I know spark plug gaps is hardly a new topic... but...

I think the new plugs were pre-gapped at 0.050" but I carefully changed them to the spec recommended by the autolite chart (and z28 manual) to 0.060". I changed 7 of the original plugs for the Autolite iridiums (I've not changed the difficult one at the back yet).

It drives pretty much the same, but the idle seems rougher than before. I've not yet changed the 8th plug in case I really would be better to set them all back to 0.50" (I don't want the hassle of doing that plug twice!) -or... is it idling rough as I still have an odd plug in there??

Would a bigger gap cause a rougher idle? -I'm not sure what to do as GM recommends less for iridiums and the manual/autolite still says 0.060??

Advice/experience with the xp5245's in LS1 appreciated!

thanks!

 

Those plug gaps are way too big. I would gap them at .035".

Rich

 

Stock gap is 0.050" not 0.060". What Rich said will work, too.

 

same here .035

 

ok thanks -It said 0.050 for 98 and 0.060 for 99+ (1.52mm (0.060) is in my manual) -but it seems really lumpy so I'm going to reduce to at least 0.050 -isn't 0.035 too small for iridiums? will that reduce power/cause me any other problems? I don't know too much about the effect of bigger and smaller gaps. My car is pretty much stock. I don't understand why the plug manufacturer lists 0.060 if it makes it lumpy?! I'm guessing the autolite iridiums aren't too much different from the ACdelcos which say they should be gapped around 0.040 I think? I don't think autolite can actually be testing these things in the car models they list, just taking the manufacturers figures I guess.