Plug gaps?

Ven302 · 08-20-2009, 07:54 AM

Way back, we found on some street supercharged cars that the "candles" seemed to be getting blown out as boost and of course rpm increased, the guys were using some plugs advertised to be "all the stuff"
some unobtanium material, 37 ground straps (get the picture) I swapped the plugs to an NGK race plug
R567X-x type of part number advised to gap at .025 and voila the lights stayed on!, Also in my Suburban
I had a local shop do a new exhaust (hate working on street stuff) they put some platinum whatsit plug at .065 gap, the truck would misfire towing on anything but a gentle acceleration (turtle). I put some non resistor autlite race plugs, 2 ranges colder and .030 side gap and the problem went away.
My point? Go at least two maybe three colder, you can find charts on how to read the strap for heat range, non resistor and keep the gap low there will be little gains in a big gap and much greater chance of misfire.

Adger Smith · 08-23-2009, 06:41 AM

Just thought I would post some links to plug reading.

http://www.empirenet.com/pkelley2/sparkplugreading.html

http://www.dragstuff.com/techarticle...ark-plugs.html

http://www.4secondsflat.com/Spark_plug_reading.html

For those that like video:

You might keep in mind the pickup clearance plays a part in the rise time of the signal going to the ignition box. Too much clearance and the pickup will read a short spike from the magnet. To little clearance and it will cause a longer dwell & confuse the signal the box sees at High RPM.

08-20-2009, 07:54 AM	#1
Ven302 Member Join Date: Feb 2005 Location: Stoney Creek Posts: 262 Likes: 41 Liked 34 Times in 7 Posts	Re: Plug gaps? Way back, we found on some street supercharged cars that the "candles" seemed to be getting blown out as boost and of course rpm increased, the guys were using some plugs advertised to be "all the stuff" some unobtanium material, 37 ground straps (get the picture) I swapped the plugs to an NGK race plug R567X-x type of part number advised to gap at .025 and voila the lights stayed on!, Also in my Suburban I had a local shop do a new exhaust (hate working on street stuff) they put some platinum whatsit plug at .065 gap, the truck would misfire towing on anything but a gentle acceleration (turtle). I put some non resistor autlite race plugs, 2 ranges colder and .030 side gap and the problem went away. My point? Go at least two maybe three colder, you can find charts on how to read the strap for heat range, non resistor and keep the gap low there will be little gains in a big gap and much greater chance of misfire.

08-23-2009, 06:41 AM	#2
Adger Smith VIP Member Join Date: Dec 2001 Location: Texarkana Ark/TX Posts: 2,446 Likes: 575 Liked 880 Times in 311 Posts	Re: Plug gaps? Just thought I would post some links to plug reading. http://www.empirenet.com/pkelley2/sparkplugreading.html http://www.dragstuff.com/techarticle...ark-plugs.html http://www.4secondsflat.com/Spark_plug_reading.html For those that like video: You might keep in mind the pickup clearance plays a part in the rise time of the signal going to the ignition box. Too much clearance and the pickup will read a short spike from the magnet. To little clearance and it will cause a longer dwell & confuse the signal the box sees at High RPM. __________________ Adger Smith (Former SS) Last edited by Adger Smith; 08-23-2009 at 06:47 AM. Reason: SP