High Compression Head with R (not Z)

[rveghte]

I am looking for information on a high compression head on a 1915 Model T that I bought recently. It has a R where the usual high compression heads have a Z (on top behind the water neck outlet). Does anyone know what company made this? What the compression ratio is? Any special combustion chamber?
Thanks!
Rick

 

[redmodelt]

Post photos. Without them an "R" will not be much help. All T heads have a number or letter cast there so could just be a stock head with the information given. Some people call a low head a high compression head. It's just a little higher then the later heads, not much but does help a little.
Welcome to the forum.