Doug and Mal are doing some work on Doug's R51/3.
The engine had the old single pin breather plate.
Given their reputation for failure, seemed that a new style breather plate would be the ticket.
Following are some photos taken while Doug and Mal modified the old style 20 degree cam gear to accomodate the new cast in pins breather plate.
Pic 1 - gear with new breather plate
Pic 2 - Interference fit plugs used to fill old over sized holes. .03mm interference fit. The plugs have a lip which prevents them migrating out the back side of the gear and the washer in the front prevent escape forwards. Gear was heated to 250F and the plugs were still a press fit. They probably won't be moving anytime soon.
Pic 3 - The old gear with the 15mm oversized holes plugged
Pic 4 - Using an old cast in pins breather plate we were able to drill pilot holes. vertical pin links the location of the 5mm pin hole.
Pic 5 - The fixtures we turned up so we could hold the gear at various stages and drill the right sized holes in the right place. You can note the new smaller 12.25mm holes.
