Borescope reveals tell-tale half moon paterns from exhaust valves... - Page 4 - Dorkiphus.net
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  #31  
Old 10-02-2007, 09:34 AM
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Quote:
Originally Posted by SkipC View Post
Anyone,
Are there any symptoms of over-rev damage to the rods, bolts, and/or bearings ? Or, does the car run and sound fine until the rod lets go ?
Bent valves usually are the telltail issues. Rest are discovered at tear down or down the road following a catastrophic failure (not meant as a comment other than in response to a specific question).
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  #32  
Old 10-05-2007, 10:34 PM
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Originally Posted by Eli View Post
Here's a clip of what my 964 sounded like after a similar experience at the track. Broken rocker arms, bent valves, etc...Ended up rebuilding both top and bottom.

SOUNDCLIP

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Good luck, hope it's something minor.
Holy Crap Batman ... you didn't tell me about that
BTW, that engine now purrs like a kitty!

Jass, found the cause of the rough idle, the rubber intake boot cracked at the point where air enters the idle speed control valve. Eli gave me a spare with the engine and took about 1/2 hr to swop.
Not only idles better, but huge improvement on the top end. It must have been running lean.

Eli, next time your up you gotta drive this thing. It'll make you smile!

On my 3.0 I had slight piston, valve moons and it ultimately caused a broken ring and bad leakdown on #2. On the rebuild I found the problem with a previous rebuild and corrected it. The valve seats were not ground much after they were installed. Thus the valves protruded into cylinder a hair more than normal. These were fixed at the machine shop that replaced the guides.
Put in all new valves and rockers while I was at it to eliminate any concerns.

The clearances were slightly tight after I finished, But that was solved by timing the cams to euro specs. A little retarded. This provided more than the minimum clearance recommended and that engine was very strong when finished.
I hope this works out for you!
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