Re: 1972 240z won't start
Just got out of the same problem actually. Set #1 cylinder at TDC (#6 should also be at TDC), double check #1 cylinder intake and exhaust valves. They should be closed. Double check #6 intake and exhaust valves. #6 intake should just be opening and #6 exhaust should just be closing. Check distributor drive spindle - the half moon should be facing forward towards the radiator with the spindle at 11:25. When replacing the cap and rotor, see that it is right on #1 plug. Check the spark plug gap. If you're using an electronic distributor (Hitachi DH88 something,...can't remember the number exactly), the spark plug gap is .044 not .041. .041 will still make the engine fire but it won't be smooth and perfect. Replace the distributor cap and rotor with new ones. A hairline crack (sometimes not visible to the naked eye) with cause puttering, backfire and engine miss (been there, found that!). Double check continuity of all 7 high tension wires with a multimeter. Wiggle them around to ensure there are no intermittent readings or faltering current. The firing order that Kevin Taylor provided was the right one. If you have carbs, pre-adjust the throttle (not sure of the right term) adjusting nut below the carbs at 3 full turns (they have to be even), don't worry about the idle yet (just make sure it got some). Once the engine started and warmed up to normal, you can set the perfect timing with a timing light and then adjust idle and synch your carbs and throttle linkages.
Stock L24/dual SUs