Modified 8v project head

Discussion in '8-valve' started by mr hillclimber, Nov 5, 2007.

  1. mr hillclimber Club GTI Supporter and Sponsor

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    Exellent find on the last Vizard article (I've had the first one for a long time). I've been trying to buy that from the states, they answered my first enquiry but did'nt bother when I asked how/where to send the payment.

    That may have answered a long standing question of mine, where did the 40/35 combo come from... good o'l Mr Vizard... though some idea's regarding inlet/exhaust flow ratio's have changed over the years.

    The race Crossflow (Ford Kent engine) R.E.C valves that Dave Walker used are still relevant, that's what mine are based on in my hotrod/hillclimb head. The Isky springs are "ok" to a point, but with the radical hotrod cam, they used to break all the time, though the owner did claim to use 9,500 regularly !

    When John Read originally changed them to the Crane springs for the previous owner, the problem went away in his hands. I have since had to replace 1 spring in the early days of the engine, which is much better than all eight every half season that they used to go through !

    I'll report back on this when I strip the engine in the next couple of months.
     
  2. 82erGTI Forum Member

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    Indeed, very interesting articles... are there any similar "how to's" around for the 16v cylinder head ?
     
  3. OldDirty Forum Member

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    a little question - what kind of grinder rpm should I use in the first part of the grinding ?? as a matter of fact what rpm should I use in the finishing part [:D] ??
     
  4. mr hillclimber Club GTI Supporter and Sponsor

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    You'll ideally need a vairiable speed die grinder. Makita do one, the last time I looked they were around 160 quid (from memory) from a tool supplier on line. If you struggle to fine it I think I saved it to favorites, so I maybe able to dig it out.

    I used a fixed speed Makita for all the rough work, which runs at 22000 rpm, and an air grinder for the finishing which you can obviously control yourself. I was lucky to be able to use the air tools at a friends but I've seen the same results achived with a vairiable speed electric grinder.

    A fixed speed grinder is fine for the rough cutting, but too fast for the fine finishing, and a normal household type drill is too slow for both.
     
  5. OldDirty Forum Member

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    thanks a lot mate , went thru the whole thread , awesome job on that 8v , i`ve got a spare 16v 9a and a 16v kr on my g2 , and now I dont realy know what to do...should I try to p&p the 9a myself and if it goes out well do the kr , or sell the 9a and give the kr to some profesional...or hang myself ;D ... a good grinder cost around 150 , carbide burrs are over a 10r each , ok i`l hang myself [:D] thanks again for your help
     
  6. dk210kgs New Member

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    So much for a simple 8v 2litre engine conversion I had in the pipeline. This articles got me hooked on going much further.

    Fantastic article :) and a great excuse for my dad to buy more tools me thinks.
     
  7. jc.. Forum Member

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    just took delivery of some of those nice tungsten burrs, tested them out on a cast turbo mani that needed cleaning up. seriously good peices of kit
     
  8. ONZ

    Onz New Member

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    great thred mate :)
     
  9. Tristan Forum Junkie

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    Back to this again..... Common engineering science has shown that a slightly rough finish is desirable for inlet ports , but is a "mirror" or smoother finish an adb=vantage or not in the combustion chamber , and in the exhaust port?
     
  10. MR D Forum Member

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    Bit weird ?

    This looks the business !
    http://www.techtonicstuning.com/showpart.asp?partnum=109.912T

    Had a nightmare this arvo trying to strip down the spare head ! Think i bought the wrong valve spring compressor,i got the one for valves the are flush with the top of the head.But i needed the one for valves that are an inch deep :dash: .
    I got round it by using a spark plug socket on the valve cap,no ideal,and there is no way i can put it back together now,without the propper tool,anyone know which one i need ?
    After a good clean up what i thought were cracks were just marks on the head :thankyou: .
    All looks to be in pretty good order really,valves were tight in the guides,don`t show any sign of wear etc.
    Popped them in my dril and gave them a clean with some emery paper

    [​IMG]

    [​IMG]

    [​IMG]


    Need to get some carbide burrs,and a Makita varible speed die grinder next,going to chop out the guide boss,so it`s flush.once i have had the guides removed,new guides will be bullet nosed for extra flow !
    I also measured the head limit it can go to is 132.60mm my head measures 135mm,so i will be fine getting 40 thou off,going to get them to broach it to make sure it`s flat,prior to the skim,but skim will be te last thing i get done,along with getting the gasket faces skimmed too,will get new s/steel studs for it too..


    One other thing i noticed while stripping down,there were no oil seals fitted to the valve stems ? do they fit ontop of the guides ?

    Another edit !
    Just measured my valves with my calipers ! it does not add up !
    According to haynes book of lies my inlet should be 40mm but it`s 41 ! the exhaust should be 33mm but it`s 35 ! The valves all have T-T stamped on them ? could this head have been played with already ? Looking at the inlets and around the bowl under the seat,looks like its been modified,not half as wrough looking as the example i saw of a dx head prior to work being carried out ! on here ?
     
    Last edited by a moderator: Jan 23, 2018
  11. Mike_H Forum Addict

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    Have you already ported that head? It looks like it's had some work done already, which you'd expect with those valve sizes. Can you take some close-up pics of the ports and combustion chambers. Don't go fecking about with it till you know what you've got.

    Comparing the ports to the gaskets would be a good move too.

    And yes, the stem seals go on top of the guides. Check for play in the guides before you start removing them. About 1mm at the valve head is the max, with the valve pushed open.

    You don't need the fancy valvetrain if it's not a full race engine. You could get the head professionally ported for that cost!
     
    Last edited: May 7, 2009
  12. MR D Forum Member

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    No i bought it for 50 ! it was advertised as a standard dx head ! but with the valve measurements it does not add up !
    i have not touched it ,but it does look slightly different to the standard one in the pics on here.Give me 5 i will try and get some close up pics :p
     
  13. MR D Forum Member

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    Here are the pics,sorry about the rubbish quality,and the fading light [:$]


    [​IMG]

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    [​IMG]

    Where the injector comes through looks different ! not sure if the rest has been played with ?
     
    Last edited by a moderator: Jan 23, 2018
  14. Mike_H Forum Addict

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    Ports and combustion chambers look pretty standard, although the pics aren't the clearest.

    Still the bigger valves are a bonus. Measure the valve seats and make sure they've had bigger seats put in to match the valves, otherwise they won't do much good. Valve seat insertion is 100+ for 4.
     
  15. MR D Forum Member

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    Will check tomorrow,weird how it`s got bigger valves.must have run out of the other ones when they built it ?
    Did put a gasket upto the exhaust port,and there was still a little bit of material there.


    That`s quite expensive,got a mate who works at an engineering place,see if he will do mates rates.they looked ok before i took them out
     
  16. mr hillclimber Club GTI Supporter and Sponsor

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    All looks standard, does seem strange at that size. Sure the verniers are correct ?

    Just apply some grinding paste to the seats and give the valves a couple of spins, that'll show you where the seats... seat.
     
  17. MR D Forum Member

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    Yeah deffo,measured them twice to check,also measured seats to check someone had not just bunged bigger valves in,seats match valves ?
    Looks like i am going to port it then..

    I maeasured the valves at their widest ,thats right or am i being really stupid [:$]
     
  18. mr hillclimber Club GTI Supporter and Sponsor

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    Yeah thats right.... very strange tho.

    Good call, follow this guide and you wont go wrong.
     
  19. chrismc Forum Junkie

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    I had exactly the same issues with a Magnex 6x4 backbox on my old 8v Jason. It was a replacement system for an earlier DTM system with them rotten solid downpipes that kept cracking[:x] If only id known then what i do now!. The 6x4 backbox system immediately strangled the car terribly at high RPMs

    Alan @ Autotechnik in Southampton eventually cut the box open & it was shockingly restrictive in design[:s]

    I ended up taking it up with Magnex directly & eventually got a full refundon the basis their "Performance" exhaust was actually a "Lack of performance" exhaust! Would never use a Magnex again..Went for a Supersprint system after that & the difference was chalk & cheese;)

    If you are planning on a project 16v head Id be very interested to see the results & very tempted to commission you to prepare one for me judging by this thread. You are a man that clearly knows his onions (& cylinder heads!):lol:

    Am I best off discussing this with you by PM??

    Good work again on this thread. A most informative guide:thumbup:
     
  20. mr hillclimber Club GTI Supporter and Sponsor

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    Hi Chris...

    Glad you like it, and thanks to all those who have, and still look at this "sticky", nice to see it's still popular!

    I'm affraid there's a lot of marketing bull$*it out there, money driven I'm affraid.

    I visited the (then brand new) Magnex factory ten years ago, a very impressive place! They did have some old school development engineers in the early days who knew how to design an exhaust. I ran a road system on my Mk1 when standard, it gave a solid 5 hp extra, and the same back box was used later on when it was close to 160hp at the wheels, so they could actually make an exhaust.

    Maybe later on the "bean counters" took over... probably why they went bust.

    Supersprint tailboxes have the same sort of layout when twin tailpipes are used as we did on the back box above.

    If you have a search through the 16v engine section there is a flow chart for a 16v ABF head I did a while back, under "16 head flow" or something like that.
     

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