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914World.com _ 914World Garage _ rebuild again
Posted by: worn Dec 27 2015, 07:03 PM
Saw a thread on the Pelican site showing a set of delaminated Nikasil cylinders. After cleaning up mine I see a few pinpricks. Cylinder 5 is by far the worst offender with what looks not so good to me. Would value response from those who know. I recognize that no 914 came equipped with them.
Longer view
Closer up
Would you be worried? Reusable?
Thanks!!
Posted by: mb911 Dec 27 2015, 08:47 PM
I would use or send to us chrome in fondulac and have them redo them..
Posted by: Jake Raby Dec 27 2015, 09:43 PM
Ring tensions were ran too high for Nikisil in these pics. 8-11# is perfect for Nikiail, but you'll usually need to fish scale them to get them there, or work on the oil ring expanders to drop them.
Posted by: Mark Henry Dec 28 2015, 08:39 AM
Simple test feel the top ring ridge, if you feel a rolling ridge (opposed to a used steel cylinder's harder, sharper ring ridge) then you should have it replated. If unsure you should have it checked with a bore gauge.
Very high milage cylinders will begin to fishmouth, meaning the top of the bore will be bigger than the bottom.
A few small pits in nikasil is normal and OK.
Delamination looks sort of like chrome has flaked off a bumper and needs replating.
Posted by: worn Dec 28 2015, 10:12 AM
Simple test feel the top ring ridge, if you feel a rolling ridge (opposed to a used steel cylinder's harder, sharper ring ridge) then you should have it replated. If unsure you should have it checked with a bore gauge.
Very high milage cylinders will begin to fishmouth, meaning the top of the bore will be bigger than the bottom.
A few small pits in nikasil is normal and OK.
Delamination looks sort of like chrome has flaked off a bumper and needs replating.
Thanks Mark. Initial measurements were very encouraging but I haven't run the mic that way. When I washed them there was no perceptible ridge.
Posted by: worn Dec 28 2015, 10:13 AM
Ring tensions were ran too high for Nikisil in these pics. 8-11# is perfect for Nikiail, but you'll usually need to fish scale them to get them there, or work on the oil ring expanders to drop them.
As in 8 to 11 pounds of tension needed to...pull the piston up or down with rings installed? Thanks Jake. Learning slowly but steadily.
Posted by: Luke M Dec 28 2015, 10:20 AM
I just had my brothers 3.0 cylinders redone in Nikasil. Waited 5 weeks for them to come back to only find one cylinder had a deep pit in it. I'm still waiting for a call back but I know with the Holidays most places shut down until the new year.
If you do send them out take good pics of the cylinders and note any issues on them.
The cylinders where real smooth when I sent them in so my issue is with the process/final inspection at the shops end. I got the same cylinders back that I sent in but some places do a swap for your cores.
Posted by: Mueller Dec 28 2015, 10:25 AM
Ring tensions were ran too high for Nikisil in these pics. 8-11# is perfect for Nikiail, but you'll usually need to fish scale them to get them there, or work on the oil ring expanders to drop them.
As in 8 to 11 pounds of tension needed to...pull the piston up or down with rings installed? Thanks Jake. Learning slowly but steadily.
I'm guessing lubed with oil as well?
Posted by: sixnotfour Dec 28 2015, 10:46 AM
Use Goetze piston rings ,you will have no problems....
when you took off the old rings was the oil ring one piece or 3 piece ??
if one piece those are just well used , no ring problem...
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