i have a 90 civic crank pulley on a 92 engine and i think the timing marks are off but im not sure. well i was wondering what efffect advancing and retarding makes on hc, co and nox. should i just make it all the way retarded or is it gonna make on of those things go up ??? thanks in advance

 

Ignition timing has the biggest effect on NOX. Advancing the timing increases the cylinder pressure and raises NOX. Over advanced ignition timing can shoot NOX through the roof. Ignition timing also effects HC and CO, but to a lesser degree. I would not recommend retarding the ignition timing all the way, a few degrees retarded should be sufficient. If all of your emission control devices are intact and your engine is well maintained, your vehicle should pass the emisions test.