I have a RSA-10 fuel servo on my IO540 that is in a Legacy and.recently I have done 3 modifications :

1) Added an inlet scoop which provides 2" more MP at 200knots
2) Turned up the RPM from 2700 to 2850 RPM
3) Advanced ignition timing by 2 degrees

I now find I can not get EGT down below 1370 F. I think I am running too
lean. I think it makes sense to increase the main jet size. Is this
correct? If so, from what dia to what dia must it increase? If not, what is
the solution?

 

Maurits