I'd just like to add a note to the responses that have already been made. There is a question regarding resistor or non-resister type plugs. Remember, when these motors were new they came with copper core ignition wires and a screw on resistor (brown bakelite housing--or the later type with a metal shield as on early B21/23 motors). If you have resistor wires or plugs you don't need the screw-on type as well-- or -- conversely -- if you have non-resistor plugs--you'll need a screw-on resistors or resistor type wires. Personally I prefer NGK plugs after working at Honda where the method to set carb float height is to use the external adjustment to flood the engine then back off a set amount. Even after flooding, the motors restarted without problems. -- Dave

Start with the resistor version (consideration for other drivers nearby, in case you have no radio) of the stock heat range in Bosch, Beru, Autolite or NGK plain copper type. Many have the opinion to avoid Champion brand. After some running, pull the plugs and examine the colour of the tips;
-> Light to medium tan or beige is perfect.
-> Very clean, recheck a few hundred miles later.
-> If too clean, or there is any signs of blistering, then move one heat range colder.
-> If dark brown or any shade of black... a heat range hotter.

Euro & Japanese brands: higher number is colder
US brands: higher number is hotter

The final answer will depend not so much on your "specs", but on carburetion, timing advance curve, the fuel and also your driving style.

Depends on cranking compression & how much HP your engine makes. I like NGK plugs & always use BP7HS. If your engine runs OK on low octane, then the colder BP6HS would be better.

Hello,

As Walrus and Matt already stated, both NGK BP6HS and Bosch Supers work very well. I've used both and had absolutely zero problems with either. I tried iridium plugs, and while iridiums made a huge difference in my old Nissan Sentra, I noticed no improvement when installed on the B20. I've heard many, many bad things about "crossfire" type spark plugs.

IPD has long recommended NGK BP6HS. I have used them and been happy with them.
They are also reasonable in price.
--
George Downs, Bartlesville, Heart of the USA!

of course.... every backyard hack mechanic has their opinions on spark plugs.. myself included. I like Bosch Supers for B20s. Nothing special... no platinum nothing. Just plain old copper core Bosch Supers.

I've had bad luck with *way* premature fouling with Nippendenso plugs. I won't buy them again.

At the end of the day though.. for a fresh engine like you have.. it probably really doesn't matter. I'm sure you'll hear good things about NKG, and they too would be fine I'm sure.

--
-Matt I ♥ my ♂