Spark Plug Protrusion into Head?

[tubman]

According to Champion, they are 13/16" reach, but they fit fine. After looking at the charts, I'll admit those numbers are confusing. I'll go with "hands-on" experience every time on this old stuff. Someone posted earlier in this thread than Offenhauser recommends "L" series plugs for their heads, which is obviously wrong. If you don't believe me, spend the $4.20 with Amazon and check for yourself. It beats "calling Eric".