There are a couple of ways to check if the distributor is 180 degrees out on a Chevy 350 small block:
1. Remove the distributor cap and inspect the position of the rotor:
- If the rotor is pointing roughly towards the number one spark plug tower on the distributor cap, it is at TDC and the distributor is installed correctly.
- If the rotor is pointing towards the number six spark plug tower (roughly opposite of the number one tower), the distributor is 180 degrees out and needs to be reinstalled 180 degrees in the opposite direction.
2. Another method is to use a timing light to check the timing marks on the crankshaft:
- Locate the timing marks on the crankshaft: The timing marks are usually a notch or a line on the crankshaft pulley or a balancer, and a pointer on the timing chain cover.
- With the timing light connected, start the engine: The timing light will flash and illuminate the timing marks as the engine is running.
- Observe the position of the timing marks when the engine is running at idle and compare them to the specifications specified in your vehicle's manual: If the timing marks line up correctly, the distributor is installed correctly. If the timing marks are off by 180 degrees, the distributor is installed incorrectly and needs to be reinstalled.
