stobrien

85 gls-se with header, no cat, race beat sytem to the back. K&N intake.
Which of the 2 plugs above would be best for my application. I am have always used 8,s on my 12a,s but have never owned a 13b, or should I mix and match trailing and leading?

coldy13

I'd stick with the 8's. 9's are a bit colder and should be used on a streetport motor. But for a stock port the 8's should be right.

Elysian

i thought it just had to do with the strength of ur spark? like dlidfis guys usually run the same plugs as 2nd gens, as well as 2GCDFIS uses 2nd gen plugs...

Pele

iTrader: (28)

Why would you use 9's on a SP engine? Is the combustion temp any hotter?

Jeff20B

iTrader: (13)

It's a common thing that I've heard of people doing when they have streetport, but it's also based on the old info out of the RB catalogue. I've never done it. My streetport 13B has BR8EQ-14 in all four holes. When it comes time to get new plugs, I'll get some BUR7EQ for the leading holes which is a little hotter if we just go by the heat range number. There is no way I'd use BUR9EQ in a leading hole.

Direct fire ignition allows us to use the 2nd gen plugs in our older engines without the possibility of misfire as can happen with a cap and rotor ignition.

My bro's stock GSL-SE had an old set of BR9EQ-14s which we replaced with 8s. It seemed to work fine.

wwilliam54

if you do alot of long trips 9's would last better

but other than that, go with 8

Brianhsval

Go with the 2nd gen direct fire conversion, put 7's in the bottom and 8's in the top. Thanks to Jeff when I ran with it like this it seemed to have beeter take of response than it did with 9's all the way around, or 7 in the bottom and 9 in the top.

Jeff20B

iTrader: (13)

Cool!

YapaKanichi

I run br9eix on my SP

Jeff20B

iTrader: (13)

My recent testing and Brianhsval's comments have reinforced the idea that the spark plugs need to match the ignition system. Since leading is direct fire, BUR7EQ should be used. Since trailing is still through the cap 'n rotor, BR8EQ-14 should be used.

Brianhsval, when you say 9 in the trailing holes wasn't as good as 8, are you talking about the GSL-SE BR9EQ-14? Since it's trailing it probably doesn't matter too horribly much. Besides, the BR8EQ-14 plugs are still probably easier to find although Schuck's recently stopped stocking them. They can still be special ordered though.

YapaKanichi

hey are my plugs good for my application? Racing Beat suggest using them.

Jeff20B

iTrader: (13)

How old is your information? The BUR7EQ plugs were too new to be included in the '71-'85 RB catalogue was it last updated in '85 or '86. In it, they recommend all sorts of old style plugs that predate the BUR7EQ. They said the B8EV and BR8EQ-14 didn't differ in engine power production according to their testing. I personally wouldn't use the B8EV for different reasons.

More recently, Jim Mederer himself said not to use the BUR7EQ on a cap and rotor system because it requires more power to fire reliably without misfiring. Then I told him about some of my direct fire exploits and he simply said to try them. Luckily we have direct fire to take advantage of this newer 'surface discharge' design.

I'm not sure what your 'br9eix' plugs look like off the top of my head, but I bet they were originally intended for a motorcycle or something. Do they just have one ground electrode like the B8EV? How is the shell length? Do you need a thinwall spark plug socket?

YapaKanichi

nah, they're like a regular spark plug, alittle thinner looking, but they're the iridium plugs. So good I blew up my old muffler. I gotta get a wav. of my new muffler it sounds completely different.

Jeff20B

iTrader: (13)

Heh, all that afterfiring wasn't kind to your muffler.