Hi, I just recently performed an overhaul of the ignition system and the engine sounds and shakes worse now. I can’t figure out what the problem is. See below for an overview and a link to a video. 1975 Plymouth Valiant Brougham 225 1 bbl slant six <35k miles Video: View: https://youtu.be/tfPDmDXF0dY I did the following to the ignition system: Installed new distributor cap, rotor, magnetic pickup, vacuum advance, spark plugs & wires, coil. The magnetic pickup was set at a gap of 0.008”. The spark plugs installed were NGK Iridium IX. The timing was set and is hitting 0-2 degrees advanced @ around 775 RPM. We adjusted idle RPM up and down to see the affect. Really no change in the issue close to idle speed. When you accelerate and engine RPM is greater than 1250, the shaking/noise goes away and is not exacerbated. I used a thermography gun to measure the exhaust temperatures at each cylinder. Cylinders 2-6 were about 400-450 degrees F and cylinder 1 was about 330-350 degrees F. The coolant return is at cylinder 1. I think that is why it has a lower exhaust temperature. We also checked all the spark plugs and they are firing correctly. It does not appear that a cylinder is misfiring. Why the poor noise and shaking? What do you hear? Why was it running better before and worse now? Could it possibly be a intermittent misfire? It's driving me nuts. Some thoughts & questions: 1. I only checked one gap between the reluctor & pickup, then I set it. I did not check every gap between the reluctor and pickup. If I did this and confirmed a variance, would this be an issue and/or cause? Is it better to favor a tighter clearance if needed to bring them all within spec? 2. Are Iridium spark plugs a bad idea? Should I go with something closer to OEM? 3. The ignition maintenance wouldn’t require me going into the engine tappets and setting lifts/adjusting. My uncle wants to go into it and I don't want to. The car has <35k miles. Is it possible that a tuned up ignition system will run better with the engine only after the tappets are adjusted? This is a lot of work and I just don't want to do it atm.