Plug gaps?
 

The motor I'm running is the first higher than stock (12.7 to 1) compression ratio motor I've done. I've always gapped the plugs at stock specs (on my stockers) or at .050 on our hemi stocker (30 years ago).
The stock specs for my motor (2.4ltr, 4 cyl dodge) are .045. Stock compression is 9.5 to 1.
I'm presently using stock champion plugs. What should my gaps be set at?

Re: Plug gaps?
 

The gap isn't an issue but the heat range will be. Just make sure you go colder than stock. Could be quite a bit.

Re: Plug gaps?
 

Art,

I have tried everything from .035 to .070 on my Stocker with no difference either way in performance. I like the small gap, especially in forced-induction applications. In chassis dyno testing I've seen some flutter in the graphs at high rpm that I attribute to a slight misfire. It instantly goes away when we take down the plug gap.

BTW, Justin is a real nice guy.

Evan

Re: Plug gaps?
 

After talking to George Widuch, who built the engine in my Volare, he said the pendulum is swinging toward the lower gap specs. Dyno testing and on-track testing seem to bare out that theory that as long as your ignition system is up to snuff wider plug gap does not make more power. A plus to this is your plug wires will last longer and chances of a high RPM miss less likely. Jim

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.

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:

http://www.youtube.com/watch?v=fiMM2S0aADM

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.