Does anyone worry about clocking their spark plugs?

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71DodgeDemon340

71DodgeDemon340

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ive heard of doing this before but never really tried it, ive heard of people going through 10 or 12 spark plugs before they get em clocked pointing towards or at least near the valves. Does it really matter? Its a cool concept but how do you return a spark plug and say it didnt line up like the others? I would think that with the compression of the atomized fuel that a spark no matter which way the plug is facing would ignite the fuel efficiently
 
no, you can use washers to clock them but there are far more worthwhile things to do with your time...like Pokemon.
 
I tried indexing plugs on a Dart race car I had years ago and picked up zero for my efforts.
 
RustyRatRod said:
I tried indexing plugs on a Dart race car I had years ago and picked up zero for my efforts.
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Thats what its called, indexing couldn't remember the correct terminology. I figured it was hype. I tried it on my 351 in my bronco just to see how close they were out of the box and i think maybe 2 or 3 pointed towards the valves and the others were pretty much random
 
I work for the Big 3 in one of there engine testing labs. We sometimes do it. I've gone thru 75 spark plugs to find 8 that will line up in the direction we want. We do that to rule out variables. For street use? Unless your looking for hp gains to the right of the decimal point. I would not worry. Now 12 more people will chime in and tell you other wise. They are welcome to there opinion. I've been doing Dyno work for 37 years. The topic is kinda in my field.
 
Im not worried about hp to the dot, I already know the engine makes 400 horse with randomly indexed (installed without indexing them) ngk v power plugs. Just was curious of people claiming the performance difference
 
It's done more for emission testing. Not really Hp. My reason for doing this is different than yours. But the question is good and the topic does come up sometimes. Buy 8 plugs. Install them. Call it good. :)
 
All this time I thought spark plug indexing was to insure that dome pistons did not smack into the spark plugs. Maybe it is a reason in some cases, no?
 
indexing is needed in tight chambers to keep from being hit by pistons,..mostly dome tops but i got a buddy with a sb chevy with flat tops thats so tight he has to cut the tab off at the bend to keep them from closing up!
 
i have only heard about indexing from people who own chebbies...that should answer it right there
 
If the piston is gonna hit the spark plug don't ya think its going to hit a valve or two along the way.
Jeff
 
Yep, I've done it a few times! Not that hard to do really, and IMO every little bit helps! I did it on the blue car when I first built the motor, can't say it helped anything, but didn't hurt to do it! And no, I didn't have to buy a bunch of plugs to find the right ones, I just used what I had and swapped em around a little!! Why?? Because I could and no other reason!!
 
My dad had a 499 Chrysler with some high dome ross pistons. He ran like a .100 copper spacer and indexed them, otherwise the pistons would tag them just enough to close them (at idle). Piston to valve clearance was never an issue.
 
dirty white boy said:
indexing is needed in tight chambers to keep from being hit by pistons,..mostly dome tops but i got a buddy with a sb chevy with flat tops thats so tight he has to cut the tab off at the bend to keep them from closing up!
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Negative. If you need to index plugs to keep from hitting pistons, you're running the wrong plug.

The theory behind indexing plugs is is not for physical problems such as hitting the piston, but to get the gap of the plug pointing directly at the top of the piston to "unshroud" the spark from the side electrode and expose a little more spark.

It sounds good in theory, but the thing is, a spark is all that's needed. IMO, indexing plugs adds nothing because once the spark is made the combustion will begin. I don't think it matters one bit about where the electrode points.
 
RustyRatRod said:
Negative. If you need to index plugs to keep from hitting pistons, you're running the wrong plug.

The theory behind indexing plugs is is not for physical problems such as hitting the piston, but to get the gap of the plug pointing directly at the top of the piston to "unshroud" the spark from the side electrode and expose a little more spark.

It sounds good in theory, but the thing is, a spark is all that's needed. IMO, indexing plugs adds nothing because once the spark is made the combustion will begin. I don't think it matters one bit about where the electrode points.
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agree with all that to,..on my buddys chebby,..he just built it tooo tight,..ended up pulling motor apart on count of it,...was a strong sbc tho for what it was...
 
In my own opinion, if you are worried about the power you might loose by not indexing plugs then spend your time on tire pressures and alignment, because those two being right will give you better results than plugs being indexed.
As a matter of fact waxing the car makes more difference in ET's that plug indexing.
 
It is important that the plug does not protrude in the chamber, it should mount flush. The ground electrode is also rounded to eliminate the square tips.
 
KitCarlson said:
It is important that the plug does not protrude in the chamber, it should mount flush. The ground electrode is also rounded to eliminate the square tips.
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Yep, as any threaded section of the plug protruding into the cylinder can't carry off the heat like it should.
It can even cause pre ignition and pinging from being hot enough to detonate the fuel.
 
Did it on my race engines (Fords). Never saw an advantage. Waste of time for a street engine.
 
Always felt the l that shims would throw off balance in compression ratios more than any gain from indexing.

Unshrouding the spark WILL gain you power, at least on a dyno.

Solving both problems:

BRISK MULTI-SPARK PLUG | MULTI-SPARK SPARK PLUGS

I don't know well they work, though. Never tried em
 
jeffnmo said:
If the piston is gonna hit the spark plug don't ya think its going to hit a valve or two along the way.
Jeff
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Don't think the valves are open when at TDC unless you've broken something. Then indexing doesn't matter... finding a machine shop does.
 
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