[firstgenaddict]

They are not wood, they are PHENOLIC spacers.

The following is from -
https://www.onallcylinders.com/2014/...uretor-spacer/
Spacer Materials
Let’s start with a spacer’s insulation properties. These are largely determined by the material a spacer is made from. There are four typical types of spacer material: wood, phenolic resin, polymer (plastic), and aluminum. Each has a different thermal conductivity (heat transfer) rating that tells you how well the material insulates against heat. The lower the rating number, the better the material insulates. Let’s look at each type:

Aluminum is the worst insulating material of the bunch, with a thermal conductivity rating of 1,665.1. An aluminum spacer does offer three advantages—it’s very durable, is easily altered to help tune the intake charge, and is the only spacer material allowed by many racing sanctioning bodies.

Wood is the best insulating material, with a thermal conductivity rating of 1.02. It’s also cheap and easy to shape. However, a wood carburetor spacer is the least resistant to gasoline and chemicals. It soaks up liquid easily, causing the spacer to warp, become porous (causing vacuum leaks), and break down faster. If you use wood spacers, inspect them regularly and replace if necessary.

Phenolic Resin has a thermal conductivity rating of 2.01. While not as good an insulator as wood, it is far more resistant to fuel and chemicals, making a resin spacer more durable.

Polymer is less expensive than phenolic resin. But with a thermal conductivity rating of 3.90, it does not insulate as well. Some polymers have been developed that insulate nearly as well as phenolic resin, so it pays to do your homework before you buy.