gundee

I think we have been through this before several times. The cylinder head needs to get pulled to see what the deal is with #4.

Been using Pertronix ignition and coil on my 240Z for about 20 years now. Works excellent.

I sent you a message.

I never knew he was moving to Spain. If he has his car in Spain now, it may be easier to find Z help than when he was in Panama.

Wires got crossed alright. In this threads software.

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I use manifold vacuum on my 240Z. Unplugged it is set at 10 degrees BTDC. When plugged in the timing jumps to 17 degrees BTDC. Perfect.

Here are the photos of a broken valve guide I was looking for. They can also be just cracked and allow alot of oil into the cylinder. A distributor will not change anything going on with yours.

Hasn't #4 plug been an issue from the start? If mine I would pull the head. Need to check the valve guides on the cylinder. On occasion (although very few) a guide have been found to be cracked right at the head. I had a E31 head with a cracked guide and the plug looked just like that. If they replaced the guides when the head was rebuilt, they can break one if not careful. Was the valve seal replacement a head off replacement or head on replacement.

I have used the pertronix ignition with 1.5 ohm coil and ballast resistor. Worked just fine. No issue.

I do not understand needing a choke on for 1 or more minutes. In that climate where you live. Use to start only if needed then shut off. If that was my car I would have a radiator shop test and recore it if necessary. I had to do that on mine. But now you can buy aluminum radiator replacements for 240Z's. It may be cheaper to buy one of those if the old one is bad. You also may have one of those old style water pumps with impellers that rot away and cannot move water anymore. You want the better type with cast impellers. Cooling systems should be in perfect shape in your climate.

Remove the choke cable from both carbs. Make sure the jets are in the fully up position. Drive it. See how everything goes. That eliminates any issues with the choke.

Yes drive it without if you want. No issue at all. I always removed mine when I autocrossed it.

It does sound like the chokes may be stuck open. This can happen if the screw for the linkage to the choke tube is too tight.

Is this just sudden in one day or a couple days?