Fuel fire and air 

You have the fuel checked off, it's good. You have the air filter housing off so no restrictions there. You should focus on the fire or electrical now that all 6 are black and sooty. It could be a loose wire since all of the sudden the spark plugs went black.

Did it not start running bad all at once? It should have after looking at the before plugs and the newest pictures.

Have a good weekend.

From what we have seen that wasn’t the problem. Someone suggested you check the chokes that was all. You’re going to need a meter and start testing the ignition system and go from there IMO. If number 4 is fouling concentrate on that. #4 plug wire. #4 contact inside and outside the cap etc. etc.

I know nothing about pertronix but is it possible the coil wire to the dizzy cap is seated good and tight

3 hours ago, siteunseen said:

There's all kinds of testing you can do, you've missed some and some have missed you but you have gone ahead and shot the parts cannon at it for no reason.

There's ways to test the spark at the plug and check resistance at the coil.

"We" would like nothing other than your problems resolved and ending this, FYI.

It may be as simple as the distributor cap and worn rotor button?

If a new single point distributor will solve this fouling will this one fit and work with my 1972 240z manual transmission?

Post a link to the distributor not a screen shot

He has tested leads, caps plugs, pretty much everything. The only thing he hasn't done is remove the pertronix from the system.

You could just replace the dizzy and see if that fixes the problem. If not then plug wires and coil last...

Jalex's NGK plug wires are almost new. I like the idea of replacing the dizzy. Will the coil he's currently using (snort) be OK with the new dizzy?

Lets see if i can explain this better. Step by step:

1. Crank the engine with the choke pulled.

2. Let the choke on for 1 to 2 mins.

3. Drive for 20 mins

4. Suddenly get trapped in traffic jam and temperature needle raises to 3/4

5. Rpm needle starts to go up and down between 900 to 1000 rpm

6. Once traffic is clearing i accelerate and engine starts misfiring with hesitation simulating coughing.

This is the best written explanation i can give.

Edited August 18, 2024Aug 18 by jalexquijano

 A temporary solution is to turn off the engine when you're not moving. Yes. you may have to restart it to move 20' before you turn it off again but I used this method for years in hot weather and traffic jams. It prevented overheating. Idling builds engine heat. BTW, what type of fan are you using?

2 hours ago, Mark Maras said:

Jalex's NGK plug wires are almost new. I like the idea of replacing the dizzy. Will the coil he's currently using (snort) be OK with the new dizzy?

I agree, although new doesn't always mean good. I would start with the dizzy. I think if the coil was the problem then it would be more even across all the cylinders. Although the lastest fouling could indicate a broader problem.

Are you able to get good quality fuel there? I know mine runs much better on non ethanol premium. Fuel quality has gone downhill since the 70s

Gasoline 95 

21 hours ago, Patcon said:

Post a link to the distributor not a screen shot

He has tested leads, caps plugs, pretty much everything. The only thing he hasn't done is remove the pertronix from the system.

You could just replace the dizzy and see if that fixes the problem. If not then plug wires and coil last...

https://www.ebay.com/itm/365041263498?_nkw=datsun+240z+distributor&itmmeta=01J5KJ4EANEBQJ75J87RVQ36KT&hash=item54fe27a38a:g:ZUUAAOSwgDRkuoxW&itmprp=enc%3AAQAJAAAA8HoV3kP08IDx%2BKZ9MfhVJKnVJtqAmYWy3zOonVsGkjVw0awl81HSJzk0MGHS0Waj5%2BR4hG2eW6tAhWl4xTim%2Fq1obu6j2vFOm%2Firwx96gWlyUXNqE9AvQWdMViJudjl8sJ%2FXkTJtVZxZ3gg5Nfe6TBy7V%2FqE%2Bm6npqMYASMPn03%2Fmi8JllLr%2BicVotUns%2FdjJnW4z78DIeVOIf%2By37NVrYIbyyjIAJN8J1o9LRQOWUdp0NPyCGIbDg7u1Hhvw66oodgNbME5vm1I4lNYKqkiUZCupcDny1CDeqO9uxvdwHMjrp2krPPdK%2FHLM4WybmJLMw%3D%3D|tkp%3ABFBMsuWR8qxk