Hole in water pump cavity in head
 

Hopefully the picture will show up and you can see the hole that is in the water pump cavity.It would be about 3:00 if a clock face. I just wonder if it goes through to where coolant is allowed in the head anyway or it needs to be plugged.There is another hole that I know is correct at the bottom say at 6:00.If coolant is on the backside of the hole that would be fine I guess but this is right in front of the stud that hold water neck in place on drivers side so I hope it is not allowing coolant to combustion area.

Re: Hole in water pump cavity in head
 

Is it a wet area where the hole goes? Probe it with a wire and find out. My bet is it is the wet water jacket. Does it need to be repaired? Since it is in the housing area of a centrifugal pump it night affect the pumping efficiency but the leak is to the place that it is going any way, might actually relieve some of the over vigorous pumping action. Fix or don't and / replace with new. I'd prefer to do a repair only once and have the option of a compression increase for free.

Re: Hole in water pump cavity in head
 

Is that a crack next to hole ?

Re: Hole in water pump cavity in head
 

Like you, I have only the picture to go by but I think what you are looking at is a join in the mold used to make the casting core.

Re: Hole in water pump cavity in head
 

It is a mould line. I do find that blowing air into the hole it is coming out in the head water cavity.

Re: Hole in water pump cavity in head
 

I agree with 100IH, don't worry about it, as it might actually help the overactive water pump.
Otherwise, a new 5.5 head is an excellent choice for more power. Best bang for the buck.