I have a rebuilt 350 going into my z, and noticed a threaded hole in the drivers side head between the 1 and 3 cylinder exhaust ports. The hole is there on my old 305, but it is plugged by something. Can it be left unplugged? What is it there for? Thanks for your help
Matt

 

it is for a temp sending unit or a 1/2 or 5/8 inch npt plug IIRC.
it is a hole into the water jacket, do not leave unplugged unless you plan on shooting antifreeze all over your engine bay.

 

Are there any more of those that i should be looking for? I guess im fairly lucky i found that one, where are the other ones? Thanks for the help.
Matt

 

one in each head plus maybe in the intake. 3/8 or 1/2 pipe threads