What is spark plug gap for Craftsman Eager 1 3.5 HP lawnmower?

The "rule of thumb" spark plug gapping for single cyl engines <13HP is 0.025 - .032. Average gap is .028, and incidentally most plugs come with workable or accurate even gaps from the factory and likely for this engine will take a champion CJ7 or CJ8 series plug. Ok, on to adjusting. Get a real feeler gauge set. Don't use the circular beveled disks that are sold in any parts store or automotive section. they're horribly inaccurate and can be fairly diffacult to use. select the appropriate feeler gauge (or combination of feelers) and attempt to insert into the gap. if it clears easily the gap is too large. very gently tap electrode ground on a solid clean surface rechecking often. When insertion exhibits some resistance you're golden.