camshaft replacement on Craftsman T2600 Riding Mower

[tymoss96]

I have a Briggs and Stratton engine for a Craftsman T2600 riding mower and I am doing a cam shaft replacement due to not enough compression. i got the engine housing taken off with but when it was taken off I discovered a key piece that is flat on one side and rounded and half geared on one side. any advice on where this piece would go would be greatly appreciated, I will attach pictures to the post.

 

[Rivets]

Looks like parts of the ACR, automatic compression release. It is part of the camshaft, so you will have to replace the cam.