2.0 Duratec - Spark plug confusion

[griggsy2]

What plugs are suitable and what should the gap be?

Currently I have some basic NGK ones that seem to run fine with a .6mm gap, however, according to the engine builder I should be running the Denso Iridiums IT24s with a 1mm gap. I've seen elsewhere on here saying up to 1.3mm....

Either way, changed them over tonight inline with the builders recommendation and after a failed start they blew the leads off, I then changed them back and all is well.

The threaded area on the Denso IT24 looked a fair amount longer than that of the NGK so wondering if I have the right ones... Any ideas? If they need a washer they weren't supplied...

Cheers,
Lee

[DCL]

The factory normally fit TR6AP13 (1.3 mm gap) on COP engines, but most tuned engines are fitted with NGK7EFS or similar and set to around 1 mm gap. The plugs MUST have a tapper seat and torqued to 10 NM (quite a low torque).

The main difference you will notice is starting - the factory plug being the best, but this can run hot on highly tuned engines.

[griggsy2]

That helps, thanks DCL.

Sounds like the NGK BR7EFS plugs are the right ones then but were fitted without being specifically gapped. Car seems to run well though so what should I expect to be the effect of 0.6mm instead of 1mm?

[F355GTS]

I'm running BR7EFS, IIRC gap is set to 31thou (.67mm) as recommended by Steve Greenald

[DCL]

If the car runs Ok, then I wouldn't worry too much. The the size of the gap is set for optimum coil performance and starting but is not critical.

[griggsy2]

Very good, thanks all.