Just got 4 NGK plugs from IPD

if i gap them between .7-.8mm that is the correct gapping right?

should they be .7, .8???

what is better??

That is the range: perfect would be .75mm.

i dunno why i didn't just let my mechanic do this..

so i replaced the plugs @ .75 and now the idle is funny

it not "rough" but it bobbs up and down about maybe 10-50 or so rpm's

about every second or so.

what gives??

just curious but..

if i gapped it as .7

would it be ANY different than .8??

Depends upon the condition of your ignition system. If its A1 then there would be no noticeable difference. However, if it was down on power (especially the points type ignition systems) then the bigger gap *could* cause a misfire - the voltage required to produce a spark that jumps across the plug electrodes increases as the pressure around it increases.

A large fat spark is required to ignite as much fuel/air mixture as possible, but if the gap is too large, then the spark will fail, so you'll end up with no ignition, hence the misfire.

Most modern electronic ignition systems don't suffer as much, hence .7-.8 is fine. It'd probably run at .9 as well, but may degrade under load.

Hope this makes sense :)

Uel