Bottom line....you don't want to use ANY plug wires that have crimped end contacts. The Volve distributor has a contact post in the bottom of the holes and the wires must be the Bouricord type with a hole in the end that fits down onto the post. From my own frustrating experience the crimped type will APPEAR to plug in tight into the holes and FEEL like they're seated properly but they're not. There'll be a gap between the cap post and the crimped wire end. The spark voltage can bridge the gap and the engine will run but the plug spark will be weakened. Your mileage will suffer and you may have misfires when you jump on the throttle. May also affect your emissions test results but all the while I was fighting my problem I still passed here in SoCal. This will also be worsened if you still want to set your plug gap at the high end of the spec.