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Join Date: Feb 2007
Location: Taipei, Taiwan
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Pits on cylinder top, reusable?
Hi everyone,
Just got a used p/c set for my engine rebuild but one cylinder has three pits on the top rim as shown in the picture. The piston would not reach so high but since the nickle plating looks cracking at the pits, will there be any adverse effect developing in the future if it's used for rebuild? Any comments appreciated, thanks!   
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07-08-2009, 06:13 AM
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Location: Cape Vincent, NY
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I would have some big concerns about that cylinder.
1. The effect on sealing between cylinder and head. 2. The potential for further damage from metal fatigue at the damaged areas. 3. Chunks breaking off and getting into the engine. Personally, I would get another cylinder to replace that one. Just too much potential for damage. If you can find another of same height it would probably be less than the machine work to have this fixed and get all the cylinders to the same height as it appears that a significant amount of resurfacing is going to be needed; and then you do not have to worry about future cracking of the surface. As I have never used cylinders that were like that on any engine, nor know anyone, I can only state why I don't use them, out of fear of failure.
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1968 911S "Leona" Air goes in and out, blood goes round and round, any variation on this is a bad thing. |
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07-08-2009, 07:04 AM
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3 restos WIP = psycho
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Considering the rings never go that high, welding a blob of AL on there and carefully filing the blob should be enough. That's just a hack opinion, though.
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07-08-2009, 07:25 AM
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Thanks! The pits all protrude internally instead of upwards so the sealing surface is pretty flat except for some depression on the inner edge. Maybe I can file those irregularity off to prevent poosible tiny chunks breaking off and falling into the chamber.
The original cylinders of my engine are of the same Ht group (5) as the replacement set and some look pretty nice except that the criss-cross hone patterns are not as distinct as the replacement set. My wrench said they are fine but I am not so sure.
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07-08-2009, 04:49 PM
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junk.
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https://www.instagram.com/johnwalker8704 8009 103rd pl ne Marysville Wa 98270 206 637 4071 |
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07-09-2009, 04:24 AM
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Listen to John.
Alex
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Its easier asking dumb questions than fixing dumb mistakes 1974 Porsche 911 Coupe, RSR Project 1976 Porsche 911 Targa, Black 1986 Porsche 911 Carrera, Black 2006 Porsche Cayenne S, Black |
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07-09-2009, 12:47 PM
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I'd go with John... but you could make some nice wall art with the leftovers, so its not a total loss
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Don't Lift... Don't Lift... Don't Lift  '75 Targa in "Arrest Me" Red, 3.0SC ('79) engine, Bilsteins, Turbo Tie-rods, SSIs into 2-1 M&K muffler... and looking for my next upgrade. |
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07-09-2009, 01:57 PM
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Got it, thanks!
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07-09-2009, 02:37 PM
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