I remember seeing a thread about this in either Adv. or FI, but the poster had a big boost setup.

I just swapped my Autolite 104s for some 103s--my 2nd time and it took less than 2 1/2 hours, all from the top and without removing anything!

I noticed something interesting. The gaps on the 104s seemed to have closed about .002" on almost all the plugs (except for #2, which was about .001" WIDER than I set it).

I had been running nitrous, anywhere from 75 up to 150 for a few times, but mostly 100 shots. I have an Accel 300+ ignition and coil.

Any ideas what would cause the gap to close? I had set them at .040" when I put them in and they were almost all around .038-.039" in only about 8-9 months or so... I'm setting the new ones at .038", trying to hunt down a slight stumble at idle, tip-in, and knock retard on the juice.

 

Detonation will close gaps.

 

I agree. It's probably detonation.

 

OK, that would certainly make sense since I was getting knock on the nitrous.

Thanks, guys!