I have a small hole in the cylinder head water tube of my '77 280Z. Any suggestions on patching the hole or where to find a replacement tube?

What is the cylinder head water tube? Cut a picture from the internet or take one with a camera, and post it.

Probably the tube through the intake manifold. Coolant goes from BSPT hose barb in lower thermostat housing to BSPT hose barb at front of intake manifold, through the tube, to Hot=closed thermostat, to short hose, to metal tube at back of engine, to short reducer hose, to the tee on the right side of the block.

If it's the tube through the intake manifold, you can (maybe) buy a used manifold with good heater tube, or take it to a good machine shop. Otherwise plug the thermostat housing and cap the tee on the right side (rubber tapered plug and/or silicon cap). Those tubes get all corroded and beyond repair.

If it's the tube around the back of the engine, buy a new one (expensive), or use some good heater hose instead.

It is the metal tube that goes around the front of the engine, item #51 in the schematic attached and the picture attached shows the tube where it goes under the radiator hose. It is the white area.

I don't know if I picked the right pipe, but your dealer might have better microfiche. You can't tell if it's really available until you place an order though.

I picked #56 - Datsun 280Z Cylinder Head, Rocker Cover & Thermostat L28E

PIPE WATER :: Nissan Parts, NISMO and Nissan Accessories - Courtesyparts.com

Should have read more carefully. Saw some silicon tape at O'Reilly supposed to temporarily repair leaking water hoses and pipes, but that looks so corroded it probably won't work.

I've used water activated fiberglass mat, avail. in the plumbing section of Home Depot, to temporarily repair an old leaking hot water pipe in my house. It is made for leaking pipes & marine applications. It held up to the heat & pressure just fine. Might be one of those repair items to tuck into a tool bag too. Mark