spark plug gapping

**2fast4u** · 03-05-2011, 05:08 PM

im going to put new TR 55's in my car and i was wondering what is the best gapping for my car? i have a 99 trans am automatic with longtube headers and a cold air kit.

**Knight** · 03-05-2011, 05:10 PM

.055 is what I use.

**Knight** · 03-05-2011, 05:14 PM

Here's a good writeup on it though.

http://www.ls1.com/forums/showthread.php?p=2521760

**sjsingle1** · 03-05-2011, 05:41 PM

^^

**Cutlass** · 03-05-2011, 06:44 PM

For a mostly stock engine, gap those plugs at .050". Some people will say a little more gap, some will say a little less gap. And they are all right. I put mine at .050"
as long as your not way off the chart, you won't notice any difference in performance with different gaps. Stay in the .040 to .060 range and you'll be ok.

**SSnow** · 03-06-2011, 03:15 AM

Originally Posted by Knight

.055 is what I use.

Didn't GM, a few years ago, come out with a revised recommended gap for LS1 engines? As I recall it tightened to gap up.

**Cutlass** · 03-06-2011, 03:38 AM

The LS1 originally came with platinum plugs gapped at .060"
The replacement plug listed in the GM parts catolog is Iridium tipped and its recommended gap is .040".
The recommended gap for the NGK TR55s is .050" to ".060"