The Performance Six Engine I'm researching has Indexed spark plugs, the Electrodes are marked on the wrenchable part. How have you heard this is supposed to be important?. Powerband
I cant see where it would make any diffrence.The gas explodes when it sparks no matter which way it sparks.
From what I've read, it's an old racer's trick. Lining up the open side of the electrode toward the center of the combustion chamber is supposed to create a more even burn, therefore a better power stroke. I've never been quick enough to actually check to see if it works Flatman
According to some tuners I have talked to, it is good for 1 hp per index. 8 free hp, what's not to love?
Indexing plugs is critical on some high compression motors, I had a BBC once that would hit the rounded side of the ground strap if they were not 'indexed'. Other than that, I do not think that most of us would see signifigant gains in HP by indexing plugs.....there are a lot of other areas where HP can be found before we have to worry about this..lol.
A few of the guys who raced "stockers" used to do this back in "the day". It was a pain in the ass (hadta use shims under the plugs to get the correct alignment), and I never saw any real value. It seemed to me to be sort of an "act of desperation" for stock class racers who were pretty limited in what they could do to their motors. I think it was mostly something to do in the pits to burn off nervous energy (something we all had in abundance when we were in our early 20's - LOL) while you were waiting to be called to the line. I never knew of anyone using the technique in any of the "hot car" classes. It may be of some small advantage (although, I'm a bit skeptical of the supposed 8 HP improvement). Guess it can't hurt, but personally, I wouldn't take the time to screw with it for a street driver.
everytime I try to index, I bail at the last minute because to do so, I'd have have mismatched torque. One plug would be "wound" too tight and another possibly too "loose". The last thing I want to do is strip a plug socket.
special washers are available for this: http://www.jegs.com/webapp/wcs/stor...atalogId=10002&storeId=10001&categoryId=18455
Fair enough, it would depend on the build of an engine and the total system which would put constraints on hp numbers. Some studies have shown 1%-2% of total engine power can be lost through poor spark plug direction. When set up in a defined class for racing, every little bit helps, I imagine.
The way this is done in the field is about so: A block of metal is threaded to take a plug; Some plugs are marked for electrode position, and tried for fit until a plug that indexes properly is found for each hole (racers buy their plugs by the case...). The plugs are then screwed into the metal plate, and a line drawn upon it to indicate the electrode position for each cylinder. Henceforth, new plugs can be screwed into the plate and assigned to a cylinder by which mark they align with. If they don't align well enough to satisfy the tuner, they can be tried again with spacer washers. Certainly harmless, possibly beneficial, keeps people off the street and out of trouble...
hey, thanks, I never knew those existed, but I suppose I never looked either. $15, huh? I wonder if I bought those, indexed my straight 6, it would make it feel more like an 8. Thanks again for the info.
I used to do it in my racer. Once you get the washers right per cylinder most of the plugs went in the same with that washer. The "trick" was to point the opening at the exhaust valve. Anything within a few degrees is ok. I still do it on my sleds. Anything that has potential benefit to ignition is worth doing. I see less fouling in the sleds and saw better consistancy in the bracket racer.
gains are alot more noticible on nitrous or alcohol. gains are not as significant as say...port and polish work. the easiest way to handle indexing has already been covered-buy lots of plugs, sort through them till you find one that lines up. THIS WILL MAKE NO NOTICIBLE DIFFERENCE ON A STREET CAR.
On your street car you won't notice a difference. When I was building race bikes I'd dyno them indexed and not indexed, it only made an appreciable difference on full tilt motors and was only part of the whole engine set-up. It's easy to do with the right set of washers and I'd bother for a race vehicle but not a street.
I just want to throw in an irritant... If you shim a plug out in the hole just to get the electrode to line up a certain way, doesn't that increase the head CC volume dropping the compresion ratio and therefore drop the power on that cylinder? I would guess this nit-picky with the plugs would be done on an engine that had the heads meticulously CC'd, right?
Merely pointing the gap into the cylinder does not get you anywhere other than killing a few hours of the day. Indexing is done on a dyno so you know which way to point the gap. After you get the index you have to make sure you transfer it to each plug in the correct spot, each plug in the engine will be different. Washers need to be used sparingly and many many plugs may be tossed to get a correct index in the specific cylinder. If you have to index because they hit, you have the wrong reach plug installed or the piston is not trimmed correctly.
Up until last weekend we held 8 records for 8 classes that we run at El Mirage. Russ Eyres took one of 'em and got into the "Dirty Twos". Good for Russ, he worked hard for that one. Was it indexing plugs that got all of those records? I rather doubt it. Is all part of a system. If you're gonna race, race. Do everything you know how to prevail. I'm not talking about throwing money at stuff or cheating. I'm talking about attention to detail. Think about missing out on a record by a few hundredths of a mile per hour at Bonneville when all other conditions are present to pull it off. If I've got my druthers........... On the street, not so much. Wayno
I am using a short plug and my pistons have a indention in the domes for the plug. I am not 100 percent sure that the piston would hit the plug,it is close, but I am not going to risk it!
elmo ridge is right..when you are racing , you do EVRYTHING you can do to get an edge on the other guys i did too....back 20 years ago when that was what i was doing on the street it probabilly doesn't make a difference
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