Coolant and heater terms are sometimes used interchangeably. A hose of the appropriate size and shape is important. Many older American cars used generic hose for heater connections, but in the Z-cars those hoses are often molded into specific shapes. Any hose that's molded into curves or 90 degree angles should be replaced only by a matching molded hose.

Fuel injector hose is a specific type, and in my experience it's the same size for most cars, but rated for use with fuel injection. It has to withstand gas and high pressures.

Clamps for FI hose are typically NOT the same shape as for coolant hoses, but are shaped to provide 360-degree contact. Here's an example: HPS 100% 304 Stainless Steel Fuel Injection Hose Clamps

 

Gotcha, so if I find a heater hose of the right diameter it's likely fine to use in the external bypass. Trying to figure out the right size for the different connections has been a pain, and I can't find any sizing in the FSM.

I need to buy that 90 degree elbow hose and don't want to throw away $25 on a molded hose of the wrong diameter.

Thankfully I got all the right stuff for the fuel injector swap out including the right clamps. But these hose sizes elude me...

 

You can still get fuel and heater hoses from NIssanpartsdeal.com, there are some still available. get 'em while you still can.

 

Ensure you do use quality hose, and of course of the correct diameter. Not all generic hose cut-to-length from any Manny-Mo & Jack Auto parts is what you want.

NPD @ www.nissanpartsdeal.com also still carries vacuum tubing as well as quality Coolant hose, if not the per-formed pieces as mentioned.

Close enough isn't good enough, try BelMetric, click here: Belmetric.com for raw stock hose and clamps designed for MM sizes.

I gave up guessing hose sizes and bolt diameters a long time ago. A digital vernier caliper is your friend to the nearest .02 MM, and of course you'll be able to calculate the required interference fit for a leak proof install.


Hope this helps!