pats67copo

I have a 1965 Roadster 327/365 and want to change the spark plugs. What plugs does this engine call for and work best?
Thanks, Pat

67:72

Download the free PDF GM Heritage information kit from the link in my signature. That will tell you the original plug specs and from there you can convert to modern plug type.

That said, non-resistor plugs from that era are not commonly available any longer, so all will be resistor-type. It's also advised to go one heat range hotter than factory for better performance with today's gasoline formulations.

I like NGK brand after decades of AC Delco. They seem more reliable and the screw on tips don't come loose like they did on my last set of Delcos.

R66

Owen has given you some good advice. I use the R45S plug (or equivalent) as it has an extended electrode and doesn't carbon up as quickly when cruising the car around town.