Attn: Pulley mods Misfire w/ plugs?

[[sky]03cobra]

Just got through installing the 2.93 pulley and had Chris Johnson due a tune on my black coupe. (BTW he picked up 15 rwhp (sae) and over 70 rwtq in the lower rpms w/ his chip and tune )The dyno numbers came out great (sae 463 rwhp) but I was having some misfires w/ the plugs at around 5500 rpms and up.
During the dyno, at these rpms, alot of u smoke (misfires) were occuring. I changed the plugs to the ngk tr6 that most everyone else had changed to. I believe that most gapped the plugs at .40, however johnson said that he thought it should be gapped around .29. He thought that the .40 was outrageous and set too high. Is it the ngk plugs? gap?

My questions are what plugs are you guys using w/ the pulley and chip change and if anyone is having any misfires up top as well.
Second ? is what is the proper gap needed.

I would appreciate any help on this matter.
thx
sky

 

[sqidd]

I gapped my plugs at .040 and have had no problems. Sometimes mis fires are caused by lein conditions. I would check the plugs first though.


sqidd

 

[[sky]03cobra]

im running a solid 12.5 to 12.8 a/f all the way through the dyno.

 

[[sky]03cobra]

bump

 

[NetworkingGuru]

Just curious, but were you having misfires before the chip?