Hey guys what are the best spark plugs to buy and at what gap?

 

OEM stock gap I think .32?

 

.032

 

Lol I meant that

 

OEM. They are Ac Delco 41-108 and make sure they're gapped at .32

 

NGK ILTR5D or AC Delco 41108, same plug rebranded.

Gap on them should be .035-.036 out of the box, I wouldn't bother messing with it as the owners manual calls for 0.035 and the service manual calls for 0.030-0.035.

 

And all the experience on this site says .032

 

Just my 2˘ and GM's standards, had 3 guys chime in with a gap size without citing anything before me. I don't recall if I even checked the gap on my plugs last time I tossed new ones in the car.

 

I guess it all depends on the tune, but I'm running .032 iirc

 

I have 50k on my current plugs and will try to take measurements when they come out of the car.

 

I run .028 just cause

 

I prefer a little smaller gap also. I just put in .029" gap. Smaller has little down side for power (WOT) conditions. It might affect idle and part throttle efficiency a little (compared to say .035-.040"). Meaning emissions could go up a little (but hardly measurable, mainly just theoretical).

So a little too small equals no real down side for what we really care about (high load or WOT), but a little too big is a pain in the but with slight misfire or spark blow out at high boost, leaving one wondering what is going on.

Plus you can get a few more miles out of the plugs since gap increases slightly with mileage. I could get more than double the life out of copper plugs on my old platform by gapping down to 0.024" to start (compared to those that started at 0.032"). Now I would not expect double from Iridium plugs gapped that low, but maybe a bit more if you start with 0.028" to start compared to certainly .035" to start with.

 

Having seen them get smaller over time due to carbon on other cars.

I wouldn't go too small. But generally yeah they get wider.

 

That must have been one cold plug! Carbon deposits should burn off if you have the correct heat range plug for the application. Carbon fouling is usually too cold a plug, or running way to rich for an extended period of time.

 

so basically a Trifecta tune...

I kid I kid.

Kinda

 

I have been running 0.028 but I'll be going back to 0.035 after my head build which includes ZZP's high voltage coil packs.

 

So the coil packs just allow you to open the gap, get more spark?

Do they actually produce more power? Or just smoothness?

 

its all related. the more power to the spark, the more you can open the gap because there is enough power behind it to "jump" further. The longer the spark, the better the burn. the better the burn the better the "smoothness". etc.

bigger gap= theoretical better mileage, power, and overall "smoothness/quality of the running engine.

That's why you always want to run the biggest gap possible without getting blowout.

 

What he ^ said