Do i need to jumper the diagnostic box before or just go ahead and advance while its running and fully warm (without jumpering) ?You can just loosen the bolt on the distributor and rotate it CC. to advance timing a bit. You will notice the RPM will increase a bit as well. This is how to adjust timing on the 3FE and no problem with SMOG that i am aware of. Also the golden screw on the intake manifold can be adjusted slightly, check the screw setting. It should be 1/4 to 1/8th turn from fully close.