Best spark plugs for a Datsun 280z

What ARE the best spark plugs for the Datsun 280z?

ClassicZCars forum, Haynes service manual, and many others swear by only one: NGK’s copper core spark plug.

During this smog-crisis I’m having, I did a switch up to help pass smog (more on that later), and after a bit of research,  sometimes the plain, simple and cheap solutions work best. This is certainly the case.

The best spark plugs I’ve experienced for a 280z are the NGK 7734 (BR5ES) or the  NGK 7634 (BR5ES-11).

Daily-Datsun-Sparkplugs (3)


But why? Why not platinum? iridium? Hell, if kryptonian-nuclear-nitrous-laced-ium spark plug was real and can wallup Superman, I’d think it would have been the best for that straight L6 engine, right? Nope. Save the precious metals for wedding rings. Platinum et al. may fire hotter, but you’ll notice right away that the contact point is much much smaller. Our 70’s era engines aren’t perfect, so there’s certainly going to be carbon build up over time – so less surface area, easier for carbon to build up and over.


NGK BR5ES (7734) / BR5ES-11 (7634)
B – Thread Size / Hex Size: 14 mm / 13/16″ (20.8 mm)
R – Resistor
Heat Rating Numbers : 5
ES – Firing End Construction: Standard 3/4″ Thread Reach (2.5 mm) Center Electrode
11 – Spark GAP: 1.1 mm (.044″)

The Nissan / Datsun factory service manual says the spark gap should be between .039″ – .043″ (.028″ – .031″ for Canada). So though they’re somewhat pre-gapped at the factory, you should still buy a gap gauge to measure and adjust, checking for variability.


Here’s what the plugs looked like, taking them out of the 280z after 2 years…

Daily-Datsun-Sparkplugs (1)

Ooo not good. So I replaced each one, and let her rip.

Woohoo! More power, instantly. From the moment I pressed the throttle (and i’m usually kind of a turtle), I notice the difference right away!

I’ll definitely be monitoring the spark plugs more closely, and be adding it to a biennial or yearly maintenance routine since the NGK 7734 (BR5ES) or NGK 7634 (BR5ES-11) are cheap enough.

Now on to that cat…

2 Replies to “Best spark plugs for a Datsun 280z”

  1. Hey Justin it’s Bryan, just a recommendation that helped me, I was told by a former nissan/datsun tech to switch to ngk BP5ES-11, he advised I get the projected tip, which is the P, and the non resistor plugs because the plug wires are already resistor

    1. Hey Bryan! Great to finally meet you. Thanks for the info – i’ll be sure to switch over to those next. It’ll be interesting to note the difference between them!

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