Plug Indexing
 

Years ago I was at a tech session hosted by a shop that maintains a lot of Porche race cars. Someone asked the owner of the shop about spark plug indexing. He said words to the effect "If you stand on a ladder so you are closer to the Sun you are probably warmer but it would you notice the difference?"
-Chris

" If you have seen a problem - state it and when and how and document it."

Tsuter,
Do we now have to footnote and reference sources when we give an opinion? Must I have at-the-ready various books by Smith, Ricardo, VanValkenberg, etc. whenever I open my mouth here?

Accept or reject opinions on this forum for what they are and who they're from. If you think something sounds like BS, you can say so. It's the internet after all. That's your/anybody's prerogative. BTW, shouldn't you also produce evidence and sources you so firmly suggest? You might find collaborating evidence of your position on the Edelbrock or Car Craft websites. I think even the two guys on the "Two Guys Garage" show found more power from this technique once upon a time.

Another BTW. When I say I read about it somewhere. I meant from a reputable (I think) source or sources; not necessarily from what Hot Rod Magazine says or from a glossy 4-color brochure. While some or even many folks might choose to invest in an assortment of spark plug washers, I'll probably pass on the add'l dyno time it takes to rotate the spark plugs searching for those last few ponies.

JMHO,
Sherwood

OK... then I reject this opinion as unfounded and baseless.

heat transfer ignition problems - a squishy washer vs an indexing washer. Jeeeez!!!

Newbs actually read some of this rubbish and as a result they park their cars in their garage and clean the heat exchangers. :eek:

Dang, you mean that I did all that cleaning for nothing?!

How often do you guys change your plugs? 101 Projects says every 10,000 miles...but they are in the business of selling parts so I cant take their word on it... I had heard previously, every 25,000-30 anyone know?

I pull mine with every oil change. If everything looks OK, replace after 10-20k depending on your faith in the plug. Copper plugs are cheap so 10k is decent.

Please bear with me here. I recently bought a lawn mower with a Honda GXV 160 engine. If I'm not mistaken, it has an aluminum head, as does the Porsche air cooled engine. My greatest fear in changing plugs in my POrsche is that I overtorque, stripping the threads in the head, aluminum being softer metal than the steel of the spark plug. The following quote from the lawn mower
engine manual: "When installing a new spark plug, tighten 1/2 turn after the spark plug seats to compress the washer. When reinstalling the original spark plug, tighten 1/8-1/4 turn after the spark plug seats to compress the washer."
My question: Considering that it's damned tough to get a torque wrench in there when changing plugs on a 911 engine, do you guys think this "rule of thumb" would work well on a 911 engine?
Wayne? Pro wrenches? Anybody? Thoughts please...
:confused:

Tip for starting plugs.
Use a piece of rubber fuel line that will fit over the end (tip) of the plug.
The fuel line allows for enough flex so you don't cross thread the plugs.
The plugs should thread in finger tight until the washer makes contact with the head.
A 3 inch extension is too short and a 6 inch extension is too long so you will need a 1 inch extension and stack together. That seems to work.
These are Craftsman sizes.

1] I use the 1/2 turn as more as a baseline.. I developed a "feel" for the washer crushing, which is easy to do. Once the new plug bottoms out it's a consistant turning "feel" for the crushing. I think that maintaining the turn helps the "feel". A reg. hand size 3/8in rachet gives more control than a full size 1/2in rachet

2] reusing a washer is not as precise.. so it's a kinda snug enough "feel" without being over tight. and reusing a washer means the job is only good enough, not a very good..

all above is IMO

Paul -- Yes, I think that's fine. (BUt haven't you been tightening those plugs since 1972?) Also, ask Gamroth -- do they torque the plugs all the time?

- Randy

There was an article about plugs in Pano a couple of months ago. The guy got a few hp by indexing. Checked on a dyno and I believe it was about 5 hp. This was in a 944 and he said Bosche silver plugs gave a small bump also.

The 3 inch extension too short and 6 inch too long. Snap on has a 4 inch extension which seems to be just right. Of course the factory tool is still the best. Snap on, and I believe S&K have a disk shaped palm ratchet which works pretty good in the confined space for the #1 plug. I always seem to turn the back of my hand black and blue getting that one out and back in. That pointy little bracket near the plug well just beats me up!

Hi:

FWIW,..I've never seen any gains on the dyno by indexing plugs on the 911: single or double ignition. We use either Bosch Copper or Silver plugs....opening the gaps (.040) makes more HP and improves idle & drivability only IF you have a suitable ignition to support those.


Paul- Randy:

Nobody here uses a torque wrench on plugs; its all done by "feel. My suggestion for anybody who is not comfortable doing that yet would be aquire a junk 911 head and practice tightening plugs until one learns what it feels like to crush a new plug washer. You would also feel what a used plug washer feels like. Both feel very different and its an aquired skill.

Its really not difficult to learn. :)

The thing about performance tuning is you have ask yourself... "Would you do 20 things that each incrementally provides 1/2 of one percent improvemment?" None of which is "easily" discernable on a dyno - even just changes in operating temp affect the dyno record from one run to the next 60 seconds apart.

So heres' my advice:

If you're the tuner for appearance - keep cleaning those heat exchangers and polish those Fuchs!!

If you're the tuner for perfomance - don't do these small things either... that way I'll keep beating you on Saturday!! :)

Anybody sand down gaskets where they protrude slightly into the manifolds??? Intakes and exhaust??
Don't do that either OK!!!

The Snap-on is $18.00
What does the factory part cost?
Thanks!!

Cold engine. Screw the plug by hand until it seats. When the crush washer is crushing, you are just right at about exactly 18 lb/ft, so it would be okay to stop any time. When the crush washer finishes crushing the torque needed to turn the plug will rise sharply. DO NOT turn the plug any more. It's as simple as that.

I saw a factory plug wrench go on ebay not long ago for over 35$...that's where I stopped bidding. Craftsman 13/16 plug wrench and a 4" extension from snap-on is a less expensive combination.

the Hazet 2505-2 is a flex length plug socket..

Another option, tho a bit $pendy...it's middle setting matches the factory wrench, a 3/8" drive ratchet plugs right in...

http://www.samstagsales.com/images/hz2505-2.jpg

Yes, the plug should spin in with only easy finger pressure. If otherwise find the problem, usually it is dirty threads. The thread chasers are also appropriate for just cleaning. Make sure it is perfectly clean. When using a thread chaser, hook your vacuum up to the exhaust outlet in the “blow” mode. Make sure it isn’t blowing dirt and position the engine where only the exhaust valve is open on that cylinder. This tends to keep junk out of the cylinder.

There is the issue of the small terminal on the threaded end of the plug. All(?) 911 plug connectors need that terminal to be in place. Some plugs don’t come with a split lock washer. All plugs should have that terminal tightened significantly. I can’t tell you how many times I have seen that terminal off and the connector just rattling on the plug.

Another related issue with sparkplug change is cleanliness. If there is muck around the plug, it will be dragged onto the threads and into the cylinder. The muck can make it difficult or impossible to spin in the plug by hand and can deposit damaging stuff in the cylinder. Additionally it can fowl the plug sufficiently so it won’t fire.

I use aerosol “brake clean,” high pressure air, a 25c wash, and more air to clean around the plugs. I only change one plug at a time so I don’t force dirt into an adjacent open hole. A light and inspection mirror is worthwhile to insure nothing is around the plug.


Best,
Grady