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Well, it looks like of the 12 exhaust valves I have, Nos. 1, 7, 9 and 12 are usable, and the rest are too worn. The orange triangle is actually the length measurement with an amount deducted to get the overall length on the same scale as the diameter. #1 is just fine; 7 has a short stem, but this should not affect geometry because the adjuster can take it up; 9 has a slightly undersize diameter at the midpoint, but I'll measure it again to verify; and 12 looks good.

So it looks like two new intake valves at $135 a pop are in order. I suppose I could scrounge some better used ones, but given that the youngest 2,0 valves are 38 years old, the odds of finding good ones isn't that great, and this engine will hopefully not be rebuilt for decades.
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Ex-'71 911 PCA C-Stock Club Racer #806 (Sold 5/15/13)
Ex-'88 Carrera (Sold 3/29/02)
Ex-'91 Carrera 2 Cabriolet (Sold 8/20/04)
Old 04-13-2007, 09:08 AM
  Pelican Parts Technical Article Directory    Reply With Quote #41 (permalink)
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PBH; I don't have a micrometer that goes to 111.75mm +/- .05mm, mine max out at 100mm. So the setup was done using FOUR gage blocks, as I couldn't do it with fewer using my 81 set. You can see the pile on the surface plate next to the comparator stand. I was using the plate for something else. The blocks were:

100mm
7.5mm
3.0mm
1.25mm
-------
111.75mm

Then the indicator was zeroed and the valve placed under it and the reading noted. Of course the readings are all over the map; any carbon still on the face, even in a barely-visible amount, throws the reading off, but the tips will probably be ground as part of the valve job.
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'66 911 #304065 Irischgruen
Ex-'71 911 PCA C-Stock Club Racer #806 (Sold 5/15/13)
Ex-'88 Carrera (Sold 3/29/02)
Ex-'91 Carrera 2 Cabriolet (Sold 8/20/04)
Old 04-13-2007, 09:22 AM
  Pelican Parts Technical Article Directory    Reply With Quote #42 (permalink)
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This was a somewhat shakey setup to measure the cylinder head. I sent these heads out to be rebuilt, and I want to know exactly how much material I have to take off the chain box covers, if any, in order to center the cams.



The trouble here is that I don't own a test indicator. You can't use a height gauge properly without some sort of indicator on the end, because you don't know whether you are tilting the indicator or bending the measuring arm. So you attach a test indicator that's horizontal, zero the height gauge with the test indicator at a particular reading (something more than zero so you preload the test indicator's movement for accuracy, or if it has a moveable dial, preload it and dial it back to zero) and then read your height measurement with the test indicator at the very same reading.

I said shakey setup because all my indicators have 9mm stems instead of the AGD stem. The height gauge test indicator holder has a provision to mount an AGD or a dovetail-type indicator, but not the metric one. So I had to improvise, and the way the indicator locked up wasn't perfect. But close enough for me.

All the heads were pretty close to the same measurement, once they are machined they should be identical.
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'66 911 #304065 Irischgruen
Ex-'71 911 PCA C-Stock Club Racer #806 (Sold 5/15/13)
Ex-'88 Carrera (Sold 3/29/02)
Ex-'91 Carrera 2 Cabriolet (Sold 8/20/04)

Last edited by 304065; 05-10-2007 at 07:24 AM..
Old 05-10-2007, 07:20 AM
  Pelican Parts Technical Article Directory    Reply With Quote #43 (permalink)
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Could you make a shim the same profile as the sealing surface between the cam tower and head? If the head was machined .010 then use .010 shim material and then everything stays the same, cam boxes, cooling tin etc? or would it be best to add it back in to the cylinder base?
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Last edited by cgarr; 05-10-2007 at 07:35 AM..
Old 05-10-2007, 07:30 AM
  Pelican Parts Technical Article Directory    Reply With Quote #44 (permalink)
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I would be hesitant to introduce a metal shim there due to the possibility of oil leaks. A thicker gasket, perhaps, even a piece of rubber cut to the exact shape that would conform to the sealing surface on the case and the chain box.

Anchor Atlantic, who I am using to rebuild my heads, cuts every head they rebuild to renew the sealing surface, but is careful to only remove the minimum necessary, sometimes as little as .001-002" (.025-.050mm). An amount like this is probably within the tolerance of the hole in the chain box for the cam, and the difference in engine width would be picked up by the chain tensioner.

But you can't tell unless you measure the before and after, particularly because the chain box may have been surfaced or lapped before.
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'66 911 #304065 Irischgruen
Ex-'71 911 PCA C-Stock Club Racer #806 (Sold 5/15/13)
Ex-'88 Carrera (Sold 3/29/02)
Ex-'91 Carrera 2 Cabriolet (Sold 8/20/04)
Old 05-10-2007, 08:08 AM
  Pelican Parts Technical Article Directory    Reply With Quote #45 (permalink)
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