Spark plug gap

**SJAndrew** · 08-05-2011

Originally Posted by SlowNA06

The REAL answer is to gap the plugs at 0.060, run the car up to ~5,800 rpm and see if it's a problem. If it is, try 0.055. If that's not a problem, try 0.057, etc. People gap lower so they don't have to keep replacing the plugs if there was going to be a problem at a larger gap. Generally, larger gaps would get better gas mileage, but if the gap is too large, it will break-up at higher rpm.

Excellent info - thanks.

I started @ 0.055" with my new plugs.

I used to run Champion Cu cores gapped @ 0.060". I would get misfires or knock @ higher RPM (with this "setup"). I blamed Champion - perhaps it was the gap. The cheapo Pt Bosches (not gapped design) performed flawlessly with the same setup.

**SlowNA06** · 08-05-2011

Originally Posted by SJAndrew

I blamed Champion

Aside from the athletic wear, I don't have a single good thing to say about them. All their products are absolute trash. Their plugs are well-known to cause major issues.

Originally Posted by SJAndrew

The cheapo Pt Bosches (not gapped design) performed flawlessly with the same setup.

On the other hand, Bosch plugs are also known to cause performance issues. AC Delco, NGK and Autolite are the most-used by forum-goers.