I really do need my head looking at..

my cylinder head that is.

After making a second copper head gasket to get the correct cam chain tension and fitting the head, I found I could see light through the joint! Worse still, it was at the edge near where the oil gallery runs. So back off with the head and this is what I found.

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Ideally the head and barrel should be skimmed on a horizontal milling machine to correct the “out of flat” but I don’t have one. So it’s back to my friends trusty old Colchester lathe to see if I can skim the head and barrel on that.

First problem was how to hold the head and I settled on making a frame from aluminium extrusion that I secured to the head using the 4 x M6 cam cover holes. I then clamped the aluminium frame in a 4 jaw chuck and trued up the head face using a dial indicator.

Using a new TCT tip tool, I skimmed the head, using a very slow cross slide auto feed, to get the smoothest finish possible and in total I removed 0.19mm.

To skim the barrel, I first made a plug out of nylon, that was a tight slide fit into the bore – tight enough that it needed tapping in place with a mallet but hopefully not so tight that it would split the steel liner.  The plug served 2 purposes. Firstly to allow the liner skirt to be clamped in a 3 jaw chuck without risk of crushing the skirt and secondly to keep the barrel true by supporting it with a floating tailstock.

To true the face, I removed 0.14mm. The good news was that removing a total of 0.33mm, enabled me to use the fist copper gasket I made; the 1,2mm thick one.

Now the joint is perfect and clamps up without daylight!

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Job done (hopefully).

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