I was advise that besides tuning both carbs (still getting spark plugs 4 and 5 black), if i replaced the following parts, the idle could get smoother below 3,000 RPM: 

 

K & N E-2910 Air Filter

 

http://www.knfilters.com/search/product.aspx?prod=E-2910

 

 

Magnecor Spark plug wire set:

 

http://whiteheadperformance.com/products/magnecor-competition-kv85-8-5mm-spark-plug-wires-6524-datsun-240z-260z-280z-280zx-l24-l26-l28/

 

 

My car has a petronix ignitor and 3.0 ohms petronix coil.

 

 

If upgrading these parts will give me a smoother idle and less hesitation, i will make my order. Otherwise, if it is useless, i wont bother! Please advise!

 

 

I don't have either on my '71 and it idles fine and has no noticeable hesitation. Was that advice given by someone selling K&N filters and race car spark plug wires or by someone who has them on their car. I think I'd look for other causes of the issues you mention.

Dennis

thanks. its a friend of mine who has a carburetor engine Porsche and advised to upgrade to K N Filter and Magnecor Spark Plug WIres. I have the stock nissan filter and ngk blue wires. Maybe i should try and  just lean the mixture a Little bit on the rear carburetor.

Edited September 26, 20159 yr by jalexquijano

Getting the mixture correct has a huge impact on running smoothness and noise. Spend time on the getting the basics right and not adding new parts. It is quite suspicious that only 4 and 5 are black, 6 should be the same as they are all fed by the carb mixture.

Like your friend, I also have a Porsche and have K&N filters on the carbs. However, on my Z, I have the stock air filter element and blue wires like you use. I think that your idea of adjusting the carbs to resolve the issues is best.

Dennis