What's the best way to find a dead cylinder?

cruiser said

Having rough idling/driving issues. Suspect that the engine (1974 225 bone stock everything) is missing on one cylinder. So what's the best way to determine which cylinder isn't firing? How about pointing one of those fancy temperature guns at the exhaust manifold adjacent to the suspect cylinder while the engine is running. If it's cooler than the rest, this may indicate a dead cylinder. Any other ideas out there? Thanks, all!

Click to expand...

Okay guys. As promised, here's the data on my sick engine. The first six photos are the results of the leak down test on cylinders one through six. As you can see, several of the cylinders are way down from the 100 psi that was pumped in initially. The final photo is the compression values from cylinder six (top of the page) down to cylinder 1. Now I gotta decide what to do. Looks to me like a complete teardown. I do have a spare 225 engine from a 1974 Dart with only 83K miles on it. The dilemma is whether to rebuild the current engine (very expensive) of put the replacement engine in.