I currently have a 4# lower and chip but stock plugs. I just got some NGK TR6 plugs and I need to know what to gap them at. I need to know because I'll be putting them in tommarrow. All my mods are in my sig.

Thanks

 

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You could go a little closer to 0.38 if you wanted. Depends on how aggressive your A/F is. Bigger spark means better (but hotter) burn.

I run IT20's at 0.38.

 

I have an 03 Lightning and searched the Lightning forums about which spark plugs and what gap until I started to get pissed at everybody. I am in the same boat! I just installed a metco #4 pulley and a gates 68 inch belt. Have a FTVB & Bassani catback, no other mods except a very conservative SCT tune. Will get a dyno tune this Saturday to ensure air/fuel ratio/ timing is OK. Spark plugs and gap? I must have read a hundred spark plug threads and got a wide range of opinions. Gaps from .032 to .044. The tune is very important! One range colder NGK TR6s with .038-.040 gap is what I am going with. Will get them installed prior to the dyno tune. Just looking for more street performance out of a daily driver. May take it to the track once in a blue moon. Good luck.

 

Mine are at 0.040 TR6's....

 

.038"- .040" is fine for a 4# lower. Stock is .044"- .046"

The general rule of thumb is to keep the gap wide as possible without having spark blowout.