best type? - I agree, to a point. The original AC Delco plug for a 2004 Sierra was either copper core, or at best a platinum. Going with the AC ...

I agree, to a point. The original AC Delco plug for a 2004 Sierra was either copper core, or at best a platinum. Going with the AC Delco Irridium core would not be a fundamental "change" like going to an E3. It would just be an upgrade to the latest technology. I love the irridium plugs.

By the way, if you do use irridium (in any brand) do not try to gap them. They should come pre-gapped. It's very easy to damage the electrode if you try to gap them.

EKinMN wrote:The original AC Delco plug for a 2004 Sierra was either copper core, or at best a platinum.

GM truck engines have had platinum spark plugs since OBD II (1995). The old 41-932.

I also went with iridium and would recommend them. And only copper spark plugs need to be gapped, don't gap platinum or iridium.

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OK. I am officially concerned now.

I just changed out my spark plugs on my 00' 5.3 with the stocker irridiums. I read in my Haynes manual that 04' and later needs to have a .040 gap, which is what the plugs came set @. For my older truck it says that the gap needs to be set @ .060 of an inch. So I set every one of them to that.

Is what I did incorrect???

Thankyou!

Marty

Setting the gap can be difficult, because the plugs are easily damaged. Apparently, you did it right, without issue. How does it run?

Pretty smooth as far as I can tell. I can't do a "from before" comparo as I threw them into the new engine I just dropped in. I only drove her a few miles to get home. The idle didn't catch my eye so it should be fine I suppose. I would have noticed sitting @ those redlights.

OH! Also, I threw in some new injectors while I was @ it. The new injectors are 2 hole while the old ones were 4 hole! The truck is running. Should I be concerned??? I suppose I should start a new thread on that Q though. lol

They were supposed to be the stock replacement. AC Delco.

Ya know....if it ain't broke, don't fix it. I don't know much about injectors, but it sounds like ya did it all right.

you cant use a regular gaper on irridium plugs. nothing may touch the irridium electrode. The way to gap them is with a pair of pliers. As long as it runs good your all set. injestors only need to be replaced when they go bad.