plug gap for denso iridiums? - Ford Forums - Mustang Forum, Ford Trucks, Ford Focus and Ford Cars

needturbo6 · 11-26-2004, 23:42

ive just put some denso iridiums (AU) in my EB2. they had a gap of 1.3mm standard but i put it down to 1.2mm. it doesnt misfire or anything, would this still be ok or would it affect the vehicles performance? there really isnt any difference to the std type plugs i was using before...
should i re-gap them at 1.1mm?

russellw · 11-27-2004, 00:00

1.0 - 1.1mm is the recommended gap.

needturbo6 · 11-27-2004, 00:38

yeh thats what i thought, as they are the std fitmet for the AU's, would the AU's have a much higher voltage igniton?

madmelon · 11-27-2004, 03:29

standard is 1 - 1.1...but the ignition seems to cope up to 1.5mm (no misfire)....i haven't tried any further. (EL GLi 6) This is with standard Motorcraft plugs.
Supposedly by increasing the gap, a minor increase in power/responsiveness is available, if your ignition can cope. The way those pointy electrode iridiums are made, you can increase the gap a fair bit more due to an effect a "sharp" point has in how easily current flows into the atmosphere. (sharper point means that a charged plate will discharge into the air reasonably quickly.) If this is used in a spark plug, it is far easier to make a spark across the gap. Therefore the gap can be wider. This is prolly why they came in at 1.3mm when rec. is 1- 1.1. Testing on normal plugs (by me) suggests that iridiums could be alot wider than 1.4-1.5mm and still work well...up to you to experiment...Another way to increase power/responsiveness/smoothness/fuel economy is to face the open side of the plugs towads the exhaust valve (at nine o'clock when completely screwed in.) This can be done by swapping the plugs between the holes and/or using special plug spacers. Its up to you how far you want to go.
DM

madmelon · 11-27-2004, 04:47

Apparently the plugs are meant to be indexed towards the intake valve. (?)....Well there's another hour fussing about the engine again...

needturbo6 · 11-27-2004, 05:55

yeh i indexed them as well as i could. i got a good result though, i pretty much got em to point all in between from intake to exhaust valve.

madmelon · 11-27-2004, 17:51

thats the way :)

fritzz · 11-28-2004, 23:44

never set the gap on iridum plug. the iridum tip is very weak to alow maximum elec flow.
on the cover of the plug it sould say "DO NOT AJUST THE PLUG GAP DUE TO THE IRUDIM TIP" well thats wat myne said

needturbo6 · 11-29-2004, 00:24

on these motorcraft ones they say "adjust gap to specifications", so i dunno whats the go...

madmelon · 11-29-2004, 02:46

the motorcraft ones wouldn't be iridiums with the tiny middle electrode...
On www.denso.com.au, it tells you how to set the gap on the plugs with a piece of wire WITHOUT having to touch the centre electrode...if u still dun wanna do it, just buy plugs that come with a larger gap- i'm sure they'd make them.