Adam,
I have not heard of the brand that you are talking about Lowes 21" I know Rover/Victa and Honda.
As to the Briggs & Stratton engine information I have put a link in one of the post to Redeye. If you do a search on the board in four stroke mowers you will find the link.
If you don't know the correct brand of the mower then post a picture on the board and we will try to help with the information that you require.