55 horsepower - early vs later models

[Schollz]

I have seen that the newer 55's were rated for higher horsepower than the earlier models, what serial number was the HP increased? and what did they do to increase it?
What do i need to convert an earlier engine to produce the same as a later engine?

thanks!
 

[brentp4455]

i have never seen a change in power ratings. all models used the same size engines, same parts, same rpms. if you want a little extra power open up the rpms a little bit and turn up the fuel. use hotter ignition if you have a spark plug motor.
 

[Ray Mitchler]

The horse power was increased in the1955 model year,when they changed to the 555 series serial numbers started at 20001,horse power went from 55 to 72.
 

[Bruce Colbourne]

The 555 and 55 model use the same engine and the same rear-end.The only change between the two models was the paint scheme and some chrome. work.There was no nebraska test done on the 555 model.The 55-gas was tested in April of 1951.Test number 455.It tested at 60 drawbar horse power and 68 belt horse power.The diesel model was tested in October of 1950.Test number 452.It tested at 54 drawbar horse power and 60 belt horse power.The engine specs are exactly the same for both models.The tranmission speeds on both models useing 15x34 tires are exactly the same.I hope this is of help to you.