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Thread: 308 freshen up

  1. #1
    Part of the furniture REV308's Avatar
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    Default 308 freshen up

    Gday all

    I need to screw some more grunt out of my 308, i would ideally like 380-400 hp out of it, but Iím being a tight arse as Iíve blown all my cash on my big block 🤦*♂️

    Current specs are

    Stock crank
    A9L rods
    Cast flat tops, 10.1 comp
    Crane 286
    YT heads, big valve, unported
    Edelbrock torker
    YT bolt on rockers
    Modified quadrajet

    Makes about 185 rwkw now

    If I get the heads ported, go to something like a crane 304, yes I want to stay hydraulic, and use a 650 dp will I achieve it, or should I just go efi heads

    Cheers

  2. #2
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    Quote Originally Posted by REV308 View Post
    Gday all

    I need to screw some more grunt out of my 308, i would ideally like 380-400 hp out of it, but I’m being a tight arse as I’ve blown all my cash on my big block ��*♂️

    Current specs are

    Stock crank
    A9L rods
    Cast flat tops, 10.1 comp
    Crane 286
    YT heads, big valve, unported
    Edelbrock torker
    YT bolt on rockers
    Modified quadrajet

    Makes about 185 rwkw now

    If I get the heads ported, go to something like a crane 304, yes I want to stay hydraulic, and use a 650 dp will I achieve it, or should I just go efi heads

    Cheers
    just go vn heads they need not much work to get what you after

  3. #3
    Do you ever leave? paulzig's Avatar
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    Go to efi heads, piss that quadrajet off too lol

  4. #4
    RLF
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    casual poster RLF's Avatar
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    You're a solid cam away from getting what you want

  5. #5
    Do you ever leave? HQ308Ute's Avatar
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    with those unported YT heads you'll get 350hp tops.. go the VN's

  6. #6
    Part of the furniture REV308's Avatar
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    Port the heads and a small solid ?

    Trying not to have to change my pipes and all that stuff, thatís the reason I wanted to stay with the early heads, Iím just being lazy with the hydraulic so I donít have to adjust rockers

  7. #7
    Do you ever leave? paulzig's Avatar
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    Well, you could put in a Crane 280 lol...

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    Do you ever leave? EH179's Avatar
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    If you were starting from scratch, the vn heads for sure.

    Port the early heads for 210-215cfm flow on the intake and skim them for a 52cc chamber, the Crane 280 solid if the rockers are adjustable or Crow 5616 if staying hyd.

    Put a 2" open spacer on the Torker with a port match, with the 650 dp and you will be close to 400hp.

  9. #9
    254RWHP boat anchor EVL253's Avatar
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    the YT heads didnt they just put the big valves in them and nothing else?

    probably power to be had getting them worked over
    11 second E85 bottle fed boat anchor

  10. #10
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    Quote Originally Posted by EVL253 View Post
    the YT heads didnt they just put the big valves in them and nothing else?

    probably power to be had getting them worked over
    If they did its a backwards step without port work... Im sure keeping everything the same and just doing heads might pay dividends, with a suitable holley maybe some slighty milling of the heads to get compression up a touch...

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    Quote Originally Posted by EVL253 View Post
    the YT heads didnt they just put the big valves in them and nothing else?

    probably power to be had getting them worked over
    Just about, not much more than that really.
    Iíll see if I can get a picture off an old original set Iíve got in shed still. From memory they reemed the guides and used oversized stems with YT 1.94 in and 1.60 Ex. The ports got a very very light wave and the chamber got a bit of machine work. Looks like to try unshroud the valves a little. Itís been years since I looked at them but the bowl and short turn got SFA.
    But, they were well advertised back in their day.

    They will need a good work over and a skim for some power gains.

  12. #12
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    Quote Originally Posted by EH179 View Post
    If you were starting from scratch, the vn heads for sure.

    Port the early heads for 210-215cfm flow on the intake and skim them for a 52cc chamber, the Crane 280 solid if the rockers are adjustable or Crow 5616 if staying hyd.

    Put a 2" open spacer on the Torker with a port match, with the 650 dp and you will be close to 400hp.

    The rockers are not adjustable ones, I like your ideas though, any ideas on what it would cost to port the heads ? Been a while since Iíve had Holden heads done

  13. #13
    Do you ever leave? EH179's Avatar
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    Sorry mate, no idea what head porters are charging for a pocket port/bowl clean-up, blend seats into the bowl etc.. i would think 1k would be ballpark?

    Those combos' are actually proven with the hyd running high 12's and the solid in the mid 12's. Some have probably gone even quicker.

  14. #14
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    Mid 12ís would be good, just a quick cruiser

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    Quote Originally Posted by 46Crab View Post
    Just about, not much more than that really.
    I’ll see if I can get a picture off an old original set I’ve got in shed still. From memory they reemed the guides and used oversized stems with YT 1.94 in and 1.60 Ex. The ports got a very very light wave and the chamber got a bit of machine work. Looks like to try unshroud the valves a little. It’s been years since I looked at them but the bowl and short turn got SFA.
    But, they were well advertised back in their day.

    They will need a good work over and a skim for some power gains.
    Here's a photo of the chamber:


    I never noticed any port work but could have been a tiny amount. I discovered the oversize (5 thou in my case) valve stem thing recently, pain in the neck.

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