Small block heads, mk2, all the same? Now with go faster bits

Discussion in '8-valve' started by Tristan, Jan 23, 2020.

  1. Tristan Forum Junkie

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    I've been helping a mate get a few more ponies from his 1990 CE2 1.3 mk2.
    I fitted CBR carbs as a surprise for him, now he's found a fast Road cam and a 4 branch.

    I'm going to port, polish and 3 angle seat a head for it, as I have a spare.
    Are they all the same? The one I have hasn't any combustion chamber, the valves are at deck level.
    I really don't want to spend hours at this in case his one is different .
     
  2. rubjonny

    rubjonny Administrator Admin

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    there are a few variations of head, for a start hydro and solid tappet heads are obviously different but I expect you knew that already ;)
    for the hydro heads late 80s to late 90s there are a lot of engines using the same type, first thing to look out for if you have the right type is if the fuel pump hole is there if you need it, if not you'll have to convert to electric pump or you may find the casting is there just needs drilled/tapped.
    first question, what engine did your donor head come from?
     
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  3. Tristan Forum Junkie

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    It's Hydro alright John. Has the fuel pump hole, but I fitted a 12v pump when I put on the bike carbs.
    I didn't see the car the spare head came from, only told it was a 1990 mk2 as well.
     
  4. rubjonny

    rubjonny Administrator Admin

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    alright if its a 1990 then you'll be fine, the 1.0 and 1.3 bare head is the same just different cam inside :)
     
  5. Tristan Forum Junkie

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    Cool. My fear was some heads might have a combustion chamber.
     
  6. Toyotec

    Toyotec CGTI Committee - Happy helper at large Admin

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    Picture of what you are talking about Tris?
     
  7. pigbladder Forum Addict

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    thumbnail_IMG_20181006_081706.jpg
     
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  8. Tristan Forum Junkie

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  9. Toyotec

    Toyotec CGTI Committee - Happy helper at large Admin

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    I could look at part numbers and patterns and have experience tweaking such an engine. But I never had to open one of them so do not know the answer.
     
  10. pigbladder Forum Addict

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    there was a chap on the polo forums who got into these heads , he came up with the idea that the ports were already too big and ended up filling certain areas to improve it

    some pics still on google heres the before and after

    inlet_ports1.jpg inlet_ports2.jpg
     
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  11. Toyotec

    Toyotec CGTI Committee - Happy helper at large Admin

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    Lower example of the port shape, looks to have straightened the port, which will be more beneficial than shear size.
     
  12. Tristan Forum Junkie

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    This is a budget build, 3 angle seats and blend, smoothen the casting slags and that's probably it.
     
  13. Tristan Forum Junkie

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    So, this became something to cross off my list while the country is in lockdown. I threw away the inlet mani that came with the carbs, as it was rubbish, and knocked up one out of 1.5in stainless and a bit of steel plate. Previously the vacuum for the dizzy and servo was a metric sh1t load of rubber hoses and joiners, some which leaked on occasion, some which kinked, some which fell off.

    [​IMG]

    I found a nice ally fluid manifold, and made that a vacuum collection point from all runners. One end out to the servo, one to the dizzy, and one spare port if needed in the future.

    [​IMG]

    The vac mani is both mounted and supplied with vac on the 4 steel (motorhome gas line, and fittings!) pipes that were brazed into the inlet runners.


    [​IMG]
    If you look closely you'll see it's neatly tucked under the inlet runners.
    He found a s/h 4 branch, it's from a mk1 but the angle grinder and welder will make it fit. Oh and it's going to connect to a GTI exhaust system, as the 1.3 one is tiny.


    I back cut the valves, and the valve seats, and did a quick porting job, the original casting is absolutely TERRIBLE in the ports. Shockingly bad.
    [​IMG]

    [​IMG]

    [​IMG]

    I'm not finished in those pics, before anyone rolls their eyes!

    I like this picture, looking into the trumpet... You can see almost straight to the valve!
    [​IMG]


    The cam he got is a CatCams item, only about 1.0mm extra lift but a noticeable amount of extra duration.
    It'll be interesting to see how much of an improvement from the original 55bhp it is.

    It's just a bit of fun, he's on a super tight budget and for various reasons can't (and won't) fit a bigger engine.
     
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