 Rough cylinder walls, What can be the cause? |
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| HansJan |
 Oct 19 2016, 09:28 PM
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#1
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Member  Group: Members Posts: 395 Joined: 5-April 16 From: Sugar Land TX Member No.: 19,860 Region Association: Southwest Region 
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Hello,
Today the shop had taken the engine out of the car, just to replace the very stiff valve springs. When the heads came off we noticed that there are rough areas on the cylinder walls. Not everywhere, but at least two areas per cylinder. FYI: Cylinders are 103.8 mm (by AA). Pistons are also by AA. Markings on cam: CWC Valves Intake: 44.35 mm Valve Exhaust: 38 mm My question to the brain-trust is: What could be the cause for the rough areas? Some back ground info: This car supposed to have "Nickies" Cylinders and JE-Pistons. Obviously the (Craigslist) seller and I are no friends. After receiving it, I drove the car for less then 10 minutes before the car caught on fire.  |
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| McMark |
Oct 20 2016, 12:59 PM
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#2
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914 Freak! Group: Retired Admin Posts: 20,179 Joined: 13-March 03 From: Grand Rapids, MI Member No.: 419 Region Association: None |
I can see from the cylinder fins that those marks are on the top or bottom. I'm guessing the top since the bottom usually has oil leaking out of it.
My WAG (wild ass guess) is that it's something to do with the rings chattering or piston rock. 104 pistons aren't really reliable. Did you measure the stroke? An engine that uses 104s has to have a lot of other engine components upgraded to do right. If the rest of the components aren't right things like piston speed and rod ratio can cause problems. Building a 104 engine right will cost as much or more than buying a 911 engine, but won't be nearly as reliable or powerful. Check over the rest of the components, but if I were you I would plan on installing new 96mm pistons and cylinders. |
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| porschetub |
Oct 21 2016, 01:37 AM
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#3
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Advanced Member Group: Members Posts: 4,699 Joined: 25-July 15 From: New Zealand Member No.: 18,995 Region Association: None |
QUOTE(McMark @ Oct 21 2016, 07:59 AM)  I can see from the cylinder fins that those marks are on the top or bottom. I'm guessing the top since the bottom usually has oil leaking out of it. My WAG (wild ass guess) is that it's something to do with the rings chattering or piston rock. 104 pistons aren't really reliable. Did you measure the stroke? An engine that uses 104s has to have a lot of other engine components upgraded to do right. If the rest of the components aren't right things like piston speed and rod ratio can cause problems. Building a 104 engine right will cost as much or more than buying a 911 engine, but won't be nearly as reliable or powerful. Check over the rest of the components, but if I were you I would plan on installing new 96mm pistons and cylinders. (IMG:style_emoticons/default/agree.gif) huge cylinders that go out of round when hot and out of shape,the heads get less supportive @ register size,see the hone marks still there but think not much is staying round ,AA pistons ????? some don't get good press. I tend to remember the thin T1 no bore kits from a long way back,same issue for another reason,just saying ??? |
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| HansJan |
Oct 21 2016, 06:29 AM
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#4
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Member Group: Members Posts: 395 Joined: 5-April 16 From: Sugar Land TX Member No.: 19,860 Region Association: Southwest Region
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QUOTE (IMG:style_emoticons/default/agree.gif) huge cylinders that go out of round when hot and out of shape,the heads get less supportive @ register size,see the hone marks still there but think not much is staying round ,AA pistons ????? some don't get good press. I tend to remember the thin T1 no bore kits from a long way back,same issue for another reason,just saying ??? Thanks for your input. What is is T1? |
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| 76-914 |
Oct 21 2016, 07:35 AM
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#5
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Repeat Offender & Resident Subaru Antagonist Group: Members Posts: 13,502 Joined: 23-January 09 From: Temecula, CA Member No.: 9,964 Region Association: Southern California
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QUOTE(Hans Jan @ Oct 21 2016, 05:29 AM) QUOTE (IMG:style_emoticons/default/agree.gif) huge cylinders that go out of round when hot and out of shape,the heads get less supportive @ register size,see the hone marks still there but think not much is staying round ,AA pistons ????? some don't get good press. I tend to remember the thin T1 no bore kits from a long way back,same issue for another reason,just saying ??? Thanks for your input. What is is T1? Type 1 = VW and some bus |
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Posts in this topic
Hans Jan Rough cylinder walls Oct 19 2016, 09:28 PM
wndsrfr
Hello,
Today the shop had taken the engine out o... Oct 20 2016, 05:31 AM N_Jay Are the marks on the front and back or top and bot... Oct 20 2016, 07:44 AM injunmort looks like some one forgot the wrist pin keepers. ... Oct 20 2016, 12:43 PM
worn
I can see from the cylinder fins that those marks... Oct 20 2016, 01:12 PM injunmort piston speed changes dramatically at tdc and btdc.... Oct 20 2016, 04:16 PM
worn
piston speed changes dramatically at tdc and btdc... Oct 21 2016, 08:16 AM McMark Yeah, I wrote that poorly. What I had in mind is ... Oct 21 2016, 08:42 AM injunmort my apologies worn, i misunderstood the question. i... Oct 21 2016, 11:59 AM Hans Jan
my apologies worn, i misunderstood the question. ... Oct 22 2016, 10:46 AM cwpeden
my apologies worn, i misunderstood the question.... Oct 22 2016, 11:18 AM cwpeden From a machinists point of view, those look like r... Oct 22 2016, 11:16 AM |
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