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Cylinder head gasket


Martin White

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Thanks again guys. Will be doing a thorough clean and a full flush through once engine up and running g again to get rid of any internal crap that I cannot get to. Was recommended half a dish washer capsule to dissolve out all the out that has made its way into the waterways. New one to me

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Just cleaning up the head and tested valve seating with penetrating fluid all seems ok. However, one of the valves is not completely flat and has a slight bump as though the valve stem is "pushing" through slightly. I have another head so I suppose I could swap that one valve over. Or while I have the head off replace all valves and guides (and seals although I have seen hundreds of conflicting advice around these)?

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if you fit seals there's a  very good chance you will seize a valve stem due to lack of lube .the engines are not designed to use stem seals 

if you replace the valves ( why) you need to recut the seats then you remove some of the lead memory you really need to keep 

the raised head is just an alternative method /manufacturer its  not a problem

pete

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Tightening torque is dependant on what lubricant is used, so check the workshop manual carefully (I used ARP big end bolts, they use a special lubricant and specify a torque lower than when using engine oil, all on their excellent spec sheet) I guess using oil means you will have, if anything, a higher clamping force. Not enough to f=damage anything, so shouldn't harm anything.

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I don't use anything in the block, just screw the studs in firmly but as Pete would say not Gorilla tight, a bit of assembly lube around the shafts when lowering the head in place - just a smear, keep it off the gasket) and then tighten down as per the book. The important thing is to retorque after a bit of mileage, once things have settled / expanded / vibrated fully into place.

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  • 2 weeks later...

So guys you can see from my last post it has been a couple of weeks.

Head should have been back on by now. 6 hours removing a stubborn stud 1 weekend gone

Nuts kept shearing whilst torquing up another weekend gone 

so ordered correct cylinder head nuts from Canley classics And I am still having the same issue. I torque up to 20lb/ft then 35 but when I torque up to 46 ‘crack’ nuts shear and back to square one. Does anyone have any idea where I am going wrong here? Studs were also from CC. Getting a tad frustrated! 


 

 

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Have you checked your torque wrench?

I ruined a rebuilt engine by torquing the head studs in - I know! no need, they should be hand tight, but a manaula said 60lbs-ft.    I did that - and split the block!  One of the front studs is near the edge of the face, and it cracked.    One scrap block, bugger.

But then I checked my torque wrench!   And it was delivering 100lbs-ft, when it should be 60.  A check is simple to do.    Grip the drive bar in your vice, with the handle horizontal.  Hang know weights from the handle, ahving set it to an approriate setting, and move the weight outwrads until the wrench clicks.  Then known weight, divined by the distance from drive bar to the strop hanging the weight is the torque at which it has clicked.       Easy, but fiddly!

John

PS Ah! great minds and all that.      It is best to use a wrenc  h that  covers the wanted torque, rather that being at one end of the range.     You might consider a 'torsion bar' wrench, like this:   Use of Torque Wrenches » Technology Transfer Services

 

They do not go out of calibration!

John

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