* Internal components: The crankshaft, connecting rods, pistons, and valvetrain are all designed for a specific RPM range. A stock, relatively low-compression 440 intended for a large, heavy car might only rev to 5000-5500 RPM reliably. A race-prepared 440 with forged internals, lighter components, and aggressive camshaft timing could easily reach 7000 RPM or more.
* Cam profile: The camshaft dictates valve timing and lift. A high-performance cam will allow for much higher RPM than a stock cam.
* Induction system: The intake manifold and carburetor (or fuel injection system) must be capable of supplying enough air/fuel mixture at high RPMs. A restrictive intake will limit the engine's ability to rev.
* Exhaust system: Similarly, a restrictive exhaust system will hinder high RPM performance.
* Engine build quality and tuning: Precision balancing, meticulous assembly, and proper tuning are crucial for high RPM reliability. A poorly built engine will likely fail at lower RPMs.
In short: There's no single answer. A stock 440 might redline around 5000 RPM, while a highly modified racing engine could easily exceed 7000 RPM. Anything in between is possible depending on the build.
