This is my first post. I bought a 96 Z28 that the previous owner had removed the heads to have the valve seals redone. I am in the process of reinstalling the heads and had a few questions since I was not the person who removed the heads. I know there is a water crossover pipe that bolts to the rear of the heads. There are a few other bolt holes. What are these others holes for? These holes seem to be the same on the front and back of the heads but on the front they are plugged with Allen screws.

Any help you can offer will be greatly appreciated.

 

The plugged holes are unused coolant holes on the front of the heads cause the steam holes are only needed on t he back, but each head is the same so you could turn them around if you want and move the plugs to the other side. Each head also has a hole on the side for a temp sensor which is the driver's side on your car, the other one should be plugged. Other screw holes are just for the alternator/PS bracket on the pass side and the coil on the drivers side - maybe the air pump too - I cant remember. The back of the drivers side head also gets a hole for a bracket that holds the O2 sensor connector and acts like a heat shield too.

 

Thanks that will help quite a bit.

One more question if you might know. Where are each of these going to be attached to? I feel like a real bonehead asking questions like this but not having taken the heads off in the first place I'm working blindly.

 

Look at this pic and you will see the steam pipe attached to the back of the heads.

 

Excellent pic shoebox. The part that has been very confusing to me is that the heads I have seem to have holes in a few locations that are not pictured. There is a series of three holes just outside and down from where the crossover tube is connected. All three holes are threaded and the center one in each of the series is larger than the two outside of it. This is the same on the front of the haeds only on the front these larger holes are blocked off. I'm wondering if I am just missing two plugs for the other side of the heads?

 

You shouldnt have any other holes going into the water jacket other than one on each end of each head, with the fronts being blocked off and the rear holes going to the steam pipe, and of course, one on each side of each head, again with the pass side blocked off and the driver's side going to the temp sensor. If you have unused blind threaded holes - no big deal.

 

Sounds good. Thanks for all the help guys.

 

Hi

Here's a link that might help. http://www.automotiverebuilder.com/ar/ar99928.htm
It says this : There is an extra hole that goes into the water jacket on both ends of the heads. These should be plugged when they’re in the front, but left open when they’re on the back. There’ s an external coolant transfer line that connects the holes on the back side to a reservoir that vents the air and steam vapors that would be trapped in the head and cause hot spots.

roadgod