SPARKPLUG GAP

[ELZE]

Quickie please

Can someone please tell me which feeller guage (metric or otherwise) I need to set the plug gap on me V6. Just ordered new plugs and people often say that the gap is already set but I have never really believed that


Cheers

[mikeWalsall]

I always check new plugs .. even with the hard cardboard tube they can get 'banged up' ..

The recommended NGK plugs are BKR5E -11 with a 1.1 mm gap ..

Before I fitted a new Dizzy cap .. rotor and leads I closed the gap to 1mm and it made a distinct improvement running LPG .. so I have left my plugs set to one mm

With alloy heads I personally think it is also wise to use some anti seize grease on the plugs threads..

[ELZE]

Good informative response thank you 1mm and copperslip it is then!

[Simon Jones]

Don't mix copper & aluminium as you may get a galvanic reaction causing corrosion . Do what Mike did and use alloy-specific anti-seize compound. Alternatively, a smear of engine oil on the threads will do just as good a job. You should not be doing the plugs too tight either.

[mikeWalsall]

A good point on tightening the sparkies ..

I wish I had taken a pic; of the threads on a couple of my pugs .. they had been tightened so much, that it had 'pulled / distorted' the threads ..

Not good workshop practise .. particularly with alloy heads ..!!

Another tip .. make sure your spark plug socket has a rubber insert .. not only to protect the ceramic but it will assist in gripping the plug when removing from the depths of the tubes .. also helping to centralise when replacing .. and save from 'cross threading' ..

[Simon Jones]

...but not so grippy that it leaves the socket stuck to the plug when you try to remove it after re-fitting. I had to enlarge the hole on the rubber insert so it would slide off a bit easier.

[ELZE]

Don't mix copper & aluminium as you may get a galvanic reaction causing corrosion . Do what Mike did and use alloy-specific anti-seize compound. Alternatively, a smear of engine oil on the threads will do just as good a job. You should not be doing the plugs too tight either.

Got that Cheers! It's all so different now, in the 60-70's we just screwed them in tightened them and forgot them?

[ELZE]

A good point on tightening the sparkies ..

I wish I had taken a pic; of the threads on a couple of my pugs .. they had been tightened so much, that it had 'pulled / distorted' the threads ..

Not good workshop practise .. particularly with alloy heads ..!!

Another tip .. make sure your spark plug socket has a rubber insert .. not only to protect the ceramic but it will assist in gripping the plug when removing from the depths of the tubes .. also helping to centralise when replacing .. and save from 'cross threading' ..

Good call!

[teenmal]

The Spark plug Gap is normally on the packet or the part No code, the plugs are designed to use this gap for the best results with a fully functional engine.

[Simon Jones]

Plugs do seem to come preset to the optimal gap for the type of plug these days. For example, I've fitted NGK LPG1's which come preset to 1.1mm. I decided just to fit them as they came out the packet and as the tips were we protected by plastic caps, there was no reason to think they would be anything other than the factory default. Also, as the tip is a very fine iridium needle, I didn't want to risk buggering it up either .

[mikeWalsall]

I fitted fitted 'normal' NGKs that I change once a year ..

According to page 196 of the Handbook .. Mazda recommend a a clearance of 1.0mm - 1.1mm so that's all right for both petrol .. for what the engine was designed for ... and LPG for which it was not ..!!