* A legendary small-block Chevrolet V8: This is probably what most people think of when they hear "350." These are known for their relatively simple design, robust construction, readily available parts, and tunability. They're a popular choice for hot rodding and modifications. However, even within this category, the quality can vary dramatically depending on the year and how well it's been maintained. A well-maintained example can be excellent, while a neglected one might be a disaster.
* A different manufacturer's engine: Other manufacturers have produced engines with 350 cubic inch displacement, but these might not be as well-regarded or as readily supported as the Chevy small block.
* A very old engine: An older 350 might be less fuel-efficient and less powerful than modern engines, and it might require more maintenance.
To determine if *a specific* 350 engine is good, you need to consider:
* Make and model: Is it a Chevy small block, a different manufacturer's engine, or something else entirely?
* Year: Older engines may have different characteristics and maintenance needs.
* Maintenance history: Has the engine been well-maintained? A poorly maintained engine, regardless of its size or make, will likely have problems.
* Intended use: What will the engine be used for? A 350 might be perfect for a classic car but unsuitable for a modern fuel-efficient vehicle.
* Condition: Has the engine been rebuilt or modified? What is its current compression, leakdown, and other vital statistics?
In short, a 350 engine can be very good, but it's not inherently good or bad without more information.