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Rb25 rebuild new piston scratched cylinder

Prof_Finesser
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Prof_Finesser Enthusiast

Prof_Finesser

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Hello I have started my rebuild of my rb25 it has been hone and bored to 87mm cp piston and manley rods.  I gapped all the rings and installed the pistons I made sure to deburr all the rings too.  I rotated the assembly and looked fine and then today I was putting on the oil pump and noticed that there is some light scratches on the cylinder walls.  I can't feel then at all I'm not sure if there wasn't enough oil in the bores or if I rotated the assembly too much but tomorrow I'm going to remove all the pistons and make sure the rings are all deburred please lmk what you guys think anything helps.

Duncan Grand Master

Duncan

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Doesn't sound like good news, if you can feel it with a finger nail it almost certainly needs a hone and possibly even a bore out.

Sucks, but not worth having an issue. I once had to get a block re-bored when I caught a ring installing it and scratched the bore. Might also be your ring end gaps were too tight

Prof_Finesser Enthusiast

Prof_Finesser

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6 hours ago, Duncan said:

Doesn't sound like good news, if you can feel it with a finger nail it almost certainly needs a hone and possibly even a bore out.

Sucks, but not worth having an issue. I once had to get a block re-bored when I caught a ring installing it and scratched the bore. Might also be your ring end gaps were too tight

I took out the pistons today and found that all of them have some type of vertical scratch on the skirts I'm going to talk to my machinist today and see what there is to do.  Hoping for the best this is my first rebuild.

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Prof_Finesser Enthusiast

Prof_Finesser

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10 hours ago, Murray_Calavera said:

If your concerned, why not take the block back to the machinist that originally did the bore/hone? They would be able to advise if the hone needs to be redone.  

I talked to my machinist he said to take a emery cloth and wipe out the scratches and it should be fine he said since the scratches don't catch my nail its fine

Prof_Finesser Enthusiast

Prof_Finesser

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3 hours ago, Duncan said:

Good to hear. Did they have a theory why the scratches occurred? Are you certain the ring gaps are OK (check them before reinstalling pistons!)

I wiped the scratches and they went away it was only about 1-3 wipes from very fine emery cloth he said it could have been from not enough oil in the bores or too much rotating of the assembly also he said that the type of ring compressor I'm using can make the rings catch a bit.  Before I put the pistons back together I will check the gaps and double check the rings for deburring.

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