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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    Right, here we go again...

    Following on from the finished valve seat/throat work a few posts back, we come to blending the top cut into the chamber & removing any rough/shart edges...

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    This is all thats really needed, just break the edge of the top cuts and blend them into the chamber.

    You can leave the chambers at that, or go one step further and clean up the whole chamber a little, smooth off all the edges of the chamber, and if you want a real tedious job, cut back the chamber to the gasket line (preferably a little before the line) to de-shroud the inlet as much as possible.

    Be "VERY" carefull not to go past the scribe mark or you'll have head gasket sealing problems (it wont !).

    I hav'nt gone for a polished chamber as I'm not trying to sell anything, but a clean up of the casting wont hurt.

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    The next thing you'll need is one of these...

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    For those that dont know, it's a burette for measuring the cc of the chambers in the head (and also the pistons in the block), and essential really to work out the compression ratio, or guess at it and melt a head gasket !

    You'll also need one of these...

    [​IMG]

    A perspex plate to seal off the chamber.

    Coat the seats of the valves with grease and fit a spark plug, which will also need sealing with a little grease.. wipe around the end of the plug and the edges of the valves to remove any excess thats squeezed out.

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    Smear a bead of grease around the edge of the chamber and place the perspex plate on top. Push the perspex carefully but firmly down onto the head until the grease has spread out in a uniform manner to seal the plate...

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    De-cant some parrafin into a squeezy washing up liquid bottle (or you'll make a bit of a mess trying to pour it straight into the burette from a 5 ltr can !)...

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    ...and fill up the burette to the zero mark...

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    ... fill up the chamber and read off the volume used (CC) from the scale on the burettte.

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    And one for Dom...

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    I've had a 30 degree back-cut put on the valves, and then the head skimmed to finish...

    [​IMG]

    A little extra work I've had to do on this head to suit the cam we're going to use is to grind some clearance for the nose of the cam to swing by, though this wont need to be done in all cases.

    [​IMG]

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    Last edited: Nov 25, 2007
  2. mr hillclimber Club GTI Supporter and Sponsor

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    Update time... it runs !

    The project 2ltr is up and running (very well), but I'll get back to that.

    Here's the last updates on the head work...

    For the cam I'm using I needed to change the valve springs or they'd go coil-bound (i.e, crush). they're a bigger wire diameter and have roughly one coil less than standard to cope with the extra lift.

    The standard springs wont need changing on most off the shelf cams as they dont have much more lift, anything up to around 435 thou lift is normally ok with standard springs, our 470 thou lift cam would have had a problem with standard springs !

    We couldnt source what we needed in time in the UK, one supplier said "we use standard springs with race cams" !... that'll be why they dont make much power and blow up then...

    We eventually found someone with some sense at Q.E.P who supply Cat Cams products. They brought some springs in from Cat in Belgium, compleate with funky alloy top caps and a new headache...

    [​IMG]

    With the new springs being a larger diameter, they did'nt fit the standard spring seats... A good friend in the trade sourced some larger diameter seats which fitted the springs perfectly, sorted... err, no.

    For those that ar'nt already one step ahead, the new larger diameter seats dont fit the standard cut-outs in the head (and some people think engine tuning is easy). So a trip to my clever machinist had the cut-outs opened up to suit the diameter of the seats.. he also had to turn down the outer diameter of the guide shoulder to suit the inner diameter of the new seats.

    [​IMG]

    With everything assembled I found a new problem (I love a challenge !). The larger diameter springs are normally used with larger diameter buckets in (proper) competition engines, so fouled the inside of the standard cam buckets!. Another good friend to the rescue, he turned off the edge of the caps to a taper and turned out the little ridge inside the bucket, "NOW" it all fitted perfectly !

    A brief moral here "NEVER presume what you buy off the shelf for an engine will fit correctly WITHOUT CHECKING YOURSELF" !. If we had assembled everything without checking, the follower would have pushed down on the caps instead of the valve, the collets would have fallen out, and you can imagine the rest...

    The standard exhaust manifold is fairly small in the port area, if it's going to be used instead of a tubular manifold then it need opening up.

    The port on the left in the pic gives an idea of the size with the gasket fitted...

    [​IMG]

    This pic gives an idea of how much metal needs grinding out, compair the standard half on the left to modified half on the right...

    [​IMG]

    If you squint, you can see the scribe line I worked to so I could achive something like this...

    [​IMG]

    I was originally going to match the shape of the exhaust manifold with the ports in the head (see further back in the thread) but eventually opened out the manifold to suit the gasket all round. If any exhaust gasses now try to re-enter the head, they'll come up against the step at the port floor and lower side walls.

    The inlet manifold was modded in a similar way (sorry, no pics.. forgot the camera). I opened out the gasket to suit the size of the ports in the head and used that as a template for the manfold. I opened and blended both manifolds back as far I could, I can see why people charge so much for porting them.

    I forgot how much of a mess grinding cast iron can be...I had to port the exhaust manifold on the back step of the house for a couple of reasons... there was a part assembled head on the bench in the shed, so grinding in there was'nt an option, and I've never found water in the back of an electrical tool to be much help, so working out on the garden wall in the rain was a non starter too!

    A txt from my wife later in the day whilst I was at work asking "why is there thick black dust all over the tv"... " no idea, cant be me, the doorstep is 25ft and 3 corners away"!... talk of a new handbag for christmas quickly had the conversation diverted!

    Well, the engine is up and running, and early signs are positive. My friends first comments after a ten mile run were "torquey as f%*K low down, comes on cam strong from 3k and pulls hard, nice rumpa idle at 1,100 rpm"!

    A quick tweek of the idle mixture (from 0.8 to 1,7) has smoothed out the idle a little, but the cam is currently on the standard marks, so a fiddle with the vernier and ignition timing (no pinking at all on standard timing and 11.25:1 with 97 octane.. but dont try this at home). Hopefully I'll get to try the fruits of my labour first hand at the weekend.

    As for the project, would I do it again or recommend it to anyone else to have a go... well, yes on both accounts. There's a lot of satisfaction in doing it yourself, though it may not be for everyone as there are a few hurdles to overcome, but it's certainly possible, and hopefully the guide above will give an idea of where it'll take you.

    As for me, I've already spoken to Superflow about a new toy for 2008...

    The project is'nt "quite" finished yet, as it'll be hitting the rollers sometime early next year (maybe with a tubular exhaust manifold), and we're fitting a lambda boss to the exhaust so I can play with the fueling on a 16v W.U.R.

    I'll keep the updates coming as and when.
     
    Last edited: Dec 20, 2007
  3. Mike_H Forum Addict

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    More good work there, and some top tips. I'm curious about why you used paraffin to measure the volumes. I was thinking that a slightly heavier oil might be better, as it would be less likely to leak out.

    Any thoughts?

    Also, are there no race springs you could have got that would be the same diameter as the stock ones - it seemed to cause you a lot of work for that minor difference...
     
  4. IanCarvell Forum Member

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    Thicker fluids like oil can trap air bubbles, I usually use a mix of oil and parrafin
     
  5. jamesa Forum Junkie

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    Thanks Jason, excellent work .. helps to explain why your own engine is so powerful and why good work is so expensive.
     
  6. mr hillclimber Club GTI Supporter and Sponsor

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    Cheers Mike..

    Easy answer to paraffin, it's cheap to waste and it does the job..:lol: .. though I still use a hand suction pump so I dont make much mess when I remove the cc plate. There shouldnt be any leakage if everything is sealed up correctly.

    A lot of work's an under statement.. we tried the obvious suppliers, one said they could then 3 days later they could'nt, another said standard springs are ok even on race cams ([:v:]), then we hit upon QEP who had a listing to suit the valve lift.

    It was'nt until they turned up we discovered the bigger diameter, and as I'd lost a week already and the bottom end was already in the car we did'nt want to wait around any longer. The service from QEP was very good and the quality of the springs and caps are exellent.. overkill for a road engine really but they're doing the job.. I'll try and catch up with Cat at the autosport show (I did'nt order them myself) and see what they can supply in the future.
     
  7. mr hillclimber Club GTI Supporter and Sponsor

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    Thanks...

    The trick with any of it is check, check and check again.. "NEVER" take anything on face value where engines (or anything else really) are concerned. It also shows even the performance industry has some odd ideas.. I checked some of the lift of some "race" cams and it's no wonder they dont produce the power they should, I know lift is'nt everything but road lift in a race application is'nt going to do the job, it just takes a bit of thought and effort to get the combination right.. of the shelf stuff is "safe", that combined with presumption makes for average results.

    Good work is certainly another thing. A good machinist it worth every penny, a "bloody exellent" one like I use is a life saver... if you find one, hang onto him.

    I've just stripped a slick-50 engine from a hillclimb car. The bottom end is totally stock (not even a lightened flywheel) with a lot of compression (heavily skimmed block & pistons), big inlet & exhaust valves but with standard size inlet ports ([:s] ) and a Schrick 304 but still using standard buckets (I'm sure I've seen that 304's should be used with bigger buckets..) and an exhaust manifold with standard ports that are smaller than the ports in the head..[:^(] .. and people make a living doing work like that..
     
  8. Tristan

    Tristan Paid Member Paid Member

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    Beautiful work , a fantastic thread . Any thoughts on using a nicer shape valve , like the TSR Stainless ones?
     
  9. mr hillclimber Club GTI Supporter and Sponsor

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    Thanks very much, glad you like it.

    I'm sure a better valve shape would help, a 0.5mm bigger valve will fit on a standard seat for a little more area/flow as well, but as for how much power per pound would be gained is only going to found with some dyno time.

    I think re-shaped standard valves do a good job in most road applications, it's all down to what people will pay. There is some experimentation in the pipeline though.;)

    A quick lift in the MK2 the engines in last night shows a slightly lumpy idle which goes the instant the throttle is touched when pulling away. Theres no flat spot at all, it just pulls away with the minimum of throttle, there's good grunt up to 3k, then a strong surge to 5. It still needs the cam/ignition/fueling setting up, and I dont like the Magnex exhaust, it has a baffle plate where it splits to the two DTM outlets, so that going soon.

    My friend said it felt like he'd just lost 10-15 hp with me on board, which on a power to weight bases is about right! :lol:
     
  10. Tristan

    Tristan Paid Member Paid Member

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    Only wondering , 'cos I finally got a DX solid lifter head to go with my balls out bottom end , and was showing my tame engine builder the VW Valves , he nearly got sick....lol

    I'm more used to old skool Fiat LAncia twin cams , which had lovely big valves , with waisted stems etc as standard .
     
  11. Jon Olds Forum Junkie

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    Excellent thread. Group A Peugeot valves inlet can be made to fit.
    I always clamp the perspex down, as a grease seal can sit 5-10 thou proud.
    Have never achieved the level of finish shown in the photos myself, 10/10 for your perservance.
    Jizer works as a comb chamber fill liquid well. If you spill it you clean as you go....
     
  12. Tristan

    Tristan Paid Member Paid Member

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    Any more info on that , Jon ? Which Pug , or what needs to be done to them? I seem to remember in the mists of time , some Antipodean chap mentioning he used Nissan valves , too...............
     
  13. mr hillclimber Club GTI Supporter and Sponsor

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    If you want some decent valves, go to R.E.C (race engine components).
     
  14. mr hillclimber Club GTI Supporter and Sponsor

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    Thanks Jon.

    I'd imagine the price of Pug valves (41mm ?) would'nt be much cheaper than some R.E.C's... 15-20 quid a piece ? Are the caps & collets the same ?

    To get the fine finish I used an air die grinder to get the speed low. A single, high speed grinder is just too wild for tape mounted in a split rod.
     
  15. Tristan

    Tristan Paid Member Paid Member

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    The 'bike people?
     
  16. 16v185 Forum Member

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    Mr Hillclimber deserving of some kind of sainthood for this one! Having seached for many years for sensible/belivable info on headwork, that works it is refreshing to read this thread....i have recently stumble upon this site www.guy-croft.com which has to be the definative engine site. Very best regs Chris[URL="www.guy-croft.com"
     
  17. Jon Olds Forum Junkie

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    more..

    Buy Guy Crofts book on twin cams, its an excellent read. The Group A Pug ones are 2mm longer than the golf 1588 flat head ones so the seats need fitting proud, along with bigger piston cutouts. Next time I have the head in bits I'll look for parts nos.
    Thinking about it, this may not be much help, as the 1588 flathead valves are prob a longer valve anyway.
    As valves have so few dimensions, then it shouldnt matter which make they originally come from. I would avoid anything cheap, like the plague. I've only had one valve failure in 25 years and that was enough. It was like a bomb going off in the comb chamber.
    This thread has inspired me to get whittling again...
     
  18. mr hillclimber Club GTI Supporter and Sponsor

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    Nope, here...

    Race Engine Components Ltd
    37 Beeches Road
    West Bromwich
    B70 6HH

    Tel: 0121 553 1103

    Or here...

    http://www.gsvalves.co.uk/

    Ah yeah.. see what you mean.
     
    Last edited: Dec 22, 2007
  19. mr hillclimber Club GTI Supporter and Sponsor

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    [:$] ..:lol: .. no not me, but those that have helped with the project when I did'nt have the right tool to get the job done the way I wanted, and a very clever machinist, have made the project much more possible... the next one(s) should be a doddle.

    I had the same problem, theres info around saying "roughly" what you should do, but not much on how to achieve it.. I thought it may come in handy for those who wanted to have a go, but were stuck on some of the finer points. I doubt there will be many pro head modders running for cover, but those spit "n" polish merchants out there will have to watch their back now you know what to look out for.;)
     
  20. mr hillclimber Club GTI Supporter and Sponsor

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    I see what yr saying Jon, but I'd imagine by the time the seat work is factored into the cost, new valves of the correct size wont be much more, if any, expensive... unless you have a source of some cheap Pug valves of course.

    I'm sure yr right about that, the valve lengths are different, though if they're a lot longer they could be used in a chambered head with the tops turned off and new collet grooves cut... but we're into the cost factor again.

    I've got R.E.C Ford crossflow race valves turned down in my race head.. they were free, and the stem the correct size (9/32) for the guides.

    They can even be straightened and re-used if you have an... accident.
     

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