To cold spark plug?

[Jimmy Jakobsson]

Hi! What can be said about these spark plugs, i think they are to cold and wrong for my engine, it is ngk 7 non projected tip. The engine 493 cui stroker scr 10,04:1, edelbrock e street 84cc heads, xe275hl (231/237@050) camshaft, the engine runs great but slight misses on idle, the engine have about 400 miles on it since cam break in.

 

[beanhead]

Yes. Look at the threads, there should be coloring from heat on about the first three, and it looks like you only have coloring on the top one. No need to 'test' with all 8, I would put 6's on one side and 5's on the other, run it a while, then see which one gives you the best indication. Even though more soot collects from too cold a plug, it appears your idle is also way too rich...

 

[68Moparmaniac]

AF meter will be the best way to check your mix brother, the rest is guessing...IMO

 

[Jimmy Jakobsson]

Yes. Look at the threads, there should be coloring from heat on about the first three, and it looks like you only have coloring on the top one. No need to 'test' with all 8, I would put 6's on one side and 5's on the other, run it a while, then see which one gives you the best indication. Even though more soot collects from too cold a plug, it appears your idle is also way too rich...

Thank you, i will try to go hotter on the plugs and lean out the idle

 

[Jimmy Jakobsson]

AF meter will be the best way to check your mix brother, the rest is guessing...IMO

Thanks actually i installed a AEM A/F wideband meter and it works for about 20 minutes, now when i start the car it " do its thing" go back and forth and than show about 14 for a few seconds and than bottoms out at lean and stays there no matter how i drive and only shows - - - three lines. Is the lambda broken already? Its properly installed at about 2 a clock at the pipe. The pipes are not leaking and the weld not show any light through so i believe its not leaking and i believe it must be one hell of a leak to show lean like that or like this one only three - - -

 

[RJRENTON]

Out of curiosity, why are you using a non-projected nose plug? The NGK series with the "V" center electrode configuration is a great design which promotes good flame front development. A projected nose plug would allow a slightly hotter plug to resist low speed/RPM fouling yet prevent high speed/RPM overheating or preignition. The projected nose is "charge cooled" by the incoming fuel mix. NGK also uses copper type center electrodes which offer a much broader heat range. In addition, NGK offeres several different electrode alloys and configurations for good versatility. It also appears that your application needs 3/4" reach plugs. Autolite has many different styles and types to consider. Champion also offers several configurations to consider as well. Again, fuel ratios, cam shaft configurations and ignition advance characteristics affect plug coloring.
BOB RENTON

 

[Jimmy Jakobsson]

Out of curiosity, why are you using a non-projected nose plug? The NGK series with the "V" center electrode configuration is a great design which promotes good flame front development. A projected nose plug would allow a slightly hotter plug to resist low speed/RPM fouling yet prevent high speed/RPM overheating or preignition. The projected nose is "charge cooled" by the incoming fuel mix. NGK also uses copper type center electrodes which offer a much broader heat range. In addition, NGK offeres several different electrode alloys and configurations for good versatility. It also appears that your application needs 3/4" reach plugs. Autolite has many different styles and types to consider. Champion also offers several configurations to consider as well. Again, fuel ratios, cam shaft configurations and ignition advance characteristics affect plug coloring.
BOB RENTON

Thank you for your answer i just wanted to try the non projected plugs and see hows it go with it, i have understand they prevent detonation but also that they mostly are used in boost applications. I have not heard any pinging with the hotter ngk 6 projected tip i drive before this and not see any signs of it when i look at the tops of the pistons with a endoscope through the spark plug hole but i just wanted to try these non projected style out but i will switch back to ngk 6 projected tip again and see how they look after some driving, the engine does have smoother idle with them.

 

[Frank Mopar]

The hotter the plug the more they project into the cylinder.

 

[RJRENTON]

The hotter the plug the more they project into the cylinder.

Not necessarily.....it depends on the design. Usually hotter plugs have a longer insulator, but it grows longer inside the shell, up to the sealing land that the insulator is anchored to. The overall length of the center electrode is longer but inside the shell. Heat range is also a function of electrode diameter, insulator diameter and density and insulator length. NGK's web site shows, in cross section, spark plug internal construction parameters as well as complete reference to all alphanumeric reference information.
BOB RENTON