stringer core material

[Galey]

What material did GB put in the core for stringers and engine mounting? Did they use wood, and if so, would you drill through to mount with bolts, or be able to use lag screws? (mounting by-pass oil filters?) Thanks

 

[GB42-424]

Stringer core

My 74' is foam filled. Same foam you see around the limber holes that pass through the engine mount stringers. Suggest you enlarge our hole and fill with thickened epoxy.