Ghibli II winter works

spacecadet

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333
As expected the leak if coming somewhere from the gasket, but can't tell if it's from above or below


Heads will come down, will remove them both this time, as so far I've only removed one side. Will double check stud witness marks, and also try to find a place who will measure surface roughness. Also measure the thickness, but not sure if I can properly measure it because the heads are slightly angled.
 

spacecadet

Member
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333
The story is not over.

Finally I was able to source a pair of used cylinder heads. Couldn't find 2.0L heads, but I was told the 2.8L heads are also usable. 2.0L and 2.8L heads have different part numbers, but the heads listed for the Ghibli Cup, which is 2.0L, are also using the same part numbers as the 2.8L heads for earlier Ghiblis and QP4s. After comparing the different heads, I also couldn't find any difference. If there is, that has to be in the coolant ports, but the casting number also match: COSCAST XXX 1173 2AD, where XXX seems to be some kind of serial number or variant.

Took apart the new set to clean (lots of sludge) and verify everything. Found 2 bent intake valves, right at the valve head, they slightly don't close, no damage to the guides. The bigger problem is that one exhaust cam journal is very badly marked. The cap is not so bad, and the cam also looks ok.

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Todays took to a machine shop (a different one), but only for pressure testing at this point, told them not to touch them in any other way. As I see the only possible repair is welding up with TIG and line boring, sleeving is not possible because of the thin wall, close thread.

Regarding the leak: at this point I'm pretty sure it's the surface roughness. After disassembly the pattern is visible on the custom gaskets, which have a metal layer on the side facing the head.
 
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dt95aac

Junior Member
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42
My understanding is that 2.8 and 2.0 heads are interchangeable.

The 2.8 flow a bit better (bigger valves maybe?) hence they were used in the Cup cars.

Great to see some progress, please keep going.
 

azapa

Member
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943
Regarding the leak: at this point I'm pretty sure it's the surface roughness. After disassembly the pattern is visible on the custom gaskets, which have a metal layer on the side facing the head.
The roughness should be an easy fix. Even a nice big, new and flat oilstone worked back and forth manually should solve that. Good luck anyway, you have admirable courage and drive for your project!
 

spacecadet

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333
Thanks for the encouragements!

The 2.8 flow a bit better (bigger valves maybe?) hence they were used in the Cup cars.
I heard the same initially, but both have 30mm intake, and 27.5mm exhaust valves.

The roughness should be an easy fix. Even a nice big, new and flat oilstone worked back and forth manually should solve that.
That's my plan, using a big, known flat metal block and emery cloth.

Pressure testing revealed no problems, the journal is currently under repair. From the two sets I'll be able to build a proper pair.
 

azapa

Member
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943
That's my plan, using a big, known flat metal block and emery cloth.

Pressure testing revealed no problems, the journal is currently under repair. From the two sets I'll be able to build a proper pair.
I have done that before, but the results are not that good as the emery cloth creases up and the corners round off a little. I guess you should practice first with different techniques on an old casting.
 

spacecadet

Member
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333
Cam bearing after repair. I'll do a very light polishing on these, because they couldn't make it more smooth with the line boring machine.

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