Ok, here's the scoop. I have an 83 gsl with an 86 6 port 13b, full Racingbeat exhaust and a sterling carb sitting on a custom intake. The ignition is all stock, with the exception of 2nd gen leading coils, but still triggered from the stock j-109 ignitor. So, with it being a 2nd gen motor, but basically 1st gen ignition, what plugs should I use? I've been running br8eq14, but I'm not sure they're doing the job. Would I be better off running a 2nd gen br7, and would my ignition system do an effective job of firing them? Or, what plugs would you recommend?

Thanks
Brian

 

if you aint racing, FC plugs are fine.

 

I've run the 2nd gen ignition like you are, and I've run it using the Transistor Trick (allows 2nd gen ignitor to run the coils, triggered by the J109). I've done it both ways using the 2nd gen plugs on the leading side. Works fine....



.

 

Thanks guys. Now I have a follow up question. Can I run br7's for leading and trailing, or do I need to run br9's on the trailing, and what would be the pro's and cons?
Thanks again.

 

the 7 and 9 are the heat range of the spark plug. 7 is hotter 9 is colder. mazda wants colder plugs in the trailing. if you drive at low engine speeds and loads, they do list hotter plugs.

if you drive harder they want you to use colder plugs. most people would rather run all 9's if anything.

 

I guess I don't fully understand the theory behind the temperature ranges of spark plugs. I was under the impression that the hotter the plug, the stronger the spark, and the better the burn.
Can someone explain the flaw in my thinking, or point me in the right direction?

 

Ok, never mind. I found this on the NGK site... http://www.ngksparkplugs.com/techinf...000&country=US
Anyone who thinks spark plugs are just for igniting fuel should read this. I'm 38 years old, and pretty mechanicaly inclined, and I just got SCHOOLED on spark plugs.
This link should be in the faq section.

 

awesome link, i was wondering this the other day. a buddy gave me some br9's he had spare, i have 2gcdfi, and i put 2 on leading and kept the stock on trailing, and man, it makes a HUGE difference in my 12a, steady idle and a deeper sound, don't know if it pulls harder but the sound makes it seem like it lol.

 

So you are saying when I change my plugs, I should go BR9 no leading, and BR8 trailing on my 12a?

 

Can't answer the question unless we know your set up?

12a or 13b, modified or stock engine, mainly highway or city driving, stock ignition or other?

You guys need to realize that for optimum performance you have to mate the plug to the entire package.

 

the 81-85 cars all use 4 of the same plug, NGK BR series (12a and 13b are different

the 86+ cars use BUR series plugs, trailing is two heat ranges colder

 

Its an 84GS 12a, completely stock, mainly city driving. I do plan on going with NKG plugs, wires, ans was looking for NKG cap and rotor.

 

i only changed to the br9's leading because i have 2gdfis and also most of the driving in town are constant speeds of 45+

 

Stay with the stock NGK BR8EQ-14

 

Thanks Doc. What is 2gdfis?

 

2 gen direct fire ignition system.

Threads can be found in the archives. :-)

 

okay, I would have never guess that?

 

https://www.rx7club.com/1st-gen-archive-71/ignition-2gcdfis-diagram-correct-502148/

https://www.rx7club.com/1st-generation-specific-1979-1985-18/easy-2nd-gen-direct-fire-install-20-minutes-243350/page9/