1. mopops

    mopops Well-Known Member

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    have 89 308 heads i want to get cut to up compression -rest is stock 1989 360 truck block -whats the cut number i need to do and what motor mount do i need i guess left front is different on 360s its going in 82 318 mirada thanks
     
  2. Duke5A

    Duke5A Well-Known Member

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    Anything past 30 and you're going to have to shave the intake mounting surface and use shorter push rods. It can be done, but money spent on them gaining a half point of compression might be better spent on different heads. The 308 castings are no better than your typical J head.

    Engine Quest offers an iron Magnum head that can take an LA manifold for not a lot of money. Closed chamber and flow gobs better than the early factory LA heads.

    You can reuse the 318 mounts on the 360. The passenger side is exactly the same and the driver's side can be shimmed with a longer bolt and washers. Either that or spring for a brand new set of Shumacher's.
     
  3. Jonnyuma

    Jonnyuma Well-Known Member

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    Wouldn't it be easier to use taller pistons? If you mill the heads you'll need to do the intake too.

    That assumes higher CR pistons are available...
     
    Last edited: Jan 9, 2019
  4. Duke5A

    Duke5A Well-Known Member

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    Depends on the goal. Using a piston with a different compression height would probably necessitate balancing the rotating assembly and that's about $200 right there. If he wasn't planning on tearing into the short block I would be looking at heads to increase compression.
     
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  5. mopops

    mopops Well-Known Member

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    head cut to 30 sounds like what i want to do reuse all the old parts i can -motor in car now tired 318 oil leaker, so 40 more cubes and no leaks looks better
     
  6. volare 77

    volare 77 Well-Known Member

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    You don`t want to run into the problem of sealing the intake. I ran into take many years ago when I was a kid. The heads I had installed were cut a unknown amount and I had trouble with sealing.
     
  7. mopops

    mopops Well-Known Member

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    been there seen that movie---mr belt sander fixed that thanks for the input
     
  8. volare 77

    volare 77 Well-Known Member

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    ok cool