1953 evinrude big twin compression # # # ?

[scot]

Is there a know number for the compression on a 25hp evinrude big twin 1953 model 25012? is it in print or a guesstimate. both of my cylinders check the same. with in 4%

 

[F_R]

OMC never did publish compression numbers. Anything you see will be from experience, guess, rumor, witchcraft, etc. Hope for experience.

 

[lindy46]

What are your numbers?

 

[oldboat1]

My '57s were in the low to mid 120s.

 

[scot]

compression came in at around an even 90.

 

[jimmbo]

Those engines had about a 5:1 compression ratio, so 90 is good.