Which Brand of Spark plug do you run??

[scottfab]

The great thing about the way this poll was set up is that you can click on the posted number of votes on any one plug and look at who uses each plug. This can be valuable should someone change what plug they use and want to check where their vote went. I noticed a few other polls were set up this way too.

[Jagdpanzer]

When I first participated in this poll back in 2008 I still had the factory AC-Delco plugs installed. Since then I've switched to NGK Iridiums. Wish I could change my vote now.

[rush91]

I just had mine changed out, and the car just hit 50,000 miles....I forgot to ask my guy what were the plugs he pulled out. I wasn't sure what I had, so went old trust route of stock Ac Delcos.

Sent from my XT1585 using Tapatalk

[indy91zr1]

so after checking somethings my car has autolite 26 plugs. Is that plug to hot for just headers,modified airbox,tune? I honestly have never heard of the 26. I am used to running ngk iridiums in everything I have owned. Would it behove me to replace them?

So I went ahead and bought some ngk vpowers per Todd P's recommendation. When I pulled all the old plugs out there were 7 autolite 26's and one ac delco. I am sure you can guess where the ac delco plug was. Car runs leaps and bounds better with the new plugs.

[Hib Halverson]

I just love old threads....

When I owned Barney, at first, I used the Denso IT20 (an iridium plug) which is about the same heat range as the originall LT5 plug the ACD FR1LS, but then, once I learned I could go colder and still run on the street with no fouling?mainly because of my hotter coils and Haibeck's good calibration, I went to the IT22 which I stuck with for the final five years I owned the car.

Even today, I still love the Denso 22 heat range.

I use it in my '04 ZO6 (IT22), in my '12 ZO6 (IT22) and in my '19 ZR1 (IVT22).

[XfireZ51]

Hib,

Do you know why the 375hp motor has a recommend of a .035? plug gap, while the 405hp motors were spec?d for .050?? Am I correct, and if so, what change made that possible?

[Karl]

https://www.corvetteforum.com/forums...-plug-gap.html

the plugs changed.

I have been doing a lot of research on the LT5 ignition system after ordering new coils and wires from DUI (screamin demon coils and live wires)

[32valvZ]

Originally Posted by XfireZ51

Hib,

Do you know why the 375hp motor has a recommend of a .035? plug gap, while the 405hp motors were spec?d for .050?? Am I correct, and if so, what change made that possible?

I run my AC Delcos at .042 I tried them at .035 and the power was down especially after the increase in air flow from Petes porting... Im not sure why that was the case, but opening up the gap to .042 made a noticeable difference in throttle response and overall power feel of the the engine. It purrrs!

[XfireZ51]

I tried Iridiums and regular copper plugs using a .045? gap. However, I found that I was getting knock retard showing up even w stock timing Installed a set of NGK BKR6E plugs gapped at ..035?, no knock counts w stock advance +3-4*.
Let me suggest that when u do install plugs on a pre-405hp motor using plugs gapped at .045?+, make sure u scan it for knock before declaring it to be OK.
It very likely could be knock you won?t notice, but occurs randomly and is picked up by your sensor.
I found the area in the 2800-3600rpm/45-60kPa to be particularly sensitive.

[32valvesftw]

NGK BKR5E plugs gapped at .042-.045, per Corey.