As stated, the spacer is a heat isolator. If your trucks runs without any problems without the isolator, you probably don't need one. In high heat settings where the engine is subject to heat soak, then an isolator will help on restart. All engines need heat under the manifolds to help vaporize fuel and keep it from pooling on the intake floors, but having a hot carburetor is not ideal. The fuel heats up, expands, and can over power the float leaving a flooded engine, this is where the isolators come in handy, they keep the carburetor at lower temperature while the engine is cooling down. Spacers can help tune an intake and carburetor combination, but in the 216's case, they only serve as a heat isolator. Out on the road, you won't know the difference. Just be sure the gasket has the correct cut out for the vacuum signal on the bottom of the Rochester.
Joe
