383535 vs 311932

[jimmbo]

While the 18/20 hp shared the same displacement as the 25 in 69, they had different Pistons, Crankshafts, Carb, and as you know Cylinder Heads, The 25 Head has a smaller Combustion Chamber, to restore the Compression that the 25's Pistons reduced. Putting a 20hp Head on a 25 will really drop the Compression, might be fine if you want to run it on Kerosene, but there will be a real drop in power

 

[jitterbug127]

While the 18/20 hp shared the same displacement as the 25 in 69, they had different Pistons, Crankshafts, Carb, and as you know Cylinder Heads, The 25 Head has a smaller Combustion Chamber, to restore the Compression that the 25's Pistons reduced. Putting a 20hp Head on a 25 will really drop the Compression, might be fine if you want to run it on Kerosene, but there will be a real drop in power

Gotcha! Part would actually work but not work well is how I’m reading this? I’m in the process of getting my 25 head repaired. Thank for your knowledge and sharing