Did a little research and found this head years history:
3835913 head was used first on 235 1st Series 54/55 trucks and again on 235 58-62 cars (together with 848 heads).
3836848 head was used first on 235 2nd series 55 trucks.
My 913 head is dated 1958, which confirms this casting history.
Interesting, I guess we will never know why chevy used both heads for the later 235 cars.
A stock 235 - 913 has 7.5:1 comp ratio
A stock 235 - 848 has 8.25:1
According to a 56 article by McGurk that by itself brings almost 10% increase in hp for higher rpms.
Thanks for all the input and the online manuals...
