On a 1990 Chevrolet distributor cap, the number 1 cylinder location is usually marked directly on the cap itself. However,
there's no single, universally consistent location. The position of #1 varies depending on the specific engine (e.g., V6, V8, small-block, big-block) and even sometimes the slight variations within engine families.
To find #1, you must consult a repair manual specific to your 1990 Chevrolet's engine. The manual will have a diagram showing the firing order and the corresponding number locations on the distributor cap. Looking at the cap alone won't be enough; you need the engine's firing order to correctly identify #1.
