Datsun Roadster Forum-311s.org

Did some tune up work on my 70 SPL with a U20. Set the valve lash first. Balanced the carbs. Set timing. Replace points, rotor and condenser. Reset timing. Shut her down and replaced plugs. Then the frustration started. Hard to start, running like crap. Timing light intermittent…WTF.

Finally traced it to #1 plug - no spark…new NGK 6ES….doesn’t fire. Replace it and she runs fine. Crazy stuff…never had a bad plug out of the box before.

Lots of choice language.
Even the Dogs were hiding
Just venting here - feeling better

Your likely using a 20 the century plug in the 21st century
It may have broke the laws of physics

DYK in 2004-5 there was a big scam going , on new site YouTube showing a spark plugs with wires connected to a lite bulb that lit up ...foreign countrys would mostly get dealers part managers to send/ ship hundreds of spark plugs to Miami by using a stolen credit card . , At mine the parts mang was going to do it , I called the techline on it they stopped it .
African native folk bought that it worked . they would get all the orders then send the plugs or kit .,and run with the $$
Lots of old S plugs were gone by this method

One thing I recently noticed about these spark plugs is that you need to make sure the threaded expanders (or whatever the reverse of an insert is) that the plug wires connect to are tight. With all the heat cycling, I had 3 out of 4 of them loose. That can't be great for delivering current.

Hey Joe that’s a BP6es correct? Cause I think there is a B6Es. Probably not much difference. Protruding head vs recessed?

Yes BP6ES. I worked on the car today. Put the old plugs back in (Bosch Platinum) Set timing 16 btdc, set dwell on points, balanced carbs at idle and at speed, set mixture at speed. New air box to carb gaskets, new air filter. She was sounding good. Replaced plugs with new NGK BP6ES (whole set). Took her for a spin. She ran great!