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Is this bore scoring acceptable for a rebuild? (pictures of a new block added)

4130 Views 10 Replies 4 Participants Last post by  mike1967
I took the head out on my N14 and bad news, a burnt piston and the block is very badly damaged.

Came across a used block , below are the pictures.

Cylinder 3 and 4 seem to be the worst ones, but seller says they look bad on pictures than they actually are.




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I’d not use it.
Thanks, will give this a miss.
would hone it see what you get after ie put new piston ring in bore and measure the gap where the two ends meet nearly anything under 0,20mm is ok, cant tell from pics that well and also need to hone it anyway to see what you have got,
Cheers Mike, seller wants £200 for it.

He said it's below mark which is the deepest of all marks, do you recon worth a visit and feel it out?

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i have rebuilt loads of these engines and the hone tool will remove some fairly big marks on the bores i also fit 3 piece oil rings on pistons, one of those
Thanks, Does that mean I'd have to go oversized pistons after using the hone tool due to the amount of material getting removed?
I might of quoted what you just said wrong. No. unfortunately you would have have that bored .20 over with oversized pistons.
First of all it looks like it only had about 60 thousand on it from the lack of soot on top of the pistons. Makes me wonder if someone did a head gasket on that previously.
You just have to hone it and find out what you have after you do the work. A lot of people use the bead ball type hone. I just the sanding stone one. I was apprehensive to let people know I used the other one. considering the bead ball hone is the heavily favored and stand less of a chance of damaging things.
But over the last half year or so it was not a bad investment at all. It is hard to used on the cooper engine if you are doing it without removing the oil jets for the pistons. Up and down on that little engine is about like 2 inches up 2 inches down. When you get to the work in real time. NOT THAT BAD! but close.
either way count to 30 one for each stroke of the bead ball or sanding stone tool after that you will have honed the block.
Wow something is weird with that block it has a lot going on up by the ridge. I would get a second opinion on that also.
But really it looks good to go. ridge reaming may not be a option anyway. unless someone else tried to rebuild it.
I would hone it and see if it is within .20 then continue the rebuild. I think it's good to go after a hone. pistons had the Teflon,or Kevlar on the skirts to begin with; and it just seems unlikely what ever has happened messed the bore up.
With the N14 block it is in 2 pieces anyway. So transport to the machine shop would be easy really and just take the head on up to them anyway. In fact my machine shop told me don't worry about disassembly they would do that and not charge anything extra for it. So I just left the camshafts in the head and gave it over to them.
Along with the new valves guides,valves,seals,lifters,and springs they rebuilt the head and did a dang good job at it.
Not that big of a deal where your at.
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Ok found another block, what do you guys recon about this one? pictures seems seller gave it a hand sanding and he said he gave a light wipe with 500 grit , I'm concerned why he had to do that in first place , to cover up something or not.



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What I've been taught is never touch a cylinder bore with sandpaper. The fact that he had to do that is concerning.
What I've been taught is never touch a cylinder bore with sandpaper. The fact that he had to do that is concerning.
deffo never sand paper but that said a hone tool will take out most damage within 0.24mm max and from experience ,
link below hone tool
use a fast drill and plenty of wd40 type oil the last part of the hone is done very slow and pull the hone tool in and out as to get 45 degree patterns in the bore walls ,, the intense part of hone can be done fast speed and in and out evenly after clean it all out as will residue in there,,, and see if can still see the old damage,, i also at this point put one of the piston rings about a inch down and put feeler gauge in the gap where both ends meet,, under 0.20mm is ok on these engines,, new is around 0.05mm ,, i have done loads of them with over 100k on them and all end up good again
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