Water cooled manifolds - '72 240z | The Z Club of Great Britain
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Water cooled manifolds - '72 240z

Discussion in 'S30 (240Z,260Z,280Z) Exhaust and cooling systems' started by uk66fastback, Mar 10, 2019.

  1. uk66fastback

    uk66fastback
    Z Club Member

    For those with US cars of this year that had the later design with the water-cooled manifolds, have you kept that system when working on the cars over here - or blocked off the pipework - probably all bunged up with sludge anyway - and bypassed it?

    I have also junked the smog unit and am wondering if anyone has done this, how they resolved the six pipes that go into the exhaust manifold? Some of the bungs on the balance tube will fit into the manifold and block off where these pipes went. So I'm torn between buying some of these bungs or cutting off them off the pipes and welding up the holes and reusing them ... that is if I don't end up buying one of Sean's headers (sorely tempted) which would remove the problem ...

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    Last edited: Mar 10, 2019
  2. SacCyclone

    SacCyclone
    Z Club Member

    Pipe plugs for the exhaust manifold Mike.
    I have plugged the water lines or changed out the intake manifold to the older style w/o water passage.
    Mike
     
  3. AliK

    AliK
    Z Club Member
    Staff Member Moderator

    I have a 260 but the principle is the same.

    When I removed mine, it wasn't blocked at all.

    The benefits: carbs no longer hot - in fact they are fridge cold to the touch and often have condensation on the domes after a spirited blast! Less pipework to go wrong (mine sprang a leak) and a cleaner engine bay.

    The downsides: the manifold after carb insulators is much hotter than before. No arctic condition driving for me any more (as if my Z would see a winter!!!!) as the carbs may ice up and finally, manifold temps not constant - again, not sure that matters in the real world use of our Zs.
     
  4. toopy

    toopy
    Z Club Member

    There's no real point of all that shenanigans on a UK car, it just simply doesn't get cold enough for long enough to be effective, and who would be out in the snow and ice anyway, unless you were fortunate enough to have a rally Z! :D

    I removed mine many years ago, the manifold pipe wasn't completely gunked up, but as near as dammit, the rubber hose from the thermostat housing to the front of the manifold however was solid with crud, as was one of the bends in the metal pipe that goes round the back of the block.
     
  5. franky

    franky
    Z Club Member

    is it to cool or to circulate heat to prevent carb icing in colder climates?
     
  6. Rob Gaskin

    Rob Gaskin Treasurer in training Staff Member Moderator

  7. uk66fastback

    uk66fastback
    Z Club Member

    Thanks Rob, I did actually do a search and couldn't find anything. I did have the final reply on that thread as well, so even more embarrassing. Technically, it is water-heated, franky, you are right ...

    Thanks for the advice, everyone.
     
  8. franky

    franky
    Z Club Member

    Sometimes things don't seem to quite turn up in the search. FWIW you can get issues with carb icing in the UK, however i'm not sure if the SU's are prone to it. I wonder how the thicker oil inside when cold effects things?
     
  9. AliK

    AliK
    Z Club Member
    Staff Member Moderator

    Well, I drive mine hard and when I stop in a car park to adjust something under the bonnet, they are cold but never freezing cold.

    Damper oil viscosity change is not noticeable - to me at least. If anything the thicker the oil the more smoothly they operate when you go back on the power (goes briefly rich). Those dodgy triples of yours on the other hand .... :p
     

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