Denny,

Is Chevgene referring to car 235 and/or truck 235 when he states that 54/55 had a 20 hp increase over 53? Which two 235 engines?

The two car 235 engines in 1953 supposedly had:
7.1:1 cr (108 hp) - low pressure
7.5:1 cr (115 hp) - high pressure
And, the Corvette 235 supposedly had 8.0:1 cr (150 hp)

The two car 235 engines is 1954 supposedly had (all high pressure):
7.5:1 cr (115 hp)
7.5:1 cr (125 hp)
And, the Corvette 235 supposedly had 8.0:1 cr (150 hp)

Supposedly, there was a 20hp gain between the 1953 Thriftmaster truck 216 and the 1954 Thriftmaster truck 235?

The truck low-pressure 216 engine in 1953 produced
92/85 (gross/net) hp (6.6:1 cr) - Thriftmaster, standard

The two low-pressure truck 235 engines in 1953 produced
107/102 (gross/net) hp (7.1:1 cr) - Loadmaster, H-D COE
108/103 (gross/net) hp (7.1:1 cr) - Loadmaster, H-D conventional

The three high-pressure truck 235 engines in 1954 produced
112/105 (gross/net) hp (7.5:1 cr) - Thriftmaster, standard
110/102 (gross/net) hp (7.5:1 cr) - Loadmaster, standard
112/105 (gross/net) hp (7.5:1 cr) - Loadmaster, H-D conventional

Maybe your head is clear, but my head is spinning.

Tim
1954Advance-Design.com
1954 3106 Carryall Suburban
1954 3104 5-window pickup w/Hydra-Matic
The 216 and early 235 engines are not "splash oilers" -- this is a splash oiler.