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Thread: 425-455 olds

  1. #1
    1975sleekcraft
    when i bought my boat the guy was running a 425.i blew that motor up quick.
    i bought a junk yard 455,rebuilt it,now i have had three succesfull seasons.
    i know a 455 crank wont fit in 425.
    my 425 came with C heads-do 425-455 heads interchange??????

  2. #2
    Taylorman
    yes
    both share the same block, just different rotating assembly.

  3. #3
    malcolm
    The only thing different would be the lifter bank angle on the 425. The C heads are 455s already. 425 heads would be As and Bs.

  4. #4
    1975sleekcraft
    so what your saying is the guy before me put the 425 in with 455 C heads on it??

  5. #5
    Taylorman
    C heads fit 425's and 455's.

  6. #6
    malcolm
    Yeah, they're all about the same. My 455 has A heads on it. So what happened to the 425? They have forged cranks and a shorter stroke, should've been a little harder to hurt. I think the 425 has a different flywheel bolt pattern also. Just things I remember reading on Realoldspower.com.

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