Does the open side of the cup of the neoprene oil seal go towards the engine or towards the radiator? I just bought an Anderson timer and it doesn't tell you which way to install the seal. I pulled out the felt and it seems like the seal can go in either way. thanks for helping a novice replace an 90 year old timer!

The open side of the seal always goes toward the fluid you want to keep in. You may need to use some RTV to secure the seal as sometimes it doesn't fit tight enough.