i have a 12a thats bridgeported and it eats spark plugs. I know that having performance mods done like i have will cause more wear on parts. The thing i dont get is that i only get like around 500 miles out of a set of plugs . Is this normal for what i have done ot my motor?

 

Two question for you.

1st is what make and model spark plug are you using?
2nd what kind of RPM does your car idle at?




John

 

i use ngk br8eq14 and my car idles at about 1200 rpms

 

Woah, I wouldn't think using the stock plugs for a stock 12a would be a good thing for a bridgeported 12a.

 

Right you are, according to Racing Beat you should be running these babies:




This spark plug is recommended for bridge or peripheral ported, turbo or non-turbo, racing rotary engine applications. Price shown is for one (1) plug.

We offer NGK Spark Plug - R6725-11.5 for high horsepower racing engines. This spark plug is NOT recommended for street use. This part number will apply to both leading and trailing spark plugs.
Part Number: 11547
Retail Price: $37.00 ea

 

At a cool $37 each, I'd Google that P/N and try to find a price that isn't marked up 400%.

 

No **** !!! sometimes, some people , money is no object. **** for $37.00 dollors each, sparks had better fly out it's ***.

 

Ported rotary:It`s nothing unusual to replace the plugs so often,i allso have to do it.

Take into consideration that he uses the car on the street.Putting in the R6725-11.5 plugs will not work well on a street driven engine.

The plugs are too cold,and will misfire at low rpm,and low load.Good luck getting a BP or PP started with plugs as cold as those.
Another fact about them,is that,if you flooded the engine once with them,you throw it away.

It has allways been one of my irritations having to use hotter plugs for driving my car on the street.

Karis

 

I use NGK B9EGV's in my 12A turbo (that's wat they are called in Europe) and indeed, they are not verynice to drive when the engine is cold. And they are expensive here (35 euro's a piece that's about 40$) But no to little wear, been using them for 10K km's now

I solved it by going Direct Fire.... now that makes a difference !

I didn't use a MSD but i went the " Jeff20B" way

No problems anymore cold driving and is easier to start !

 

thanks alot everyone i appreciate the help. It just bums me out that i now have to spend 37 bucks for plugs but hey its all worth it .

 

Like karism said you'll be banging your head against the wall if you try using those plugs for normal street use. I'd take a closer look at your mixtures as incorrect tuning can greatly reduce plug life.

 

I use B9EG's, 12a Streetport Turbo. They are a single prong motorcycle race plug. For a bridge you could probably use b9eg's or b10eg's. I get them from www.ironpony.com (local store for me ) They're about 5-6 a piece. For turbo they get gapped to .010", don't know what gap to use for n/a.

 

Cool! I'm going to try my "way" on a friend's supercharged 13B. If the weather were a bit nicer, I'd be out there working on it right now.

That supercharged engine killed its BUR7EQ (leading) plugs but the trailings (BUR9EQ) were ok. Basically, they started to misfire at idle and low load. They were also hard to start. You could literally hear one rotor start to fire and then the other would kick in a few seconds later. I bench tested these plugs and saw some sparks jumping down through the carbon on the center porcelain insulator.

The symtoms were of the engine sort of rocking side to side at idle, along with a very lumpy idle. Higher load situations seemed fine though.

I think the reason why this engine killed its plugs is because they were designed for direct fire. Trying to fire them with a cap and rotor system is just asking for trouble.

We also tried a set of new B7EMs that were just laying around. The idle improved a little, but was still really choppy. The BE7Ms hardly fit due to the shrouds around the spark plug holes. I'd need a thinwall spark plug socket if I were going to continue using them. The gap is vey small with thos plugs as well because they were originally meant for a points ignition system.

I'm going to install a set of good BUR7EQ plugs in leading and I'm not sure what I'll put in trailing yet. It doesn't really matter at this point as I'm just curious to see how it'll run with direct fire on leading.

Should I consider the B_EG plugs since this is a supercharged 13B?

 

I would think they would work good with a s/c too. But you'll need to get a thinwall plug socket to use the b_eg's. You can lightly grip the porcelin with vice grips and tighten that way, but I wouldn't suggest doing that very much, and be very careful

 

thanks for the info i will try b9eg's or b10eg's . (sigh) It seems like my problems never end. Well thanks again .

 

My friend tightened the B7EMs by hand. They were new plugs so they were clean enough to get a good finger grip when he tightened them. I had to use vice grips with rubber things on the jaws to loosen them. A little oil was able to seep past the metal gasket. I'm sure the electical contact wasn't all that great.

I threw in the good set of leading plugs with antiseize. I also threw in the old set of reusable trailing plugs. How they survived with a cap and rotor system is beyond me. Maybe the tiny trailing hole protected them?

I hope to fire this thing up soon.

 

MOST IMPORTANT:PLEASE ALLWAYS MEASURE YOUR CURRENT SPARKPLUG BEFORE TRYING A DIFFERENT TYPE!It should be measured from the gasket,to the tip of the earthelectrode.or in the case of a surface discharge: From the gasket to the end of the surface discharge area

That being said,maybe i can be of some assistance with the plugs i use


Its NGK 2 stroke Plugs ,the number is B8ES.As you can see from the number,it`s not a resistor plug.
They are not surface discharge(as the BUREQ14`s are)just normal looking ones,with a short thread,and a electrode that barelly protudes.

The allso have a colder variant of the same plug,their number B10ES.

I get good(well as good as a non race plug will provide)performance,and they dont cost an arm and a leg.The idle with them is good,and they dont faul to easilly.

At hometownstores.com they cost $22.44 for a box of 10 plugs

Hope this helps!

Jeff:Can you maybe snap a pic of the B7EM`s? I`am interested to see what they look like

Karis

 

go here man.. 5 and some change:

http://www.ngk.com/results_cross.asp...9EGV&x=40&y=12

 

Soon. I don't have access to a digital camera this week. The best I could do right now is a black and white security camera.