Need some assistance with timing. I've got a '73 1.7 FI. Installed Pertronix ignitor 1847V. Car starts and runs, but will stutter and backfire a bit under load. I can tell it wants to run better with the ignitor instead of points, so I don't think the ignitor is the problem.

I "think" I am setting the timing right, but not sure. Spec is 27 BTDC at 3500. Pulley has a white mark at TDC and a red mark at 27 BTDC, which according to everything I've seen is correct.

I set the advance on my timing light to 27, unplug/cap the vacuum line and rev to 3500, then the red mark should line up in the notch, correct?

Car has newer 3 ohm coil, fuel pump, fuel lines, injectors, fuel filter, vac hoses, TPS board replaced. Valves adjusted within last 800 miles. Pulled plugs and cleaned them up. 7mm ignition wires are older, so could they be a problem? Is there a different coil I should be using with the ignitor?

I've tried moving timing to 28, 29 and 30, but still stutters. It doesn't buck as if it's a TPS problem, just stutters and backfires.

Any advice is appreciated.

If you are adjusting your timing light to 27 you should time to the white mark (tdc).
Either that or leave timing light at 0 and time to red mark.

You can’t do both. Either red mark and no advance on the gun, or white mark with advance set. My 1.8L only has the red mark and it’s set for 7.5 BTDC … so I have to do maths if I want to check full advance at 3500RPM.

Thank you both! I'll try that and report back.

I do red mark with no advance, but then my light is SO old it doesn’t have the adjustment!!