I bought spark plugs for my 1952 216 engine from NAPA yesterday. When I opened the box, three of the plugs were R43, and three of them were R43S. I learned that the S means "extended tip", and those plugs do have a tip that sticks out a little bit more than the R43.
Does anyone one know if it's OK to put the R43S plugs in my engine? If so, does it matter that I've got a 50/50 mix?
