3. When is the thermostat housing spacer (OVWJ_13_241) used? I haven't run into one on any engine I've worked on. And do I need one with the bronze casting and current 180 deg stat.

You only need the spacer if the top of the head is badly corroded, to the point that the base of the thermostat won't be able to prevent water from forcing its way up and around the thermostat. In these cases, the thermostat will see the top of the spacer as a new head and work just fine.

There are also some aftermarket thermostats that require the spacer due to the fact that their operating mechanism is a bit too long and they contact the floor of the cooling jacket within the head.

It's important to note that the spacer will require the use of manifold studs which are long enough to accommodate the thickness of the spacer.

You will not need a spacer for our bronze housing. - Updated: January 3, 2004