Which Brand of Spark plug do you run??

[HADI-ZR1]

Please Let us know what plug you run, and your opinon about it.
most Spark plugs in the poll have part number for Zr-1.

What I use now is Torgue Master Spark plug, it is the same as BRISK PREMIUM LGS. I use them more than 1 year with NO fail and the lt5 become more aggressive than before and still...
the picture is here:
http://briskusa.com/images/BR_LGS.jpg

[jonszr1]

i am currently using the e3 in the callaway and the new bosch ultimate in the 90

[Aurora40]

NGK iridiums

[HADI-ZR1]

My next test would be Brisk DOR15LGS!
here the email i got from BriskUSA and i post it here for info. exchange!

With nitrous we recommend heat range Brisk 14The measured gap is about 2.5 mm. However LGS style plug is a semi-surface discharge plug that requires significantly less energy to jump the gap than standard plug. This plug works well in applications where recommended standard gap is .8mm and up. The stock ZR1 use DOR15LGS, if modified or nitrous you should use DOR14LGS or DOR14LGS-T ( a version with reduced gap for high compression, forced induction or nitrous applications).
Best regards,
Chris

http://www.briskusa.com/images/GMHighTechMagazine.pdf

[Pete]

I use AC Delco plain jane resistor plug i think it's 61-402 gaped at .035

I'm not a big believer in maricle plugs or snake oils,unless somebody has real proof any of the snake oil,plugs make more power i will stick with AC Delco's.

Pete

[Z Factor]

NGK iridiums

Same here

:cheers:

[Paul Workman]

I was trying to run down an intermittent stumbling problem when I replaced my plugs with the platinum AC/Delcos. The stumbling turned out not to be the plugs, however.

That said, I'm happy with the performance. But, I don't think I would go "platinum" again. My research since then leads me to question the value of the longer life touted by platinum in my specific application (read: street driven and no full-out racing to speak of).

Plugs in a street driven car degenerate in a more or less linear fashion - in 3 phases, if you will: At first they are good, then so-so, and then there is that phase where they work but really need to be replaced.

The difference between the standard plugs and the platinum plugs is the length of those three phases...and of course the initial cost. So, I've concluded that the standard plugs are cheap enough and they're easy enough to replace on the LT5 that I can afford to replace them regularly enough to keep the plugs in that "new" phase. (That said, platinum plugs cost about the same as a tank of gas. So, replacing them every 5+ years...is no biggie either way, I recon.)

Different applications dictate different plugs. Those that autocross or drag race a lot would have different ideas than those like me, I'm sure.

[RedSled]

AC-Delcos

- Keith

[tomtom72]

I'm sure that there are better plugs than the GM replacement for the FR2LS plugs. I just feel that buying the regular 61-402's @ .35", and throwing them out every winter isn't killing me cost wise. I would even believe that the 402's aren't really a direct replacement for the 2ls's.....but the 402's seem to work real well for 5k miles at least.

[White Bullet]

AC for me. They are easy enough to change out if need be.:cheers:

[ZR1Vette]

AC Delco here too

[kirkstingray]

AC Delco forever. Kirk

[zr1don]

NGK FR5GP, just installed replaced AC FR2LS's.

[ZRapid-1]

AC Delco 61-402 with a 0.035 inch gap.
Haven't seen any test results which show there is a better choice.

I plan to change them every few years.
This is in contrast to new cars with platinum plugs and their 100,000 miles change interval.

[FastMatt]

What Plug are the NOS guys running? I'm thinking of going to the colder NGK TR6. Anybody use those, does the car suffer N/A when the NOS is off?

[efnfast]

Off the top of my head, NGK, one temp range colder, iridium tipped, gapped at 50, as instructed by Marc.

[scottfab]

AC/Delco (dbl platinum) and still look great after 10yrs.
I pull one every oil change to take a peak.

[C4Fanatic]

Can't believe that no one is running the Accel Silver Tip, bargain priced at $72 EACH!

[John Boothby]

AC Delco Platinum 41-800

[C4Fanatic]

AC Delco Platinum 41-800

That's the one I'm going to try in mine John

[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.

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[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/c4-zr-1-discussion/238624-spark-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]

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.

[Hib Halverson]

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 don't know what change made that possible.



As to why the bigger gap, I bet Behan probably knows for sure, but I bet it was to improve idle stability and idle emissions.

[Hib Halverson]

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


Sheesh that's a hot spark plug. I wonder why he recommends that?

[Matt B]

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 read that 405 engines used better plugs from the factory which were less prone to wear than what was used in early engines. So they could be gapped already wider without loss of lifespan.
Not sure if I remember correctly with that but it sort of makes sense.

Can anyone confirm? Or am I wrong?

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[ImpalaDave]

Just installed Denso IT20TT plugs as per a recommendation by Marc I found on the forums. Gap 0.045". I was aiming for an NGK 6 heat range equivalent plug as I'm mostly street driving with an occasional pull. They're an iridium/platinum electrode plug - supposedly ideal for wasted spark ignitions. This was my first plug change since acquiring my Z this year - the AC Delco 41-963's were crusty (due to moisture?) and had worn to about 0.053" except one, which was about 0.037" (dropped before install?). Runs noticeably better now.

Plug 8 was much easier to get at than I expected - below is the combination of tools I used to get at the plug. The aluminum welding wire was used to separate the plug socket from the short extension, magnet used to remove the socket and extensions from the hole.

[max76]

Bosch FR7DC+ 0.9gap

I'm in Italy

[Hib Halverson]

Just installed Denso IT20TT plugs as per a recommendation by Marc I found on the forums. Gap 0.045". (snip).

How times change...

Starting maybe 20 years ago, on the ZR-1 Net mail list and later on this forum, I evangelized the advantages of the Denso IT20, hotter coils and opening up the plug gaps to .045-.050. While I convinced a few folks of the Denso 20 heat range's merits, at the time, not a lot of folks tried that.

Now, even Marc is suggesting the IT20TT which is basically the same plug but with two, rather than just one Iridium tip.

After I had the late Jim Van Dorn's Automasters, build me a 500-hp "Street Skinner" engine, I went yet another range colder to the IT22. That worked very well for just about any driving I did, except for chassis dyno development, when I would install a set of IT24s.

Today, I still use the Denso Iridium Power IT22 in an LS6, an LS7 and the 2G LT5. Denso, at least so far, does not make an IT22TT or I'd use that.

And, yes, the 405-hp engines used a double platinum tipped, conical seat spark plug whereas the 375-hp engines used a conventional-tipped, flat seat spark plug. Interestingly, the plug for most production engines was an AC FR2LS which was a very late change. Originally, the plug was going to be the AC FR1LS, which for the time, was a very cold plug, but some issues with "pre-delivery fouling" with very early 1990 cars, had GM going one range hotter to solve that problem. The AC 1 heat range was about the same as the NGK 6 and Denso 20 heat ranges.

Another interesting tidbit was that all early LT5 heads manufactured by Brimal were machined such that the flat seats for use with spark plugs having sealing washers could be converted to conical seats for plugs with "tapered seats" simply by installing the taper seat plugs with a one-time "over-torque" procedure which cold-formed the conical seats in the head allowing use of taper seat plugs which in most cases provide a more reliable and durable compression seal.

Ain't these look at how it was back in the early days of the C4 ZR-1 hobby just too much freakin' fun?:thumbsup:

[XfireZ51]

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

I am using same only gapped at .035?. I did try the
NGK BKR5E-11 which come gapped at .044? but motor seems to operate smoother at .035?. My LT5 has had porting by Pete along w his Stage 2 cams.
FYI, no knock retard to speak of.

[lfalzarano]

De so IT20TT gapped at .45


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