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Author Topic: Head nuts leaking  (Read 3929 times)

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Offline martinfan30

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Head nuts leaking
« on: July 06, 2009, 09:57:58 AM »
Why is this occurring? I used a flat piece of marble and 400 wet paper to lap the head and cylinder. Used cometic gaskets from stewart too.
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Offline BDI

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Re: Head nuts leaking
« Reply #1 on: July 06, 2009, 11:01:50 AM »
What's leaking from the head nuts  :?  Water/coolant  :? You should have used valve lapping compound and glass on top of your marble. Using Sand paper for laping brings bad bad juju :x it will always cause more problems then it fixes. The sand paper will cause the edges of what ever you are lapping to role up and the more you do it the worse it gets. Valve lapping compund Daniel son. :wink:
« Last Edit: July 06, 2009, 11:04:54 AM by BDI »
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Offline Jopiz

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Re: Head nuts leaking
« Reply #2 on: July 06, 2009, 11:47:53 AM »
Why shouldn't sand paper be used when lapping? That 400 grid is pretty coarse to me. It removes pretty much alloy.
How about lapping it on top of a glass with grid 800 up all the way to 2000 or 3000 grid? I cant see any problems with that. I have always been taught to lap in circular motions. Like number 8.    :roll:
But hey im not a machinist. That valve lapping compund will probably be better since its designed for jobs like that.

-J
« Last Edit: July 06, 2009, 11:56:24 AM by Jopiz »
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Offline BDI

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Re: Head nuts leaking
« Reply #3 on: July 07, 2009, 05:04:23 PM »
Quote from: Jopiz on July 06, 2009, 11:47:53 AM
Why shouldn't sand paper be used when lapping? That 400 grid is pretty coarse to me. It removes pretty much alloy.
How about lapping it on top of a glass with grid 800 up all the way to 2000 or 3000 grid? I cant see any problems with that. I have always been taught to lap in circular motions. Like number 8.    :roll:
But hey im not a machinist. That valve lapping compund will probably be better since its designed for jobs like that.

-J
I guess it's hard to get but I'll try one more time. As you push the part across the paper or cloth it creates a wave like a boat crossing water creates a wave. This wave even if you can't see it and even if you tape the paper down as tight as you can will take more off the edge of your part.valve laping compound smeared on to a peice of glass does not do this. It will make your part so flat that you can cut yourself on the edge. This trick was tought to me by a guy who owned a full on factory backed kawasaki race team. He told me that what he was showing me is how all the pros do it and the sand paper way is how the squids do it. One thing I can say is I have never had something leak that was done with valve laping compound. I have seen things leak done with paper and seen them get worse with more attemts to fix it using paper.
« Last Edit: July 07, 2009, 05:30:20 PM by BDI »
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Offline oic0

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Re: Head nuts leaking
« Reply #4 on: July 08, 2009, 01:47:39 AM »
What about paying someone to run it through a mill or lathe?
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Offline KXcam22

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Re: Head nuts leaking
« Reply #5 on: July 08, 2009, 12:25:56 PM »
I have used paper on glass with good results - but it is not he optimim way.  You can't take too much off and you must fiinsh be lapping the two surfaces to each other. BDI is right though and you have to be careful.  I like the compund on glass idea!!  It sounds like you are missing is the final step of lapping the head to the cylinder. Cam.
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Offline Jopiz

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Re: Head nuts leaking
« Reply #6 on: July 08, 2009, 12:47:41 PM »
So basically this method which uses valve lapping compound  brings the operation to the 21st century from the past    decades? And this can be used to lap everything from cylinder heads to anything else which require optinum fit?
Would machining give more precise surfaces or just waste of time and money?
Sorry for stupid questions  8-)

-J
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Offline barryadam

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Re: Head nuts leaking
« Reply #7 on: July 09, 2009, 05:03:17 AM »
Abrasive sheets should be attached to the surface plate using adhesive like 3M Super 77, not tape.
Unless you are using optical quality glass, the surface flatness is not as good as you think.  Plus glass will bend/flex if not supported by a flat surface.  A calibrated surface plate is preferred, but even lower grade plates can be pretty good.  And they are usually pretty cheap for a small one, like 18" x 24" size.
Grinding compound will work both ways - on the aluminum and the grinding plate and the removal will be proportional to the material hardness.  Best to use grinding compound for that final step - lapping part to part. 

<<Would machining give more precise surfaces or just waste of time and money?>>

Machining (cutting) is for getting the surfaces to the right dimension and location (parallel, perpendicular, etc.)
Machining (grinding) is for getting a better surface finish on the machined surface.
Hand surfacing is to get a completely flat surface and to get a finer surface finish (remove all cutting marks).
Hand lapping is to match two surfaces regardless of their shape/finish.

Material removal for the above is greatest to least in the order shown.
« Last Edit: July 09, 2009, 05:09:35 AM by barryadam »
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Offline BDI

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Re: Head nuts leaking
« Reply #8 on: July 09, 2009, 04:07:51 PM »
The glass is expenable, it has to be used on a peice of granit to keep it from flexing. In the words of my uncle, "do it how you see fit" . See ya at the hill.
« Last Edit: July 10, 2009, 08:26:01 PM by BDI »
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Offline cbxracer30

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Re: Head nuts leaking
« Reply #9 on: July 11, 2009, 01:56:54 PM »
I dont think your marble had a level enough surface. Maybe you should try a little yamabond on both sides of the gasket. Yamabond works wonders, it should be in everyones tool box.CBX
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Offline Jopiz

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Re: Head nuts leaking
« Reply #10 on: July 15, 2009, 08:13:41 AM »
How much compound should i put to the glass when im surfacing the part? Minor amounts or lots of? Whats generally the best way to clean the part from the compound?   :|

-J
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Offline BDI

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Re: Head nuts leaking
« Reply #11 on: July 15, 2009, 11:38:59 AM »
A thin layer is all you need you can spread it with a putty knife.
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