My newly acquired California Emission 1990 740-GL with B203F 8-Valve non-turbo engine came equipped with Bosch Super (R6 287) WR7DC Plugs that were in great shape regarding deposits and lack of fouling. They were quite worn down to a >0.040" gap. My goal is to pass a smog test and get maximum gas mileage. Based on various threads re: various spark plugs on this and other Volvo forums, I have chosen to use NGK BPR6EIX 6637 Iridium IX plugs to replace the Supers.

I plan to re-gap them to about 0.031" to 0.032"--up from the factory setting of 0.028". This gap setting is still within the Volvo Specs of 0.028 to 0.032", but since the small iridium center post fires much more easiy and erodes much more slowly than a conventional plug, I figure that the stock Volvo ignition will be able to deliver the advantage of a taller 0.032" spark with about the same drive as a 0.028" gap on a conventional plug.

Please feel free to re-calibrate my thinking if I am off in the weeds.

The Bosch Distributor Cap and Rotor cleaned up nicely, and with no evidence of carbon tracking or cracks, I believe that the $50+ needed to replace them unnecessarily is money that could be used better elsewhere so I plan to re-use those two parts.

One of the wires from the (#9236) Bosch wire set that came with the car lost its crimped-on spark-plug connector when I removed the wire from the plug. The metal guts from the spark plug boot stayed with the plug instead of the wire. This means that I must replace the entire spark plug wire set.

I am considering using either the NGK EUX010 54216 wireset ($56)or the OEM Style Bougicord set from FCP Groton - Volvo ($37). Most of the Volvo forum contributors to the subject of plug wires prefer the Bougicords to Bosch and cheap aftermarket sets. Low-loss, high performance wire sets like the NGK's weren't mentioned in the threads that I read. Unlike most other hi-performance (but fat)wires, the NGK's are 7mm diameter so they fit like the originals in the wire clips and holders. The NGK wires are supposedly very good at suppressing EMI/RFI even though they are low resistance wires. They have OEM style boots instead of generic connectors.

The Bougicord wire set is exactly the same as the original Volvo.

Has anyone actually used the NGK wires in their Volvo? I am trying to decide if the extra money for the NGK set is worth it.

The Nylon spark plug wire clips that attach to the valve cover have become brittle and broken off on my Volvo. Are these a dealer-only item? Where do I get (new) replacements?

Thanks for reading and responding to my questions.