Correct spark plug gap for '76 2.7S?

The Bruce Anderson tune-up data for my car ('76 2.7S US 49 state) states W5DC with 0.55mm gap.

Okay, I have the Beru OEM equiv. & the box tells me the gap should be 0.7mm.
The Haynes tells me 0.7mm if ROW & 0.55mm for North America.

I look through my Brooklands reprints of 74-77 roadtests & the technical data states 0.7mm.

The car is US spec but now lives in the UK, so which gap to use? I am guessing the smaller gap is needed to pass a particular emission test & the wider gap may give better power.

With the emission requirements being pretty slack for a car of this vintage in this country which is the best gap?

Also, does anyone know why the US spec. cars make 10bhp less than the Euros?

Thanks, JG

I have a '76 non-S, 165HP.
I use Bosch W5DC with 0.7 mm gap according to Bosch Catalogue and Owners Manual. The plugs come with this setting. Therefore, I assume the same is applicable for the "S", but I will try to verify.

Jens

Yep, that's my point. The Beru application book says 0.7mm.

My user manual states 0.55mm, but it is a US manual.

I know it won't make loads of difference but changing the plugs on a 911 is a little fiddley & I would like the plug gap set correctly.

Cheers, JG

Jon,

With 'conventional' plugs like the NGK B-7ES, BP-7ES, or Bosch W5DC, you can use a 0.028" to 0.032" gap. It is not actually critical at all.

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Warren Hall
1973 911S Targa