I've always put the BP6ES plugs in my cars.  I did the ZX distributor swap on my 240, '79 ZX dizzy and coil and just widened the gap.

Now I'm bored and go to NGK's website to see what's recommended for the '79 ZX.  They say BPR5ES so I went to a couple of parts stores online and they say the same thing and have them on the shelves, the 6s have to be "shipped to home, non stocking item"

Please advise!!! 

Seriously, anybody have any advice/experience for this?

 

The BPR5's are a hotter, resistor plug.

If you are happy with the way the current plugs look when you have examined them, why rock the boat ...

5's run hotter and will burn off deposits more so than 6's. They will look a little cleaner.... that's all the increased temperature will do.

If you have oil getting into the cylinder then hotter is better to reduce fouling.

Hotter plugs may cause pre-ignition if the conditions are right so you have to be careful of how hot you select.

It is generally better to go with the colder plug on engines that are in good order..... but there is very little difference between 5 & 6 to worry about.

 

 

Edited January 4, 20178 yr by 240260280

FYI: http://www.hotrod.com/articles/spark-plugs-tips/

I think I will try the 5s and now maybe I understand the reason they changed, thank you Blue. 

"  However, with today’s cleaner-burning oxygenated unleaded gas, an equivalent engine needs to run plugs about 1-2 heat ranges hotter than originally specified (many plug manufacturers have revised their catalogs accordingly).

1 hour ago, siteunseen said:

"  However, with today’s cleaner-burning oxygenated unleaded gas, an equivalent engine needs to run plugs about 1-2 heat ranges hotter than originally specified (many plug manufacturers have revised their catalogs accordingly).

This is counter-intuitive.  Not seeing the logic.  Is that from atlanticz.ca?

From the link in post four.

Counter intuitive is an attorney wearing a pony tail. No matter how good they are the judge still looks down on them.

Edited - too many words.  I'm not sure the guy that wrote the article really knows what he's talking about.  But you can always go back.

Are you "outing" Blue as 4-6-8?  

Edited January 5, 20178 yr by Zed Head

 

I think of that every time I type Blue,  my favorite is when they tie the block to his "soft porn" body part for impregnating females with a longer rope and chunk it off the roof.

FYI, he outed himself about a week ago.  I believe he's trying to beat my high "reputation score" & doing a damn fine run up. 

 

You have to be careful when you read catalogs. You don't select plugs based on what year of Dizzy is in your car. You select plug heat range based on compression, cylinder running temps, type of emissions controls and other engine variables. Engine modifications such as higher CR longer duration cams also have to be taken into consideration.

Note: The 280ZX NA motors had really low compression ratios and specific emissions controls, which required a hotter spark plug than other years. Mainly because  the cylinder temps were lower. Those particular engines ran a lot of EGR for emissions purposes. EGR reduces combustion temps and tends to foul plugs, especially when you run a large amount of it. My question is... Are you running a completely bone stock 1979 280ZX engine in your 1972 Z? I suspect not.....

I'd stick with the NGK 6 range if the engine is running clean. If it's pig rich and burning oil. then yes, 5's might be needed. But I've never seen a healthy L series engine require anything hotter than a 6. NGK...except maybe way up North. NGK  5 plugs in a healthy Z motor definitely run the risk of pre-ignition under load or on the Freeway.

With a Matchbox dizzy you should be also using a resistor plug. The non resistor plugs were only recommended for low output ignitions such as points and 1975/76 Trignition boxes which are weak sauce. A resistor plug actually causes a higher flash over point to be created, which aids in cleaning plugs. But you need a decent amount of amperage to support them. The ZX Match box dizzy has lots of power.

Use a projected tip as well. That will place the spark tip slightly deeper into the combustion chamber and will produce a better flame kernel.  In a clean running L series with 9.0 to 10.5 CR and a Matchbox dizzy I would run a BPR6ES or BPR6EY. Those come pre-gapped at .8mm ( .031" ) , projected tip, resistor. The S suffix is a standard tip. Y is a V-groove design.

You could also run a BPR6ES-11 or BPR6EY-11. These are the 1.1mm ( .042" ) gapped version of the previous plugs. The Matchbox dizzy has more than enough grunt to fire the larger gap. A larger gap generally produces a bigger spark kernel ( a good thing ). Only problem is sometimes the longevity of Cap and Rotor is sacrificed with the larger gap plugs. 

Always use a good Spiral Core spark plug lead such as MSD or NGK. NGK spiral core leads are very high quality.

Edit: NGK's plug site recommends a BPR6ES plug for a stock 1971 240z. That should tell you something right there.

Edited January 5, 20178 yr by Chickenman

I know this is a old post but ignition systems, plugs and plug wires are never out of vogue when discussing early Z's.  I recently converted from the points to the crane PS 91 coil with the xr3000s module.  Some minor engine mods were as follows:  030 overbore, dished pistons, stage two cam with racing hardware and lifters from Robello racing ( slightly aggressive), very aggressive port/polish, Kamerai adjustable cam sprocket, trick flow cam degree adjustment, msd plug wires.

SU's stay but did add electric fuel pump and Abarth free flow NOS muffler.  ( did convert to 5 speed trans ( close ratio)

I went to the NGK V power BSPR6EY11 plugs with a 44 gap.  Car runs great but my friend who did the engine work says I could go to 46-48.  Any comments on the gap recommendation.  I am still running the stock distributor sans the points.  It does however have brass contacts vs. the stock aluminum.

1972 Z  06/72 mfg date

 

Thanks

Edited May 14, 20177 yr by Marine240z
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