Abstract: A valve bridge adjustment tool has top and bottom sections disposed in fixed relation to each other and preferably made of steel or another durable metal alloy. The bottom section has a U-shaped recess with an open end that is releasably engageable with a knuckle of a valve bridge to stabilize the bridge whenever a jam nut is either loosened or tightened. The top section comprises a hexagonal outer wall and a substantially cylindrical bore adapted to receive the jam nut upwardly through the, U-shaped recess into the bottom portion of the bore, with sufficient remaining clearance around the jam nut to permit insertion of a pass-through socket into the top of the bore and into engagement with the jam nut. The subject invention is especially useful with many internal combustion engines having four valves per cylinder.