With gratitude to the late Tony Bingelis, here's a detail of an easy-to-fabricate baffle that goes in the space between the cylinders on a small block Continental. The purpose is to direct cooling air down around the base of the cylinders, stopping it from dumping straight down through the "slot" between the cylinders and creating hotspots on the undersides. This is for cooling air coming in from above, as is the setup on almost all engines with a pressure cowling or with "eyebrows" like on a J-3 Cub.

Here's a photo of how they look on my Pietenpol with A-65. All-thread with metal locknut (no nylon locknuts should be used ahead of the firewall unless outside the cowling)