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Thread: 3.5 & 3.9 head differences

  1. 17th September 2015, 10:36 PM #1
    Mick_Marsh's Avatar
    Mick_Marsh
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    3.5 & 3.9 head differences

    What are the differences between 3.5 & 3.9 heads?
    Are they interchangeable?
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  2. 17th September 2015, 11:49 PM #2
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    BigJon
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    Pretty sure they are interchangeable. The only proviso is the non EFI heads are missing a small cutout in the intake port for the injector to fire through. Easily rectified with a die grinder.
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  3. 18th September 2015, 07:57 AM #3
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    bee utey
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    EFI heads also have slightly bigger valves than carby heads. There are compression height differences between early heads and later heads using composite gaskets instead of tin ones. Later serpentine engine heads only have 10 head bolts instead of 14. Later heads have better valve stem seals. However they all interchange.
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  4. 18th September 2015, 10:46 AM #4
    PLR
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    G`day ,

    pre 76 the valve dia is smaller and no stem seals , 3.5ltr

    post 76 both 3.5 and 3.9 the valves have differences but are all the same dia , use flat washer type stem seal to 1992.

    They all have numbers cast .

    ERC 0216 from 76 to 86/7 are caby type . ERC 0216 is also 86/7 to 92 EFI type .

    The EFI type has wasted stem inlet and small cut out inlet ( Jon )

    HRC 2210 1992/3 , 3.9ltr Valve guides different for use of later cap type stem seal .

    All above are 14 bolt heads , tin head gasket and aprox same size combustion chambers .

    HRC 2479 , 1994 larger ports , same valves/guides as 92/3 , smaller combustion chambers , 10 bolt , fitted to 3.9 , 4.0 and 4.6 .

    Higher number with HRC is later cast but same .

    10 bolt have some different size end threads .

    10 bolt can easily be fitted to a V belt engine but 14 bolt lacks bolt holes and require bracketing to fit to serpentine engines .edit = ( for bolt ons alt.ps ETC .)

    Either will physically bolt to any block type , including 4.4 Leyland .
    Last edited by PLR; 18th September 2015 at 12:21 PM. Reason: Add to second last sentence
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