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aigel aigel is offline
Now in 993 land ...
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Join Date: Mar 2003
Location: L.A.-> SF Bay Area
Posts: 13,545
Originally posted by H.G.P.

The rust of course looks nothing like the above. It is speckled. sporadically speckled on the inside wall. It is not in the ring step area. I can close my eyes and move my fingers through the cylinder, and over these spots the metal is still smooth. The "pitting" I've never seen in a defective cylinder so I can't ID it. What appears as pitting I can still run my finger over and is smooth.

Well, if you can see it, it is there. To catch it with your finger nail or feel it with yor finger tip, it would have to have a rather aprupt topography, e.g. like the edge the top ring creates in a worn cylinder. Who knows, you may be fine after honing, I don't know. And it also depends much on what lifetime you expect to get from your rebuild. A 40-50k mile goal can be achieved with things that aren't perfect. If you want 100k+ miles, I'd be more careful.

I have never honed 911 cylinders, only American iron. On a water cooled engine, I'd just go get it overbored at a machine shop, if there would be any rust on the cylinder sidewall ...

Originally posted by H.G.P.

Also, the grape hone to me literally is "fine haired" hatch.. Is this what a grape hone hatch should look like?

I remember seeing very nice images of hone marks in some old haynes manuals, it may be worth flipping through them at the auto parts store. I remember even the angle being indicated at 30-40 degrees. Also, search the web for images, since any cylinder with a piston in it should look the same!

Here are some pictures of a couple of engines I was working on in the past. I still had these pics on the computer. While they aren't air cooled cylinders, they may help in trying to illustrate the size and orientation of the hone marks. These are crops out of larger images, so their resolution isn't quite up to what I'd have if I would have taken them solely to document the hone marks ...

This here is a cheap short block engine from an engine remanufacturing place. This is what the "pros" finish looks like. Including the dirt! I cleaned this one very well before it went together, trust me. Bore is just over 4" diameter.

This here is an engine that I re-ringed. It was a case of neglect (never changed engine oil and gummed up the valve guides to the point where the valve stems ran dry), so it wasn't worn beyond specs and could be brought back with a hone. Bore is just over 3.7".

This is the same engine just when I started honing. You can see the honed cylinder to the right and the unhoned one to the left. I use a ball hone but forgot the spec on the grit.

Hope this helps! If you are local to the bay area, I'd be happy to come by and take a look and I could also lend you the hone I have.

Cheers, George
97 993
81 SC (sold)
Old 01-08-2005, 01:07 AM
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