only

 

it along with the two intake bolts are also used to mount a lifting eye.ya know something to yank yo moto out

 

Hmm. I've never paid attention to those on the serpentine 88-up cars, but I did notice the 86 IROC had a lifting eye in the same place as an LG4 w/ 2 intake bolts + one attachment to the AC bracket.

 

On a camaro in stock form, that bolt was used for holding down the wiring harness that runs along the valve covers on the driver's side.

For a GTA, probably what the other guys said, I can't really say.

 

I had thought about putting an eyelet into it and using it for a lift point while I change motor mounts, but there really isn't much material around it. I'm pulling the exhaust manifolds to install headers anyway, so I'll just use an exhaust manifold bolt hole to lift the engine up.

I had always wondered what purpose the the mystery bolt hole had. I suspected it was used on Corvettes.

 

On mine it was used to hold a clip that holds the wiring harness that goes to the injectors and alt.

DO NOT use that as a lifting point. Think about it. Blind hole. ALUMINUM. Small hole. Big heavy engine. ALUMINUM.

 

Oh yeah, it took about 3 seconds to determine that wasn't a good idea. That's why I'm pulling the exhaust manifolds now and using those holes...gotta do it for the header install anyway.