After doing some reading on her it sounds like the 250 mercs have a decompression notch?.. Would this be on a 250efi 1999?, if so what should cranking compression be?.
dompie99
08-04-2015, 04:53 PM
I have a 225, 3.0l with decompression notches and I get 140 - 145 psi on 300X heads. .030 OS.