Re: How important is the gap in sparkplugs?

Not sure about the Mondeo gap, but most spark plugs come gapped correctly for the most common setting. Assuming they haven't been bashed in transit, of course.

NGK plugs for the Zetec engine are PTR5A-13. They're preset to 1.3mm and I'd guess other makes would be the same.

Too big a gap and a larger current is required to create the spark which will result in premature failure of plug leads, dizzy contacts, rotor arms and ignition coils.

BUT it needs to be one hell of an oversize. A few thou isn't going to be an issue. Most plugs come pre-gapped at 30-32 thou which is what most cars require.

No. Hot/Cold is how far up the casing the ceramic goes before being in contact with the outer.

In which case, the gap is too small ;-)

Ford recommended closing the gap to 1mm, because the 1.3mm was too large, causing arcing between the cam cover and the lead on plug 1. This caused the very common "Misfire at high revs/load" problem.

HTH

Pete.

On the Zetec Engines, running the publicised spark plug gap of 1.3mm can cause premature HT lead failure as the wide gap puts them under severe strain. The TSB recommends 1.0mm .

Tim..

NGK plugs were what I fitted, so I'll be ok then. :-)

Thanks,

Stu.

Any idea what the gap likely to be on a two stroke? I've got to fettle my wife's moped tomorrow

-- Malc

Spark plugs are usually gapped at approx 30 thou. when bought. This is about right for many cars although not exactly right for most. For the ordinary motorist this should make little or no noticeable difference to anything. If your car is starting first time every time and running well,I shouldn't be too concerned, but as the gap widens through wear the performance will drop off slightly,but as this is gradual,you won't notice anything until you change the plugs in another 10 000 miles when your car will feel spritelier. It's more important to get the correct grade of plug for your car. Have you considered replacing the plug leads,rotor arm and distributor cap? If these are oldish,they can have an adverse effect on efficiency.

Regards Raymond

Was this in general or applicable to the mondeo?

Tim..

As a rough estimate, I was told "thumbnail size" and it seems to work well - with older engines anyway.

Si

Cheers. I just put a new one in and whilst I was at the bike shop I asked about the gap. 0.6mm the man said after looking in his book. Rubbish is my conclusion. Got to be at least 0,8mm before the bloody thing ran reliably. I've just spent all day cleaning and fettling that scooter [1] and now I need several pints.

-- Malc