Ever see this issue with Cometic head gaskets??

[Pronto]

So I found this on the NGK site. It's a way at drill down on what plug you want. The ones in the chart Chuck posted are not resistor. Looks like the "Racing" plugs are not resistor. This a list of the NGK plugs that fit stock heads.

https://www.ngk.com/search/reverseengineer?ptid=8&p=true&specs=165272,165273,165274,165275,165298

So a non projected resistor with a colder rating for me would be a BR6FS NGK 4323. I currently run the UR6. I might switch to non projected tip to see if there is a difference for me.

 

[626gn]

So I found this on the NGK site. It's a way at drill down on what plug you want. The ones in the chart Chuck posted are not resistor. Looks like the "Racing" plugs are not resistor. This a list of the NGK plugs that fit stock heads.

https://www.ngk.com/search/reverseengineer?ptid=8&p=true&specs=165272,165273,165274,165275,165298

So a non projected resistor with a colder rating for me would be a BR6FS NGK 4323. I currently run the UR6. I might switch to non projected tip to see if there is a difference for me.

The BR6FS plug worked well for me (iron head, e85) and can be found easily at Autozone and Napa. Currently trying out the AC Delco MR43T.

 

[TIMINATOR]

A non projected nose makes the ground strap shorter and cooler,(less chance of detonation), Side gapping aids coolness of the ground strap too (because it is shortened), and also it quickens the burn because it allows the spark to be "seen" by more of an area in the chamber, thus requiring less timing. All good things to keep in mind when choosing a performance plug.
TIMINATOR

 

[Mr.Spool]

The BR6FS plug worked well for me (iron head, e85) and can be found easily at Autozone and Napa. Currently trying out the AC Delco MR43T.

The ac delco mr43t is my plug of choice for iron heads and big boost.
Been over 1000hp with that plug.
And many who I help I tell them to run them.

 

[Mr.Spool]

I am also not sure why guys want an ngk plug,
I've used them as do many of friends but... .....
The brisk plugs are the best I've seen and I've made the most power on in my n/t 109 and n/t stage 2 car.
You can run a colder plug on the street and it wont foul out because of the silver.

 

[TIMINATOR]

I have never made as much power with any NGK plug, on the track, or dyno, although I know guys having success with them. But then again, the two guys that I know that run them are die hard NGK fans, and have never even tried anything else. Mebbie they need a different tune that I have never found.
Side gapping, indexing, and plug brand are the cheapest and easiest ways to a bit more HP. I don't know why anyone wouldn't experiment with those ideas.
The MR43T plugs are prettier than most, with the nickle plating, and are easier to read. I believe the nickle coating is for noncorrosion in a marine app, and the colder range is for continous, high HP running. We just tried them in my pals N2O car, at Mr. Spools recomendation, and it seems to like them.
TIMINATOR

 

[1KWIKSIX]

I’ve been running NGK YR5 non projected tip plugs on my car . Of course it’s a lower boost (non Alky ) street driven car

 

[SCOOBY DOO]

CR43TS from my friendly GM dealer. Changed them out twice per race season for 20 years. Zero issues.

 

[Chuck Leeper]

Chuck, I'm a little confused. That chart you put up says the plugs are resistor but when I look at them on websites for sale they say non resistor. They rate them at 1 ohm. Is that enough to stop any electrical interference?

I'd be inclined to believe the mfgr info, by getting it firsthand. Most plug mfgrs have tech people. That's who I'd go to, when in doubt.
Far too often, I find inaccurate information from sellers... Like Summit for example.
Not sure 1 ohm is sufficient. but may be, when adding in the wire ohm values.
A good "ask the pro's" question....

 

[Pronto]

Chuck, see post 81.

 

[Norman C Shibley]

The ac delco mr43t is my plug of choice for iron heads and big boost.
Been over 1000hp with that plug.
And many who I help I tell them to run them.

I've been out of the loop for so long on current plug recommendations. I've always run CR42TS on 23lbs with meth and champion irons. Do you still recommend the mr43t and what gap? Thanks so much in advance.

 

[Mr.Spool]

I've been out of the loop for so long on current plug recommendations. I've always run CR42TS on 23lbs with meth and champion irons. Do you still recommend the mr43t and what gap? Thanks so much in advance.

Mr43t gapped at 24

 

[Dan SS2471]

The ac delco mr43t is my plug of choice for iron heads and big boost.
Been over 1000hp with that plug.
And many who I help I tell them to run them.

I'm running the NGK YR5s based on input but am experiencing a bit of sputter on the tip in - light throttle. When I briefly had the AR133s installed, it was smoother. They're non-resistor so I swapped in the YR5s to avoid issues with the stock ECM. That aside, I read this and picked up a set of MR43Ts just now (Advanced only had 4...have to pick up the other 2 tomorrow). Question is, do you consider 24-26PSI and an approximated 630HP a fit for them and also a tight gap at .24? Appreciate it.

 

[dynoman]

Question is, do you consider 24-26PSI

Mr Spool will ask you if you are just breaking it in at that level . That's what he said to me when I said I was at 30-31 psi................. He's run double that on those plugs . I'm sure he will respond though !!

 

[Mr.Spool]

This^^^^^^^^^^

 

[Mr.Spool]

I'm running the NGK YR5s based on input but am experiencing a bit of sputter on the tip in - light throttle. When I briefly had the AR133s installed, it was smoother. They're non-resistor so I swapped in the YR5s to avoid issues with the stock ECM. That aside, I read this and picked up a set of MR43Ts just now (Advanced only had 4...have to pick up the other 2 tomorrow). Question is, do you consider 24-26PSI and an approximated 630HP a fit for them and also a tight gap at .24? Appreciate it.

That plug is the only plug i run in irons.
They are cheap and non projectile and dont foul out in street driving and I have run diesel boost numbers on them
From 30psi stock turbo combos to 50+psi big turbo combos the plug works
All with a stock ignition and coil module.

 

[Dan SS2471]

Thanks, guys.

 

[gnfanatic]

Hey guys, car is running. I also installed the E-dash for my xfi, it is nice to see live data. The afr is 7.5 at cold idle and the car is running rough til it warms up. Hoping to get it tuned in about a month so far no leaks and no smoke like before.