Spark plug gap

[crookedriverranchman]

Hello everyone, I am new to this group and know that I can find the right answer,. I have a 2000 k2500 Chevy Silverado 7.4 vortec and am replacing the plugs. She has about 94,000 miles and looks like the original plugs are in her. I bought a set of Ac delco double platinum plugs and am wondering if there is some kind of agreement on the gap. I have looked at several different forums and no one can agree on the gap. Some say .060, some say .040-.050 before I put all of these in I would love some help in deciding in the best gap. Thanks in advance for any recommendations.

 

[Frank Enstein]

On a stock engine the factory gap is fine. I recommend spiral core spark plug wires. I like the Taylor Thundervolt 8.2 wires.

Do not pry on the firing tips as they will break off. Only bend the side wire to change the gap.

If you are looking for better power or fuel economy a larger gap may help but it may require higher powered ignition.

Some engines are insensitive to plug gap. Others will respond in a big way.

Consider indexing the plugs. Having the side electrode on top may help performance too. There are washers to help index the plugs.

 

[JOHNGAAA1]

.060

 

[Schurkey]

7.4 vortec and am replacing the plugs... ...I bought a set of Ac delco double platinum plugs and am wondering if there is some kind of agreement on the gap. I have looked at several different forums and no one can agree on the gap. Some say .060, some say .040-.050

I'm not thrilled with gaps larger than .045. That said, I'm thinking stock gap is .060 and the ignition system should handle that without problem.

The gap you use will depend on the plugs you buy. If the plugs are designed for a .060 gap, crushing the side electrode to achieve a .040 gap is not a good idea. Plugs designed for a .040 gap will be similarly unhappy if you stretch the side electrode open to .060.

As said--fine-wire center electrode plugs need great finesse to change the gaps. You can bend the center electrode, or break the Platinum or Iridium or Kryptonite speck off the electrode(s) in the process of altering the gap. If the gaps are all uniform, and close to spec...leave 'em alone.

If the gaps are way off of spec...you bought counterfeit plugs. Don't feel bad--I did when I bought from a dirtbag in Texas, selling on Amazon.

what do you mean by indexing the plugs?

A "hot-rod" technique that uses shims between plug and cylinder head, so that the side electrode of the plug faces a certain way in the combustion chamber. Shims of various thicknesses are sold so that the plug tightens-up with the electrode pointed wherever you think is best.

Supposedly, a way to gain 2--10 horsepower in an otherwise-finely-tuned engine.

I'd call it "worthless" on a stock engine, and on most mild-performance engines. But I've been wrong before.
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Stef's Fabrication 30500 B&B Performance Spark Plug Indexing Shims | Summit Racing

Free Shipping - B&B Performance Spark Plug Indexing Shims with qualifying orders of $109. Shop Spark Plug Indexing Washers at Summit Racing.

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[crookedriverranchman]

Thank you all for the great tips, all in all this has been a great truck and with only 90,000 miles on her I want to stretch her life as long as possible. We will be buying a camp trailer next year when we finally retire so am getting her as ready as possible. I did buy the double platinum AC delco from napa.

 

[PlayingWithTBI]

A "hot-rod" technique that uses shims between plug and cylinder head, so that the side electrode of the plug faces a certain way in the combustion chamber. Shims of various thicknesses are sold so that the plug tightens-up with the electrode pointed wherever you think is best.

Supposedly, a way to gain 2--10 horsepower in an otherwise-finely-tuned engine.

And the reason some head manufacturers make them with slanted plug holes pointing under the exhaust valve.

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