How can you tell if your motor is a 305 or 350.1991 caprice classic?

The easiest way to tell if your 1991 Caprice Classic has a 305 or a 350 engine is to check the engine block casting number. This number is usually found on a flat surface of the block, often near the front on the passenger side (right side in the US). It's a series of numbers and letters.

You'll need to either:

* Look it up yourself: Use a flashlight and look carefully for the casting number. Then, search online for a Chevrolet engine casting number database. Many websites dedicated to Chevy engines allow you to input the casting number and will tell you the engine displacement (cubic inches, which translates directly to 305 or 350).

* Consult a mechanic: A mechanic will be able to quickly identify the engine size.

* Check the vehicle identification number (VIN): While the VIN *can* provide some clues, it's less reliable than the casting number for definitively identifying the engine type. Decoding the VIN will tell you the engine *code*, but this code might not be as precise.

Other less reliable methods:

* Visual inspection: While a 350 is generally physically larger, it's not a foolproof method. Modifications and different intake manifolds can make it hard to tell visually.

* Looking at the valve covers: While some valve covers might have markings, this isn't a guaranteed way to identify the engine size.

The casting number is the most reliable and accurate way to determine if you have a 305 or 350 in your 1991 Caprice Classic.