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  1. #1
    Newbie the_german's Avatar
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    Default VN heads on 253 block

    Dear Aussie V8 friends,

    I have a Torana here in Germany for historic racing.

    There is a Holden 253 engine to assemble with VN heads and i wonder if there are problems with a racing cam might coming up ?

    Perhaps valves hit the bore or the flat top pistons ?

    Here are the Crow Cam specs of the VN camshaft i have in the Link.

    Any info is welcome.

    https://ibb.co/n1TYYDs

    Perhaps, i need a less agressive camshaft.
    Last edited by the_german; 21-07-2021 at 04:54 PM.

  2. #2
    been here .......too long Smitty2's Avatar
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    yup.. you said it
    valves will hit the block
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  3. #3
    Part of the furniture 46Crab's Avatar
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    Don’t forget you need a VN heads style cam as you early headed cam will not work with the VN heads.

    Plus…as Smitty said those big valves in the VN heads will probably hit the top of your little 253 bore.

  4. #4
    Not the Kingswood! hq308's Avatar
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    To be 100% sure you'll need to dummy assemble the engine and do some measurements. There's a few variables that will effect the outcome, if the deck of the cylinder head has been machined that will make the valve more likely to contact the cylinder block. On the other hand if the valve seats are cut deeper it will be a little less likely. A thicker head gasket will give you a little breathing space but will lower the compression ratio.

    That's a big cam for a 253 and it will need some decent compression. To bring the comp up will likely require machining the deck and running a thin head gasket. I run a similar cam in my 308 and have no issues with piston to valve clearance but your smaller bore may be an issue.

    Hopefully someone that has put VN heads on a 253 will come along and give you some better info as it can be done. One of the members here (AED) built a really strong 253 that I think is running VN heads, with any luck he'll see you post and help out. He is very knowledgeable and can be trusted to provide accurate information.

  5. #5
    Not the Kingswood! hq308's Avatar
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    Quote Originally Posted by hq308 View Post
    To be 100% sure you'll need to dummy assemble the engine and do some measurements. There's a few variables that will effect the outcome, if the deck of the cylinder head has been machined that will make the valve more likely to contact the cylinder block. On the other hand if the valve seats are cut deeper it will be a little less likely. A thicker head gasket will give you a little breathing space but will lower the compression ratio.

    That's a big cam for a 253 and it will need some decent compression. To bring the comp up will likely require machining the deck and running a thin head gasket. I run a similar cam in my 308 and have no issues with piston to valve clearance but your smaller bore may be an issue.

    Hopefully someone that has put VN heads on a 253 will come along and give you some better info as it can be done. One of the members here (AED) built a really strong 253 that I think is running VN heads, with any luck he'll see you post and help out. He is very knowledgeable and can be trusted to provide accurate information.
    AED is running early heads but it's an impressive 253 https://www.aussiev8.com.au/showthre...253?highlight=

  6. #6
    Part of the furniture 46Crab's Avatar
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    Quote Originally Posted by hq308 View Post
    AED is running early heads but it's an impressive 253 https://www.aussiev8.com.au/showthre...253?highlight=
    Rod’s off tap 253 runs early red heads.
    As you said the OP needs to dummy assemble and do some checks for clearance.

  7. #7
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    a 1.84in is the biggest valve you would want to go with that size bore

  8. #8
    been here .......too long Smitty2's Avatar
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    Quote Originally Posted by paul boz View Post
    a 1.84in is the biggest valve you would want to go with that size bore
    VN intakes are way larger...
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  9. #9
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    Quote Originally Posted by Smitty2 View Post
    VN intakes are way larger...
    yep

  10. #10
    Do you ever leave? EH179's Avatar
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    Tops of the bores will need notching to make room for the 1.94" valve. Not recommended for a high compression combo' though.

  11. #11
    Senior Member BasicQ's Avatar
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    Where does everyone think the rev range would be with those heads and cam on a 253 with enough comp to make it work?

    Peak torque rpm?

    Would the results be worth the effort on a circuit racer?

  12. #12
    Senior Member JaseQ314's Avatar
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    Quote Originally Posted by BasicQ View Post
    Where does everyone think the rev range would be with those heads and cam on a 253 with enough comp to make it work?

    Peak torque rpm?

    Would the results be worth the effort on a circuit racer?
    Depending on how heavily ported the heads and intake are (if so) I'd estimate peak torque in the high fives and peak power low to mid sevens in a 253.

    In a Torana they'll have to be carrying some RPM coming out of corners to get it moving.

  13. #13
    Senior Member BasicQ's Avatar
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    Quote Originally Posted by JaseQ314 View Post
    Depending on how heavily ported the heads and intake are (if so) I'd estimate peak torque in the high fives and peak power low to mid sevens in a 253.

    In a Torana they'll have to be carrying some RPM coming out of corners to get it moving.
    Pretty much my thoughts too. It would spend its life screaming around a circuit track.

    Some nicely worked HQ heads with std valves or the 1.8xx" that fit and a cam barely in the two twenties @.050"

  14. #14
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    Quote Originally Posted by BasicQ View Post
    Where does everyone think the rev range would be with those heads and cam on a 253 with enough comp to make it work?

    Peak torque rpm?

    Would the results be worth the effort on a circuit racer?
    depending on the casting in standard form, the mcsa would prob support 8500-8800rpm peak, and prob 360-380lbft at around 5800-6200rpm it would depend on other areas of the port and mods on how much power it would make, shrouding would be a bit of a issue on the intake valve to bore even if notched etc.
    Last edited by paul boz; 23-07-2021 at 02:41 PM.

  15. #15
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    if there was a slightly smaller casting of the same head with a 1.84 valve it would prob be a cracker at @7800rpm lol

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