The factory gap is listed in your owner's manual, which is either in your glovebox or online here:
https://www.customers.volvocars.com/owners/ownerlibrary.aspx
For my car (1998 AWD with LPT) the gap is as follows:
Spark plugs Bosch FR 7 DC or Champion RC9YC
Spark plug gap 0.028" (0.7 mm)
Turbo-charged models: Champion RC8PYP (or equivalent)
Spark plug gap 0.03" (0.75 mm)
I personally am using a larger gap based on some encouragement I read on another forum
http://volvospeed.com/vs_forum/topic/91668-slightly-increased-spark-plug-gap-for-those-running-stock-boost/
I started using NGK BKR7E which I now see is maybe a bit on the cold side for my car, and I found the idle a bit rough. Increased plug gap made things real smooth.
--
1998 V70 AWD->FWD->AWD Turbo 215k+
|