Difference between clarke compressors

  1. normspanners Member

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    and therefore making the gasket cooler ? This head is cast and you can clearly see the piece out of the gasket you also can see the size of the inlet chamber which is the top section and the fact that if the gasket is made wider it will be in cooler air.
     
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  2. eil Member

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    1,767
    N Wales
    Its a very common problem of these head gaskets blowing between the high and low pressure sides and the thing is the manufacturers haven't done much to solve the problem it appears, I can see the merit in your idea Norm and it appears to have worked by your tests, I will give it a go next time I get the problem, but most of my pumps are Broomwade and one T30.
     
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  3. normspanners Member

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    PS the blue on the head face is somekind of glue they use to hold the gasket in place but as the head distorts in the middle IMO it lifts the pressure off the bridge there should be a bolt hole in the centre screwing down into the valve plate even A 6mm would help the length of that bridge is massive to be unsupported the peripheral bolts are spaced quite evenly in comparison, plus the fact the gasket is wider there!
     
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  4. normspanners Member

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    I repair clayton dewardry compressor pumps on diesel engined water pumps and they run and pump air (for the inlet venturi which causes a vacuum in the inlet hose) 24/7 for months at a time and we now are making copper gaskets as they break down, it takes longer to do, but the job is fix and forget.
     
  5. rtbcomp

    rtbcomp Moderator Staff Member

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    Air is drawn into the pump.
    It is compressed
    It heats up
    The heat is transferred into the head/block
    Heat is transferred into your modified gasket
    Heat is picked up by the airflow over the gasket
    The gasket cools down
    Therefore the incoming air is heated up

    You are now compressing warmed up air in a slightly cooled pump, you haven't removed any heat from the system.

    Your extended gasket may conduct heat away from the air in the head into the head/block, but the airflow from the inlet won't help with cooling.

    One thing you can do to cool the input air is to extend the inlet away from the pump & motor, on the SE16 the filter is placed in the worst place - over a hot motor.
     
  6. normspanners Member

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    8,852
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    Isnt that what I have said all along !!!!!
    If the gasket is cooler,then due to conduction, the head /valve plate area is cooler at the inter phase and less likely to distort, with the gasket being stronger the whole job is stronger and less likely to blow.
    It does not concern me unduly, that the air is slightly warmed but , in practice the fact that the air is warmer seems to make hardly any difference to the speed of pumping or efficiency (even though the air would be slightly less dense) but it has already been drawn into the chamber as coolish air, I doubt because it is now slightly less dense it will go against the inlet flow of cool air to get back out of the filter.
    Also
    The point the pistons seize is at the top between the two cyl because that is the hottest area by a along shot, due to it being furthest away from the cooling fins.
    So if that areas temp can be reduced by radiation due to the cooler and better conduction of the copper gaskets,that again prevents the pistons overheating and galling, the composite gasket tends to act as an insulator not allowing conduction to soak the heat away.
    I have corrected my self I had written convection by mistake (due to normally talking about water cooled cyl/heads cooling systems) I meant to write radiation. Sorry
     
    Last edited: Aug 15, 2014
  7. normspanners Member

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    8,852
    northwales
    PS another point here that I had not noticed is, if you look at my pictures the gasket has blown slightly to one side of the bridge and that side is the side furthest away from the drive pulley inbuilt fan which will be keeping the left side of that head (as in the photo) and also the block cooler.
     
  8. rtbcomp

    rtbcomp Moderator Staff Member

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    From post 32 "Yeah it was just my idea for the top gasket to help keep the temp down " and "copper will be in the cool inlet air and that would transmit that coolness through the gasket into the body and the head block interphase."

    I agree 100% that a copper gasket is better, but I wanted to make it clear that airflow over the gasket won't make any difference to the heat generated in the pump. The coolness transmitted to the head/block interface would be lost by the hotness produced by compressing warmed air.

     
  9. normspanners Member

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    8,852
    northwales
    Yes in the area of the block/ head interphase, to me it is fairly obvious that it would NOT keep the pumping effect temp down because that is a natural physical phenomenon from compressing gasses.

    That Sir is obvious and was NOT implied in any way.
    Thank you for quoting that and pointing out, the gasket would cool the casting/ally area, thus helping prevent distortion of the head.
     
  10. rtbcomp

    rtbcomp Moderator Staff Member

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    Never disputed that the copper gasket would even up the temperature between the block & head, it does this by conduction, extending the gasket into the incoming air stream is counterproductive in my opinion, it just introduces heat where you don't want it and any cooling will be local to the inlet side, whereas you want uniform cooling to avoid distorting the head.
     
  11. normspanners Member

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    8,852
    northwales
    No I disagree
    The most heat will be produced by compression at the top of the block and the head of the pistons ( which again heat will be transmited by the piston rings into the cyl wall) the heat then will travel into the first fitted gasket and on into the valve plate (h/p side will be considerably hotter) therefore some heat will be lost into the cooler air inlet chamber side, which the wider gasket will aid.
    then continue through the top gasket into the cyl head where it will be finally released into the ambient air, therefore reducing the temp of the effected hot area ie the uppermost middle area of the block.
     
  12. normspanners Member

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    8,852
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    You will never get a compressor head /valve plate at a uniform temperature it is physically impossible but the copper aides that transfer and if that gasket is cooler by giving a little of it's heat to the incoming air so be it, in the grand scheme of things the gasket being cooler is by far the better option, the extra heat introduced into the incoming air will be marginal at best, due to the massive surface area of the inlet chamber it will gain more temperature from that surface, than it would from 5mm of copper gasket. All the composite gaskets do is initially seal the two different air pressures areas, but being composite they also insulate the two faces and seal the heat in . That is why the centre top of the cyl's area ends up blue.
     
  13. rtbcomp

    rtbcomp Moderator Staff Member

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    I said "But the heat from the head/block will be transferred back into the top of the cylinder via the gasket"

    You said "No I disagree ........................therefore some heat will be lost into the cooler air inlet chamber side, which the wider gasket will aid."

    We're both saying the same thing here.

    That's what worries me, you don't want heat introduced into the inlet side.

    I suspect the longevity of the modified gasket is due to superior materials, and the modified shape of the gasket has a negative, although insignificant, effect.

    If it was down to me I'd insulate the internal surface of the inlet chamber to stop heat being conducted inwards.
     
  14. normspanners Member

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    OK maybe we should agree to disagree,
    My only evidence is that the ones that I have done have worked reliably, especially the one that I regularly visit at my wifes garage, its duty cycle (in my opinion) is being vastly overworked.
    It is running most of the day for 12-13 hrs. i also have changed the control and adjusted the differential to minimum (one bar), so that the pressure does not drop too far before the pump cuts in, the air guns will not operate efficiently at low pressures and they hold the trigger pulled until the comp cuts in so that it gets up to full air, that will allow hem to undo ridiculously tight wheel nuts that have not been torqued correctly by other garages
    or the hub /drive shaft nuts which can be virtually impossible on your own to undo.
     
  15. rtbcomp

    rtbcomp Moderator Staff Member

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    Sure, but I'd bet a penny to a pound that the improved reliability is due solely to replacing the composite gasket with a copper one.
     
  16. Wallace

    Wallace Member

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    Location:
    Staines, Middlesex, England.
    The original gaskets on my SE16 lasted 13 years before blowing, the outlet gasket went first then the head. I knocked up new ones from good quality high temperature gasket material but copper makes sense.

    While the head was off I had a play with some adhesive wheel weights on the pump pulley shifting them about to see if I could improve the balance. It's definitely smoother and a little quieter now, next service I might take the pulley off and check it on my bike static balancer then some knife edges.

    I also have a 6N2 Polo air filter housing to fit remotely hoping to reduce the induction roar/knock that the original filter has.
     
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  17. normspanners Member

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    8,852
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    that is one big problem with those for some reason they are LOUD the one at the garage is right by the mot ramp and annoys me when i visit, if it was mine it would be gone!!!
    the four times larger broom wade thumper I got to replace it is less than half the noise but they havnt the time to swap and 'oh its still working well so just leave it for now'
    Ps they put the first one outside at the back and it was removed by someone who wanted it more!!
     
  18. eil Member

    Messages:
    1,767
    N Wales
    Wallace, you will notice a marked reduction in noise when you put the car air filter on that's what I have done with two of mine.
     
  19. rtbcomp

    rtbcomp Moderator Staff Member

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    I've got a Metro oil filter on a length of vacuum cleaner hose on mine. I've put the filter in a filing cabinet drawer (under 'F') and the noise is much reduced.
     
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  20. Wallace

    Wallace Member

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    Location:
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    I did a trial fit and there was a definite improvement, just need to work out a way of fitting it. The only reason I'm using that filter is it was available and free from my stepsons damaged car, the filter areas are huge so I'll never need to replace them!
     
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