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Under the radar
Join Date: May 2007
Location: Fortuna, CA. On the Lost Coast near the Emerald Triangle
Posts: 7,129
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Wonky cylinders
We got our cylinders back from EBS. 2,7 bored to 92mm. Bores look good.
However when I measured the cylinder heights some of the cylinders were not perfectly square. One cylinder in particular measured 3.354" on one side and 3.360" on the other. So the question is will this work, or do I need to send them out? Or clean them up on a glass plate with 400 grit?  Two other cylinders were also not square, but not as bad as that one. What say the brain trust?   
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Gordon ___________________________________ '71 911 Coupe 3,0L outlawed #56 PCA Redwood Region, GGR, NASA, Speed SF Trackrash's Garage :: My Garage |
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05-11-2022, 07:11 PM
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Registered
Join Date: Jul 2021
Posts: 689
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I don't know the answer but I do know what questions you need to answer before others can answer.
A. Will the angle tilt the cylinder relative to the case, or just the cylinder head relative to the cylinder? In other words, which end(s) are/is not orthogonal to the barrel? and B. Which direction does the angle go? Parallel to the crank, or orthogonal to it? Orthogonal will simply rotate the piston on its pin, while parallel will attempt to bend the piston, pin and con rod system. Sent from my SM-G988B using Tapatalk |
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05-11-2022, 07:38 PM
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Registered
Join Date: Jul 2013
Location: Brisbane, Australia.
Posts: 2,609
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Did you measure them before they went out?
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Always learning. www.aircooledporsches.com.au See me bumble my way through my first EFI and TURBO conversion! https://youtu.be/bpPWLH1hhgo?si=GufVhpk_80N4K4RP |
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05-12-2022, 01:48 AM
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Registered
Join Date: Dec 2007
Location: Just a little north of 13669/Nation's capital
Posts: 1,289
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They need to be square and equal too. If not, proper sealing will be unlikely and in addition, the cam box might be distorted affecting the ability of the cam to turn without difficulty.
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1986 Targa Guards Red 2021 MT09 SP |
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05-12-2022, 04:10 AM
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It's a 914 ...
Join Date: Jan 2008
Location: Ossining, NY
Posts: 4,706
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.006" sounds like a lot. Something isn't going to seal properly, either at the cylinder head interface (bad), or at the base of the cylinder where it meets the case (not quite as bad possibly, but still bad). Not sure truing them up on a glass surface is going to bring this kind of unevenness back into spec.
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05-12-2022, 04:18 AM
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Try not, Do or Do not
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A machinist with a good lathe can square them up. Base gaskets to achieve the proper deck are readily available.
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Henry Schmidt SUPERTEC PERFORMANCE Ph: 760-728-3062 Email: supertec1@earthlink.net |
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05-12-2022, 05:29 AM
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Under the radar
Join Date: May 2007
Location: Fortuna, CA. On the Lost Coast near the Emerald Triangle
Posts: 7,129
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Quote:
I didn't bother to measure them before sending them out, since there was not real leakage at the base, the head seals were pristine, and the bores looked good. Live and learn I guess. But I also assumed that EBS would checked them. Oh well. We will get it done right.
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Gordon ___________________________________ '71 911 Coupe 3,0L outlawed #56 PCA Redwood Region, GGR, NASA, Speed SF Trackrash's Garage :: My Garage |
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05-12-2022, 09:50 AM
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Registered
Join Date: Nov 2019
Location: Kansas City
Posts: 585
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Nice catch. I like the idea of using a mike there. I use a height gauge and have noticed some uneven measurements before but not as much as .006”. Wonder if that cylinder has always been that way.
Will the machinist just cut on the bottom ? or top of the cylinder…ce ring groove.. or both ? Just curious where the .006 deviation is top or bottom. Daniel
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it's not leaking....it's just marking it's territory |
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05-12-2022, 05:29 PM
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My Garage
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