spark plug indexing

[MOPARCHAS]

Ok guys give your opinion am I waisting my time indexing my plugs or does it matter

[cuda367]

I spent a couple hours or so duing it on the cuda. No change so I don't bother anymore.

[gthomas]

I bought a Jacobs ignition and was not too impressed with it because I didn't feel that it was much of improvement for the money, until I indexed my plugs, it was like night and day. That sold me on indexing. Also when using a good ignition system and platinum plugs I gap the plugs a little wider than recommended because the platinum plugs don't get the wear the older plugs used to get.

[Billydelrio]

I use the clock method to index my plugs. I just screw and torque to 35 ftlbs. The mathematical probability of having the electrodes where I want them is 1/12 per cylinder, which is better than my 1/1000 chance of winning a race. So I don't bother indexing the plugs. (ha ha)

If I were a little more serious about "HUNTING HORSEPOWER", then I would index them.

Billy

[dschumers]

I have never seen anyone do a back-to-back on a dyno and I think it would be very interesting. I have alot of friends who race 'class' cars who index the plugs, and they have told me that it makes very little difference, but they need every .001 they can get. The only thing that I have heard that makes any real sense is that it keeps plugs from fouling by keeping the gap exposed to the combustion flame.

[Fluid]

Lots of people repeat the old saw, "ya gotta index your plugs man!" One unanswered question is, indexed to what? If indexing makes any difference at all, then the direction the electrodes are pointed makes a difference too. Indexing them all the 'wrong way' could give a reduction in performance!

If you index them all towards the intake, then the position of the electrodes will be different in different cylinders. If they were all indexed at 3 o'clock, then half would be pointed towards the intake valve and half towards the exhaust! This cannot be right. From the above it can be inferred that anyone who indexes them all in the same clock position doesn't know what the purpose of indexing is, and any "improvement" in power they claim is bogus - a figment of their imagination.

Racing motorcycles often index and the owners 'claim' it is important, but is it really? I too would like to see any definative testing program to answer that question. Indexing may well help, or it may just be a "feel good" technique that wastes time better spent on something else.

[etracer]

I've always indexed my plugs so the gap faces the intake valve. I also cut the electrode halfway back to unshroud the spark. I recenly read in Drag Review(?)some motors like the plug to face the exhaust valve. I don't have any definitive proof that it helps,but....it surely can't hurt. This year I'm running Stock Eliminator so every little bit helps.

http://www.geocities.com/icm3459/

[68ChargerRT]

I've done it on my (almost) stock 440 and it made no difference.
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[shannon]

I read in a slugstang book that it made 6 hp difference on a 400 hp 302. The plugs were indexed tward the exaust valve.

340 party

[Fluid]

I read in a slugstang book that it made 6 hp difference on a 400 hp 302.

That may be true, but that doesn't mean that indexing would give a 1% increase on all engines....it may give more on others, or less. A 400 hp 5.0 has far different chamber flow and burn dynamics than a swirlport Mopar.

[wyoming 64savoy]

The combustion chamber will affect the results from indexing plugs, I've done it and not noticed any worthwhile difference, but I'm a bracket race, so .001's aren't that important to me. From the stock class racers I know on a BB Mopar some improvement can be had from pointing toward exhaust valve, most don't mess with it since they run enough under index to qualify, and thats their major concern.

[Billydelrio]

Fluid
When I mentioned the "Clock Method" in my previous post, I was trying to imply that I do not index my spark plugs. But, I do have a 1 in 12 chance of having each plug properly indexed at whatever the best indexing would be.
On some engines, poly 318 for example, you can index all the plugs to the same clock number as the chambers are all the same.

The big question still remains, where is the best place to index to. It is my opinion that the answer to that question deponds upon the flow and swirl characteristics of the cylinder (as Fluid mentioned) and unless each person experiments with his/her own engine, that question will not be answered.

I think surface gap plugs will solve the question of where to index!

Billy

[70gtx]

talked to machinist who dynoed my 440.he say not much difference un less its a dome piston motor than not a whole lot but every hp counts in the end.

[70gtx]

also he says between 10 and two o'clock.

[HOLESHOT]

my 2 cents is that while I have tried a number of engines,none changed that I could tell by indexing,how ever I have noted that plug gaps and brand of plugs were noted to help more.

[71 scamp]

I gained nothing from it.

[MOPARCHAS]

I want to thanks everyone that replied to this subject I don't no that spark plug indexing realy helps but I have noticed that the plugs stay cleaner longer when they are put in at 12 o clock