MSD instruction manual says..

"The gap of the plugs can be opened in .005 increments, then tested until the best performance is obtained"

So what are indexing washers??? Or are you just recommending to torque that plug on down until you get the right angle.... squishy be dammed?? That's OK too but you better be careful. You get maybe 20-40 degrees or so. :)

Oh ... and I know why Bosch, NGK, and Champion recommend never to use two.... do you??

Bosch also would never say its ok to use a diode with an N75 valve either!!! You say... what's a diode!!!

That's what performance tuning is all about. and it isn't OEM! :)

Well, just finished putting in new plugs. Not that bad. The Porsche tool helped greatly. The car runs great now.

I think mine is cross threaded!
 

My car may be why this topic has drawn so much interest. I went to change my plugs Thursday for the first time since I bought it and found plug # 6?? to not want to come out easily. I have done about 3 revolutions and it still is feeling pretty tight. I think the previous owners mechanic crosstreaded it in. I have left it 3 revolutions loose (or not so loose) and hooked up the spark plug wire. It is running fine. I was afraid to keep turning it until I'm at a shop in case I can't get the new one back in. Anyone else had this occur on a 911? Any words of wisdom?

Yes. It happens once in a while. Maybe a case of the steel spark plug and the aluminum threads in intimate contact due to electrolysis. Go to the anti-seize thread and see what they say.

Good move not going any further until you can get prof. help. Hope it's not too serious.

Sherwood

Seems like as a good a time as any to revive the topic of plug indexing! The best explanation I've seen of plug indexing is on the Automedia web page:

Indexing Spark Plugs.

"Generally speaking, the idea of indexing is to position the spark plug so that its gap is facing the center of the cylinder, angled slightly toward the exhaust valve—the most common arrangement. (Some engines work better with other gap locations.) This is important because, as the piston approaches TDC, the air/fuel charge is being compressed. The charge or "mixture" is being forced toward the area of the spark plug—and normally, the exhaust valve. The true speed of this force inside the combustion chamber is extremely fast. Some experts speculate that it surpasses supersonic speeds.

The shape of the combustion chamber, the shape of the piston dome, the type of ignition system, and a myriad of other variables influence the "location" of the spark plug in the cylinder head. Because of this, the spark generated from the plug should be in a "position" to create the best possible flame front. Looking at a typical side-gap spark plug, you'll note that the electrode can actually block the flame process. On the other hand, if the electrode gap faces the on-rushing air/fuel charge, it stands a much better chance of igniting a flame front ...

Real-world power gains vary. Some engines or combinations respond differently than others. In fact, all engines will pick up power, but some gains will be more dramatic than others.

In the end, it can't hurt to index the spark plugs. This can contribute to superior engine efficiency and improved economy."

P.S. +1 Old member to revive the thread! http://www.pelicanparts.com/support/smileys/wat6.gif

well put, David!

Best,

DSHEPP806