My valve timing is correct but my ignition timing needs more advancment but my distributor is at it's limit. It needs about a quarter inch more advancment. Do I have to replace somthing? Distributor, o2 sensor, ecu? I tryed to set the ignition timing correctly with service check jumped. Some times I can set the timing correctly when cold but ones engine is warm to hot it goes to retard. The vacume check says late ignition timing. About my car : 1993 Civic DX 3Door Automatic Stock Engine = D15B7 witch came with a PM8 8 valve Civic CX head. -Engine rebuilt with new belts, hoses, pumps. Head = Rebuilt and Machined PM3-6 16valve witch I swaped recently since I needed a 16 valve head Vehicle Condition = Rebuild the engine, installed the machined 16valve head, new oem injectors, good fuel pump, good main relay, code readable ECU, new oem battery. Replaced the rotor and cap of the distributor. Only things I have not replaced on the engine are the Distributor, Igniter, Coil, and spark plug wires. I recently replaced the midus muffler since it was rusted out and causing back pressure. Possibly over heating my catalytic converter and o2 sensor. My conclusion = 1. May take it to local honda dealer for $100 to $200 to find solution. 2. Buy new distributor with spark plug wires. 3. Buy new o2 sensor. 4. Buy correct head or camshaft for my year and model. Currently have a PM3-6 head but engine comes with a PM9 Other thoughts = 1. Valve timing with crank shaft are lined up for TDC along with distributor marks are at TDC, and rotor is pointing to No.1 spark plug wire. 2. Have tryed setting valve timing retarded with good results for Ignition timing but pour engine performance and the valve timing looked off a tooth. 3. Have checked and rechecked. 4. Currently getting pour gas mileage. So what do you master techs think? hehe. -if you guys know this one I can answer several post that people have with the same problem. I need my car to get to college so any quick help is apreciated. _-=UPDATED_-=I may move this problem to new post called "Help... I can't set idle and need more rpm" since I need proper idle to set timing first hehe I learned to check idle first befor finding problems with ignition timing, Yup that is the result of this post. I think I am almost done with solution to this rough idle and acceleration problem.