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  1. #1
    Member casterbased's Avatar
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    so is 2mm the max i can take off an 8v head?

    what comp would you get with 2mm removed and a mi16 head gasket?

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    would you bend valves if you go more than 2mm
    2008 Fiesta XR4 "ST150"
    -Cosworth cams, Cosworth intake manifold, CIA "K&N", Dream science, De-Cat, Eibach, Bilsteins, White Line sway bar "rear", EBC Rotors and pads, Goodridge brake lines, OZ Racing wheels, Toyo R1R

    1964 S2a Land Rover LWB
    -Served with the 1st Australian Task Force, Vietnam, original condition

    1994 S3 205 GTI
    -3L 406 V6 Conversion

    2009 Husqvarna TE510
    -Blinged

  2. #2
    1000+ Posts PeterT's Avatar
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    Quote Originally Posted by casterbased
    so is 2mm the max i can take off an 8v head?

    what comp would you get with 2mm removed and a mi16 head gasket?

    would you bend valves if you go more than 2mm
    Mi16 and 205 gaskets are identical. You won't bend valves but you won't have any rigidity in the head face. You can use a thinner copper gasket to increase the CR. I've successfully used a 0.5mm gasket. Std. is 1.32mm.

    '92 205 Mi16
    '90 Mi16x4

  3. #3
    1000+ Posts alan moore's Avatar
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    From what I remember you could lop 2mm off a series 1 or 2 head but probably not a series 3. I did all this 15 years ago. Even with 2mm off C/r will only be around 9.5 - 9.7. Peter T would be able to tell you more. The valves will not hit the pistons on the early heads with a standard cam. The series 3 heads are much better and I believe these are the same as late alloy block 405 heads.

    Pick up one from a wrecker and modify it, and only have your car off the road for a day to put the new head on.

    Valve timing will be retarded somewhat with a 2mm cut off the head which will tend to make the motor better up top and lose a little down low in the revs.

    The best thing that can be done to the early heads is sort out the exhaust port as it has an EGR port associated with it that is not used. I filled mine with a threaded aluminium rod and then ported it. From what I remember the stock 405 cam is bigger, at least on the iron blocked versions and probably on the alloy, but I have not fitted one to an earlier head as I had a custom cam made.
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  4. #4
    Member casterbased's Avatar
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    Quote Originally Posted by alan moore
    From what I remember you could lop 2mm off a series 1 or 2 head but probably not a series 3. I did all this 15 years ago. Even with 2mm off C/r will only be around 9.5 - 9.7. Peter T would be able to tell you more. The valves will not hit the pistons on the early heads with a standard cam. The series 3 heads are much better and I believe these are the same as late alloy block 405 heads.

    Pick up one from a wrecker and modify it, and only have your car off the road for a day to put the new head on.

    Valve timing will be retarded somewhat with a 2mm cut off the head which will tend to make the motor better up top and lose a little down low in the revs.

    The best thing that can be done to the early heads is sort out the exhaust port as it has an EGR port associated with it that is not used. I filled mine with a threaded aluminium rod and then ported it. From what I remember the stock 405 cam is bigger, at least on the iron blocked versions and probably on the alloy, but I have not fitted one to an earlier head as I had a custom cam made.

    STOCK 405 CAM IS BIGGER? WHAT DO YOU MEAN BY BIGGER?

    i'm getting a cheap spare 405 8v motor from a upull it wrecker.

    my gti's are both s1, the 405 engine has the differenrt head, with the longer, more tubular intake manifold. do these 405 heads flow better?
    2008 Fiesta XR4 "ST150"
    -Cosworth cams, Cosworth intake manifold, CIA "K&N", Dream science, De-Cat, Eibach, Bilsteins, White Line sway bar "rear", EBC Rotors and pads, Goodridge brake lines, OZ Racing wheels, Toyo R1R

    1964 S2a Land Rover LWB
    -Served with the 1st Australian Task Force, Vietnam, original condition

    1994 S3 205 GTI
    -3L 406 V6 Conversion

    2009 Husqvarna TE510
    -Blinged

  5. #5
    1000+ Posts Dave's Avatar
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    The 405 cam has longer duration than the early 205 cam. I have been through all of this on my bx. I have a DFZ block and a DKZ head now. I had the head reconditioned with 3 angle seats and ported. I have the original cam and the cam from the later car sitting down in the shed and the later cars definately have a nicer cam. I'm running a [email protected] cam that Alan Moore used in the 205 he mentioned. Careful getting too much compression though as it makes these engines ping quite easily at lower revs. I have managed to tune mine now, just using the carburettor and std distributer so it drives nice and doesn't ping, initially i thought programmable efi would be the only solution, but a lot of testing has finally paid off and its running nicely.
    These engines really come alive with a bit of compression and the better flow of the late model head.

    Good luck mate, make sure you get an adjustable pulley for the cambelt, also the bolt hole on the right hand engine mount on the head needs a bit of massaging with all this playing around.
    Since you have efi though you may need to buy a haltech/motec ecu to get it running right as you wont be able to change the fuel or timing like I did.


    Cheers,

    Dave


  6. #6
    Member casterbased's Avatar
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    why didnt you richen it with the afm spring

    i can get a cheap set of new webbers , but i think efi is better
    2008 Fiesta XR4 "ST150"
    -Cosworth cams, Cosworth intake manifold, CIA "K&N", Dream science, De-Cat, Eibach, Bilsteins, White Line sway bar "rear", EBC Rotors and pads, Goodridge brake lines, OZ Racing wheels, Toyo R1R

    1964 S2a Land Rover LWB
    -Served with the 1st Australian Task Force, Vietnam, original condition

    1994 S3 205 GTI
    -3L 406 V6 Conversion

    2009 Husqvarna TE510
    -Blinged

  7. #7
    1000+ Posts Dave's Avatar
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    What afm spring? - The Bx GT comes standard with a Weber.

    Of course EFI is better, i'm just saying you will have to retune it.

    Dave


  8. #8
    Member casterbased's Avatar
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    Quote Originally Posted by Dave
    What afm spring? - The Bx GT comes standard with a Weber.

    Of course EFI is better, i'm just saying you will have to retune it.

    Dave
    learn something new every day

    are you going to stay with the weber?
    2008 Fiesta XR4 "ST150"
    -Cosworth cams, Cosworth intake manifold, CIA "K&N", Dream science, De-Cat, Eibach, Bilsteins, White Line sway bar "rear", EBC Rotors and pads, Goodridge brake lines, OZ Racing wheels, Toyo R1R

    1964 S2a Land Rover LWB
    -Served with the 1st Australian Task Force, Vietnam, original condition

    1994 S3 205 GTI
    -3L 406 V6 Conversion

    2009 Husqvarna TE510
    -Blinged

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