60 to 70hp Jetting question

[87vantage]

Ive just swapped my 1992 60hp carbs for 1992 70hp carbs on my 56ci 3 cylinder Johnson, I rebuilt the engine due to a bad cylinder and bored all 3 cylinders .030, the book calls for 50D jets I believe for the 70 carbs, what would you increase the jet size to to make up for the .030 oversize in bore? I plan to set the timing at 19 degrees? Needing dependability out of this setup? Thanks guys....

[phillnjack]

what carbs have you got ? are they the old style or the black plastic top carbs ?

50D mains in old style with a 32 at the top.

if black top carbs they 50D at bottom and 55D at the top.


But you can go a lot bigger on the jets for high performance in the old style carbs.

what is the number of the 70hp carbs ?

[87vantage]

These are the old style carbs , 92 model, I ran it today and the 50D and the 32 are lean at cruise speed? Should i go with 54D or 56D mains? whats the D and the C mean on the jets? I don't know the number on the carbs , But Ill look?

[powerabout]

c and d jets are flowed in opposite direction so you cant swap them
OMC's never have an issue with re jetting due to a rebore.

[racervboat]