Spark Plug Choices... lets debate.
 

Okay guys, there are tons of plugs that we can use in our cars... and everyone has their opinion on what is best.

Currently i run BR8EQ14's leading and trailing w/ DLIDFIS. and they always end up carbon fouled, so i've been toying with the idea of going hotter to some BR7EQ14's. However, i've been reading a lot about people using the 2nd gen plugs in a 12a and having much luck, i think they're BUR7EQ or something like that? Racing Beat reccomends a BR8/7EIX for performance applications.

now a couple of questions, why are we running resistor plugs? And should i run different plugs leading and trailing? Is there any plug cheaper than the awfully dear $8/per BR8EQ14's? Why are some of our plugs the 4 prong type, and why are some of them the 1 prong type?

basically, i know this is a hotly debated topic of discussion, and there are a lof of you guys out there that have played around with lots of different plugs, and have very informed opinions, i'm sure a lot of people have problems with spark plug choice, so lets make a reference thread about spark plugs.

My setup, which is probably similar to most of the modded 1st gens around here is a stockport 12a, with a pretty rich running Dellorto, and a racing beat exhaust system. I also have DLIDFIS, w/ the trailing running through the leading area of the dizzy.

so let'er rip.

I just ordered plugs and wires for my streetported 12a. A well known rotary mechanic in Jersey told me to buy spark plug NGK B7EM all around (approx $4.20 each). I'm waiting for them in the mail.

I've tried many NGK plug models that have been recommended to me, but have never really noticed any difference, only the smoothness of having new plugs. I have not tried anything other than NGK. Maybe next set will be non-NGK.

On a side note, the rotary mechanic also told me to order the $17 NGK wires. I've had the same 8mm Morosso wires for the past 4 years in the car, so I'm gonna give the NGK wires a try.

autolite=devil

i've tried the BR8EQ14 as well as the FC setup plugs, can't tell any difference. (i'm running the FC direct fire btw)

What plugs should I use? I got a 13B 4 port using 70's plates and -se rotor housings with a large streetport and holley.. Just wondering. Currently using -se ngk plugs

What I'm about to say is my opinion. Spark plugs should match the ignition system. For DLIDFIS or any other leading direct fire setup, I think FC plugs (BUR7EQ) should be used. BR8EQ-14 should be used in trailing since it's still going through the cap and rotor. Each ignition circuit matches the plugs.

So far I've installed FC leading plugs in two engines with a new DLIDFIS install, and have had great results. When the time comes to get new plugs for my other engines with DLIDFIS and BR8EQ-14 in all four holes, I'll replace the leadings with BUR7EQ. I'll also determine whether the trailing plugs actually need replacing. Some of you may have noticed that the trailing plugs tend to show less wear, whether it be direct fire or stock FB style ignition. Yeah, it depends on the wear and general condition of the plug.

jutny, you're running too rich. Direct fire's second leading spark per rotor face tends to makes engines run a little leaner since more AF mixture burns. Your induction system needs a little adjusting, me thinks. Racing Beat recommends B8EV for through-the-cap performance engines. I found this out from Jim Meaderer himself. I told him I was going to use BUR7EQ plugs and he told me they require more voltage because they are a 'surface discharge' type of plug, and they could misfire if sparked through the cap. Then I told him I'm also upgrading to a direct fire ignition system, and he said to go ahead and try it. I did, and it worked beautifully. :)

So those B8EV plugs are just a way to get more spark into your incoming AF mixture without upgrading anything else in the ignition system. I see no point in using them with DLIDFIS. Besides, a thinwall spark plug socket is required if installing them on any '79 or later engine (or possibly before then since I don't know when the semi-circle shrouds started appearing at the spark plug holes).

I too have a dellorto that used to run horribly rich with a stock FB ignition system in an REPU. Then I upgraded it to DLIDFIS and it improved quite a bit.

DoceA, B7EM plugs are for an old, weak points style ignition system. They have two ground electrodes and a very small gap. Yuck. Even BR7ETs would probably be better (three electrodes and a slightly wider gap). If I were you, I'd run from that rotary shop, unless you had a bone-stock twin dizzy 12A or something. At least you got them for a decent price.

I'll stick with NGK. Yeah, Autolites are the devil. I'd never save a couple bucks per plug just to use them. Besides, I can find NGKs (1st and 2nd gen) for 4-5 bucks locally.

FBDrifter, I think the FC plugs in leading should last longer. That's why I'm going to switch all mine over when they're due for a 'tune up' (lol, what a misnomer).

gonzz, I have four four port 13Bs from the '70s and '80s (3B and R5 castings), and all have DLIDFIS with BR8EQ-14 in all four holes except for the rebuild I just dropped into my REPU a couple weeks ago. It's the first to get FC plugs in the leading holes. It fires up really quickly for being a rebuild. Infact, the FB plugs that were in it during the first few minutes of break-in were misfiring something-awful. It would take several crank attemps to get it to fire to life. Then I threw in the FC leading plugs, and it fired up in three seconds and has been starting great ever since. The FB plugs were faulty to begin with, but they looked fine so I used them. Heh, I was embarassed and relieved at the same time when I found out it was just the plugs.

jeff20b: so if i run BUR7EQ leading, should i stick with BR8EQ14 trailing or go to B8EV for the trailing? ( i have a lathe, so i can make a thin-wall socket if i need to). Should i go to 7's on the trailing too?

also, i still dont know why we're using resistor plugs...

i ripped off my carb today to check all the jets, to figure out why she runs so rich, and as per gruntled.com, i have the proper jetting everywhere. So i put it back together, and strapped it back on, and used the mixture screws to lean her out to the point where she was rolling real bad and then backed off so she'd run "smooth"... and she still wants to make you cry with the exhaust. I just dont get it, she runs well though, i cant really drive her far from the farmhouse, as i have no plates on it... nor rear brakes, but its not running badly, allthough i havent DRIVEN her in almost 8 months, so i could just be forgetting what it was like. BTW: when i switched to DLIDFIS it got a lot better, but it still runs rich at the tailpipe, no doubt about that... now wether thats normal for a rotary or not, is beyond my knowledge....

i need new plugs, cause the 4 BR8EQ14's in there are all pretty black.

*sigh*

BR8EIX's all around for me.

So tell me again while going to directfire set-ups why should I move the trailing wires to the leading position on the cap?

look at your cap and rotor while reading this... the trailing part (top of the rotor) requires that the spark jumps twice to get at the plug wire (from the coil input terminal, into the rotor, then out to the plug wire), wheras the leading part only requires one jump (because the carbon button always makes contact w/ the rotor)

-Kurt

jutny, stick with BR8EQ-14 in trailing.

If I remember my Racing Beat catalogue correctly, Mazda recomended B8EV before NGK came out with BR8EQ-14. Then when RB tested both plugs, they didn't see a difference in performance. I'd stay with the BR8EQ-14 for many reasons.

1)no need for a special thin wall socket
2)cheaper
3)easier to find (gotta go to a motorcycle shop or order the B8EV from RB instead of simply getting BR8EQ-14 from the local auto parts store)
4)Mazda worked with NGK to come up with the BR8EQ-14 specifically for the 1st gen's electronic ignition system.

I see no reason to screw up what so many Mazda and NGK engineers worked on. Yeah, keep them in trailing since they don't misfire if hooked through the cap and rotor like FC plugs possibly would.

BUR7EQ seem to be right for leading with direct fire. The BUR9EQ would be too cold. There is (or was) such a thing as BUR8EQ (T) and BUR6EQ (L), but they were used in JC Cosmos where the engines were lazed about in luxury cars, thus needing hotter plugs to burn off all the carbon. My 20B came with L7 and T9 and was full of carbon because the plugs were simply too cold for the driving style. Heh, I've got new L7s in it, but this time the driving style will match the plugs. :)

No debate in my 80 I use BR8ET's.. Why? Because never had problems with them.. If I'm do something that may goof up the plugs (like cleaning carbon out of the engine) I put in cheap set of Autolite AR2594's. Why because the cost about a buck fifty each..

allright, so i'll run:

Leading: BUR7EQ
Trailing: BR8EQ-14

does NGK make a BR7EQ-14? i know autolite makes their version of it, but Napa dosent list NGK for one.

Did the '80 come stock with BR8ETs? It's possible I suppose. The '80 is the only 7 that had electronic ignition with ignitors on the fender and semi-firing trailing. Let's not forget the thermal reactor, heat exchanger, rich carb etc.

jutny, yes they do. I've seen a couple empty boxes once, but never saw the plugs themselves. I guess you could try ordering them from NGK or something.

Racing Beat Sells BR10EIX for all high performance applications... they work great for me... neone think of a reason y not?

here's my contribution ...

Plug Thread 1

Plug Thread 2

let me preface by saying this might differ according to region, i don't know. however, i get mine at the local Advanced Auto Parts. i think they're like $4 each, too. :) i can get the 8's and 9's. if they don't have them stocked in the store, then they usually get them in by 6 PM that same day. the 7's, however, i have to order from Mazdatrix or Racing Beat.

I'd have to order the BR9EQ-14s, but the 8s are always there at Schuck's. I've never tried to order any 7s.

Here's a little update. Schuck's no longer normally stocks BR8EQ-14s. They're special order now. :( This means there are going to be a lot of 1st gens with those crappy autolite 2526 (or whatever the part number is) running around now. Morons.

Locally in Las Vegas plugs run 8 bucks a plug. Can I order them cheaper with shipping?

Probably. I couldn't tell you where though.

Since there was some mention of B7EM plugs in this thread, and karism was interested in seeing what they looked like, I took a picture of one. Enjoy.

Man, check out that tiny gap!
https://www.rx7club.com/forum/attach...chmentid=72016

well i'm happy to report that my BUR7EQ's leading havent fouled yet :p: and the car is running great now that i got the idle mixture all fixed up, i think i need to pull out a little fuel pressure though, cause i'm only getting 21-22mpg HWY, and i used to get 25, so i must be a little rich on the top end.

That's cool. How is your tail pipe? Try wiping some of the carbon off and see how long it takes to build up again, if at all.

In a "non" stock engine with DFLISDIS i recommend B9EGV's