NGK – the DAILY DATSUN

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.

Stats:

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…

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…

Sigh – “if it ain’t one thing, it’s another…”

Heard that before? We’ll let’s take this journey of the Smog Saga story together.

Last post was about having to get the Datsun 280z smogged because it’s a 1977 (and in CA, cars 1975 and prior are smog exempt!). Lo and behold the San Jose’s Smog Tech Test Only station was finally open. I was hoping Zac, the last technician who helped me out, would’ve been there, but I guess he’s gone. So, Nguyen (first name) help me out and put the Z on the machine.

Vvrrroom… vrroom.. [small chat].. i’m nervously looking at the digital gauge nearly falling out of the green passing zone. He pokes / prods.. gets under the car.

“You don’t have a legal cat”, he says.

Doh. Seriously. So i guess i know what a bagel and oj got me last time.

He mentions that CA gov passed a law recently about catalytic converters needing a special number. I quickly clamor, “But but mine’s a ’77 and they probably didn’t have numbers back then. I swear it’s all original!”. Nope, no go. Not only that, I failed out of CO spec on the actual smog test. Not by much, but still beyond the max % allowed:

CO% levels
15mph – MAX: 1.36; AVE: 0.17; MEAS: 2.03
25mph – MAX: 1.16; AVE: 0.15; MEAS: 2.66

*AVE = Average Emissions for Passing Vehicles

So as you can see, I’m just out of the range of passing 😦 Some google searching shows this is related to a few things, but probably due to running too rich (too much fuel in the mix). After a post on ClassicZCars.com forums, rcb280z pm’d me and we had a good chat about bringing those CO% levels down. His suggestion was to also check out the spark plugs for excess carbon (ah!). He swears by NGK, and lo-and-behold, most Z drivers do!

Time to get that 280z catalytic converter changed, new spark plugs, 87 gas, and head over to Smog Tech!

oh yeah.. if it ain’t one thing..it’s:

a broken alternator bracket (that’s why my car’s been squeaking!) and…

cracked EGR tube! oy…

i need a beer.

Tag: NGK

Best spark plugs for a Datsun 280z

Stats:

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″)

Smog saga…

Stats:

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″)

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″)