Spark plugs Need a quick answer plz

**Justin23454** · 12-15-2007, 09:40 AM

I bought ac delco iridium plugs and they are gapped .40 is this to small should I re gap to .55? Im in the middle of doing my header change so need a quick answer if anyone can give it

**shaunls1** · 12-18-2007, 10:51 AM

i think thats what there suposed to be at for those plugs. if you do gap them be very carefull its easy to break the tip off.

**splitfinger09** · 12-18-2007, 11:10 PM

Im sure this is prob to late, but I believe the stock gap is .60.

**Firebirdjones** · 12-19-2007, 03:42 AM

You can leave it as is. As mentioned stock gap is around .050 or .060 but most tuners tighten that up quite a bit no matter what plug they run.

A local LS1 tuner around here recommended NGK TR5's for mine gapped at .035,,,,,works fine although most people I see run the TR55's.

In any event I don't see any problem with .040

Sure has been alot of spark plug questions on here lately,,,,,,,,

**shaunls1** · 12-19-2007, 10:07 AM

well most people i know that run tr55's run them at .55 gap. thats what i run. it also depends on mods like high compresion and many other things.

**Firebirdjones** · 12-19-2007, 03:28 PM

Ya,,,,but you can tighten that up quite a bit. The wide gap doesn't do anything for HP,,,and actually just makes the ignition system work harder to jump a farther gap. And once the plugs start to wear,,,,it just gets bigger.
Once bolt ons start,,,most people close that gap. Smokey Yunick showed everyone 40 years ago that wider gaps did nothing. I have played with gaps on the engine dyno,,,,with multispark discharge systems and all,,,,and found nothing really,,,,so I never saw a reason to make the sytem work harder.

I run TR5's in mine,,,with a .035 gap as suggested by a local LS1 tuner. I need to investigate what the difference is though between the TR5's and the TR55's.