I wanted to know if anyone had any thoughts on running a slightly hotter plug in the Jalpa. I called Bosch customer service and they recommended running a W6 Bosch as opposed to a W5 (W5 is an exact cross over to the original W235 P21 plug). The rep thought the slightly hotter plug would be advantageous and not enough of a heat range jump to cause any harm.

He also recommended staying away from the Platinum’s as this is an older carbureted car (WR5DS or WR6DS). I agree with that philosophy as I run Bosch Silvers in my old Maserati. Silvers have a much larger tip and better conductivity characteristics than the Platinum’s which were designed for emissions/fuel economy. The rep did say that they offered a W_DP0 Platinums (the "0" stands for a larger oversize tip), but felt in general the Silvers would work better in a carburetated car such as this.

At any rate, I do know the old adage try it and see, but it is winter here and I thought I would find out what others are using and/or recommend.

Thanks, John